Science.gov

Sample records for permeation ustanovka dlya

  1. Hydrogen Permeation Barrier Coatings

    SciTech Connect

    Henager, Charles H.

    2008-01-01

    Gaseous hydrogen, H2, has many physical properties that allow it to move rapidly into and through materials, which causes problems in keeping hydrogen from materials that are sensitive to hydrogen-induced degradation. Hydrogen molecules are the smallest diatomic molecules, with a molecular radius of about 37 x 10-12 m and the hydrogen atom is smaller still. Since it is small and light it is easily transported within materials by diffusion processes. The process of hydrogen entering and transporting through a materials is generally known as permeation and this section reviews the development of hydrogen permeation barriers and barrier coatings for the upcoming hydrogen economy.

  2. Hydrogen permeation through metals

    SciTech Connect

    Huhn, D.K.

    1985-01-01

    The permeation of hydrogen through metals was studied both theoretically and experimentally. Gas phase permeation experiments with nickel, iron, and iron-titanium alloys were done at low temperatures, 270 to 343 K, and high temperatures, 751 to 384 K, with hydrogen pressures ranging from 10/sup 3/ to 10/sup 5/ Pa. Experiments at low temperatures used an electrochemical cell to detect the permeating hydrogen, deuterium, or hydrogen-deuterium flux. At high temperatures a vacuum system equipped with a mass spectrometer measured the permeating hydrogen flux. The permeability and diffusivity of hydrogen through nickel membranes, 10/sup -4/ to 10/sup -5/ m in thickness, was measured in the temperature range of 580 to 270 K. The experimental results did not exhibit postulated surface effects; however, trapping of hydrogen was observed with a trap density of 2.5 x 10/sup 23/ sites/m/sup 3/ and a binding energy of 33 kJ/mole. The permeability of hydrogen through iron-titanium alloys increased with titanium concentration with a maximum increase of approximately 10% for a Fe-3.04 wt% Ti alloy compared to pure iron. High temperature diffusivity measurements showed a small decrease in diffusivity with titanium concentration; therefore, the solubility increased.

  3. Glove permeation by organic solvents

    SciTech Connect

    Nelson, G.O.; Lum, B.Y.; Carlson, G.J.; Wong, C.M.; Johnson, J.S.

    1981-03-01

    The vapor penetration of 29 common laboratory solvents on 28 protective gloves has been tested and measured using gas-phase, infrared spectrophotometric techniques to determine the permeation characteristics. Five different types of permeation behavior were identified. No one glove offered complete protection against all the solvents tested. The permeation rate of the solvent was found to be inversely proportional to glove thickness for a given manufacturer's material. Of two solvent mixtures tested, one exhibited a large, positive, synergistic rate.

  4. Transungual permeation: current insights.

    PubMed

    Bhuptani, Ronak S; Deshpande, Ketaki M; Patravale, Vandana B

    2016-08-01

    Nail disorders are beyond cosmetic concern; besides discomfort in the performance of daily chores, they disturb patients psychologically and affect their quality of life. Fungal nail infection (onychomycosis) is the most prevalent nail-related disorder affecting a major population worldwide. Overcoming the impenetrable nail barrier is the toughest challenge for the development of efficacious topical ungual formulation. Sophisticated techniques such as iontophoresis and photodynamic therapy have been proven to improve transungual permeation. This article provides an updated and concise discussion regarding the conventional approach and upcoming novel approaches focused to alter the nail barrier. A comprehensive description regarding preformulation screening techniques for the identification of potential ungual enhancers is also described in this review while highlighting the current pitfalls for the development of ungual delivery. PMID:26419676

  5. Optoacoustic cell permeation

    NASA Astrophysics Data System (ADS)

    Visuri, Steven R.; Heredia, Nicholas J.

    2000-06-01

    Optically generated acoustic waves have been used to temporarily permeate biological cells. This technique may be useful for enhancing transfection of DNA into cells or enhancing the absorption of locally delivered drugs. A diode- pumped frequency-doubled Nd:YAG laser operating a kHz repetition rates was used to produce a series of acoustic pulses. An acoustic wave was formed via thermoelastic expansion by depositing laser radiation into an absorbing dye. Generated pressures were measured with a PVDF hydrophone. The acoustic waves were transmitted to culture and plated cells. The cell media contained a selection of normally-impermeable fluorescent-labeled dextran dyes. Following treatment with the opto-acoustic technique, cellular incorporation of dyes, up to 40,000 Molecular Weight, was noted. Control cells that did not receive opto-acoustic treatment had unremarkable dye incorporation. Uptake of dye was quantified via fluorescent microscopic analysis. Trypan Blue membrane exclusion assays and fluorescent labeling assays confirmed the vitality of cells following treatment. This method of enhanced drug delivery has the potential to dramatically reduce required drug dosages and associated side effects and enable revolutionary therapies.

  6. MCPA permeation through protective gloves.

    PubMed

    Purdham, J T; Menard, B J; Bozek, P R; Sass-Kortsak, A M

    2001-10-01

    Permeation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in commercial herbicide formulations through common protective glove types was evaluated to aid in the selection of appropriate skin protection. The ASTM test method F739-91 was used to measure the permeation of two undiluted formulations, one containing a salt, and the other an ester form of MCPA. The four glove types tested were natural rubber, neoprene 73, nitrile 37-145, and Viton-coated chloroprene. Triplicate tests of each combination of formulation and glove material were conducted. Permeation cells with a 0.01 M sodium hydroxide collection medium were used for the experiments. Aliquots of the collection medium were withdrawn at regular intervals and acidified, and quantification of the free acid was achieved using HPLC-UV (230 nm). There was no appreciable permeation of the salt formulation over a 24-hour test period. For the ester formulation, the following mean steady-state permeation rate (microg x cm(-2) min(-1)) and mean lag time (hours), respectively, were measured: Viton (0.06, 17.8), natural rubber (0.08, 15.4), neoprene 73 (0.21, 15.1), and nitrile (0.04, 24.2). Permeation was associated with significant swelling, averaging a nearly 30 percent increase from the pre-immersion thickness. All four glove types provide adequate protection against permeation by the salt formulation and at least eight-hour protection against the ester formulation. Given the greater permeation of the ester formulation, the salt formulation of MCPA herbicide should be used whenever possible. PMID:11599545

  7. Nitrile glove permeation of benomyl.

    PubMed

    Zainal, H; Hee, S S Que

    2006-04-01

    The aim of this study was to investigate permeation of the fungicide benomyl at its highest field application concentration (0.70 mg/mL) in Benlate 50 WP aqueous solution (1.4 mg/mL) through two types of unsupported and unlined nitrile gloves--a disposable latex glove (Safeskin) and an industrial chemical-resistant glove (Solvex)--using an American Society for Testing and Materials (ATSM)-type permeation cell with isopropanol collection medium. The permeation cell was contained in a moving-tray water bath at 30.0 degrees C +/- 0.5 degrees C. The collection medium was evaporated and the residue derivatized with an optimized method (2,3,4,5,6-pentafluoro)benzyl bromide to form the disubstituted derivative of carbendazim (CARB), CARB.2PFB. The latter in isooctane was then quantified by gas chromatography- 63Ni-electron capture detection (GC-ECD) by the internal standard method. GC-ECD, GC-mass spectrometry (GC-MS), and reflectance infrared investigations showed that little degradation of benomyl occurred in the challenge solution of aqueous Benlate during an 8-hour exposure period. Benomyl was collected as a mixture of CARB and benomyl as shown by the presence of a diagnostic chromatographic peak identified by GC-MS. The amounts permeated during the same time period were always higher for Safeskin than for Solvex gloves, with the latter being approximately 18 times more protective than the former after 8 hours of continuous exposure. Although the Solvex gloves were safe to wear at least for 4 hours and for almost 8 hours, the ASTM breakthrough threshold was used as reference and thus ignored carcinogenic effects. Reflectance infrared investigations detected benomyl and CARB on the glove challenge surface after drying and confirmed that the cleaned glove surfaces after permeation experiments did not differ in infrared reflectance spectra from the corresponding surfaces just before the permeation experiments. PMID:16446997

  8. Hydrogen-isotope permeation barrier

    DOEpatents

    Maroni, Victor A.; Van Deventer, Erven H.

    1977-01-01

    A composite including a plurality of metal layers has a Cu-Al-Fe bronze layer and at least one outer layer of a heat and corrosion resistant metal alloy. The bronze layer is ordinarily intermediate two outer layers of metal such as austenitic stainless steel, nickel alloys or alloys of the refractory metals. The composite provides a barrier to hydrogen isotopes, particularly tritium that can reduce permeation by at least about 30 fold and possibly more below permeation through equal thicknesses of the outer layer material.

  9. Gas Permeation Computations with Mathematica

    ERIC Educational Resources Information Center

    Binous, Housam

    2006-01-01

    We show a new approach, based on the utilization of Mathematica, to solve gas permeation problems using membranes. We start with the design of a membrane unit for the separation of a multicomponent mixture. The built-in Mathematica function, FindRoot, allows one to solve seven simultaneous equations instead of using the iterative approach of…

  10. Preactivated thiomers: Permeation enhancing properties

    PubMed Central

    Wang, Xueqing; Iqbal, Javed; Rahmat, Deni; Bernkop-Schnürch, Andreas

    2012-01-01

    The study was aimed to prepare a series of poly(acrylic acid)-cysteine-2-mercaptonicotinic acid conjugates (preactivated thiomers) and to evaluate the influence of molecular mass or degree of preactivation with 2-mercaptonicotinic acid (2MNA) on their permeation enhancing properties. Preactivated thiomers with different molecular mass and different degree of preactivation were synthesized and categorized on the basis of their molecular mass and degree of preactivation as PAA100-Cys-2MNA (h), PAA250-Cys-2MNA (h), PAA450-Cys-2MNA (h), PAA450-Cys-2MNA (m) and PAA450-Cys-2MNA (l). In vitro permeation studies, the permeation enhancement ability for preactivated thiomers was ranked as PAA450-Cys-2MNA (h) > PAA250-Cys-2MNA (h) > PAA100-Cys-2MNA (h) on both Caco-2 cell monolayers and rat intestinal mucosa. Comparing the influence of degree of preactivation with 2MNA on permeation enhancement, the following order PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (m) ≈ PAA450-Cys-2MNA (l) on Caco-2 cell monolayers and PAA450-Cys-2MNA (m) > PAA450-Cys-2MNA (h) > PAA450-Cys-2MNA (l) on intestinal mucosa was observed. The Papp of sodium fluorescein was 5.08-fold improved on Caco-2 cell monolayers for PAA450-Cys-2MNA (h) and 2.46-fold improved on intestinal mucosa for PAA450-Cys-2MNA (m), respectively, in comparison to sodium fluorescein in buffer only. These results indicated that preactivated thiomers could be considered as a promising macromolecular permeation enhancing polymer for non-invasive drug administration. PMID:22960503

  11. 49 CFR 173.175 - Permeation devices.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Permeation devices. 173.175 Section 173.175... Permeation devices. Permeation devices that contain hazardous materials and that are used for calibrating air quality monitoring devices are not subject to the requirements of this subchapter provided the...

  12. Water permeation through organic materials

    NASA Astrophysics Data System (ADS)

    Doughty, D. H.; West, I. A.

    1981-09-01

    Atmospheric moisture is routinely excluded from weapon systems by the use of elastomer seals at assembly joints and electrical feedthroughs while internal moisture is minimized by relying on desiccants and on pre-dried components assembled in special low humidity assembly rooms. Published values of the water permeation coefficient for ethylene-propylene rubber and other o-ring materials are subject to some variability and the effects of aging on water permability are unknown. We have thus devised a new and extremely sensitive method for measuring moisture permeation coefficients in organic materials. This method uses dilute tritiated water as a tracer and it is approximately two orders of magnitude more sensitive than other methods. We are therefore able to make measurements on materials under STS temperature and humidity conditions. Rate data showing the approach to equilibrium and water permeability values for a variety of elastomers are presented. The test apparatus is also described.

  13. Folpet permeation through nitrile gloves.

    PubMed

    Zainal, H; Que Hee, Shane S

    2003-09-01

    The aim of this study was to investigate whether two different brands of unsupported and unlined nitrile gloves protected against aqueous emulsions of a Folpet wettable powder (50% Folpet) using an ASTM type-I-PTC 600 permeation cell at 30.0 +/- 0.1 degrees C held in a shaking water bath. An analytical method to determine Folpet using the internal standard method was first developed based on gas chromatography-mass spectrometry (GC-MS), and gas chromatography-electron capture detection (GC-ECD). A novel pyrolysis GC-ECD technique that quantified the thermal degradation product phthalimide had pg sensitivity suitable to detect the trace amounts of Folpet that permeated. The on-column conversion was (68.0 +/- 9.5) percent at 170 degrees C over the folpet injected mass range of 3 to 148 pg. The challenge solution in the permeation cell was 1.4 mg/mL aqueous emulsion of Folpet wettable powder, and 2-propanol was the collection solvent. After evaporation of the collection solvent, the time weighted average rate of permeation of Folpet through SafeSkin nitrile (an exams type of glove) after 8 hours was (42.1 +/- 2.9) ng/cm(2)/min compared with (2.04 +/- 0.69) ng/cm(2)/min for the Sol-Vex nitrile (industrial chemical resistant), the latter being about 21 times more protective and also near the limits of detection. The respective values after 4 hours of exposure were (28.4 +/- 1.2) and (0.65 +/- 0.36) ng/cm(2)/min. Diagnostic reflectance infrared minima of both challenge and collection sides of the gloves showed small changes in wave number and intensity values after 8 hours of exposure, with Folpet being detected in dried spots on the challenge side. GC-ECD-based permeation and IR reflectance data indicated high chemical resistance of the Sol-Vex gloves to an aqueous emulsion of Folpet. PMID:12909534

  14. Apparatus and methods for detecting chemical permeation

    DOEpatents

    Vo-Dinh, Tuan

    1994-01-01

    Apparatus and methods for detecting the permeation of hazardous or toxic chemicals through protective clothing are disclosed. The hazardous or toxic chemicals of interest do not possess the spectral characteristic of luminescence. The apparatus and methods utilize a spectrochemical modification technique to detect the luminescence quenching of an indicator compound which upon permeation of the chemical through the protective clothing, the indicator is exposed to the chemical, thus indicating chemical permeation.

  15. Dynamic moisture permeation through clothing.

    PubMed

    Kakitsuba, N; Gaul, K; Michna, H; Mekjavic, I B

    1988-01-01

    Dynamic moisture permeation through clothing often occurs during thermal transience, causing an imbalance between evaporative heat loss from the skin (Esk) and that from the clothing surface (Ecl). A device was designed to observe Esk and Ecl simultaneously. It consists of two relative humidity sensors coupled with thermistors so that densities of water vapor at two points within the boundary layer can be calculated. The rate of local evaporation is then estimated from Fick's law of diffusion. Local evaporation rates from the skin and clothing surface at the chest, arm, and thigh were measured during exposure to controlled ambient temperatures varying from 20 degrees-40 degrees C. The subjects wore four different types of helicopter pilot suits: Nomex/Neoprene, Goretex, cotton ventile, and Nomex/Insulite. For the Goretex and cotton ventile suits, consisting of relatively permeable and hygroscopic fabrics, a sudden increase in Esk, exponential decay of Esk, and a gradual increase in Ecl were observed. These appear to be associated with, respectively, the onset of sweat secretion, moisture build-up within the clothing, and water gain in the fabric. Thus, the device may be useful for observing dynamic moisture permeation through clothing. PMID:3355466

  16. Effect of iontophoresis and permeation enhancers on the permeation of an acyclovir gel.

    PubMed

    Vaghani, Subhash S; Gurjar, Mitesh; Singh, Sachin; Sureja, Sunil; Koradia, Shailesh; Jivani, N P; Patel, M M

    2010-10-01

    The purpose of the present study was to explore the combined effect of chemical enhancers and iontophoresis on the in vitro permeation of acyclovir gel across porcine skin. Acyclovir gel was formulated using carbopol 940 and hydroxypropyl methylcellulose K4M (HPMC K4M). Effect of drug concentration on the delivery of acyclovir was examined. Increasing drug concentration of acyclovir enhanced its flux across the skin. Incorporation of permeation enhancers (menthol, n-methyl-2-pyrrolidone and polyethylene glycol 400) into the gel resulted in enhanced acyclovir permeation when combined with iontophoresis. Menthol showed the highest drug permeation and when combined with iontophoresis it significantly increased the acyclovir skin permeation. PMID:20695844

  17. Apparatus and methods for detecting chemical permeation

    DOEpatents

    Vo-Dinh, T.

    1994-12-27

    Apparatus and methods for detecting the permeation of hazardous or toxic chemicals through protective clothing are disclosed. The hazardous or toxic chemicals of interest do not possess the spectral characteristic of luminescence. The apparatus and methods utilize a spectrochemical modification technique to detect the luminescence quenching of an indicator compound which upon permeation of the chemical through the protective clothing, the indicator is exposed to the chemical, thus indicating chemical permeation. The invention also relates to the fabrication of protective clothing materials. 13 figures.

  18. Protective glove material permeation by organic solids.

    PubMed

    Fricker, C; Hardy, J K

    1992-12-01

    A method has been developed for the determination of permeation characteristics of glove materials by organic solids. The system employs a stainless steel exposure cell and allows rapid and uniform contact of either solid disks or powders with minimal membrane bowing. A gas chromatograph equipped with a flame ionization detector was used for monitoring the permeation process, which provided detection limits of 0.9-1.2 ng for the organic solids evaluated. By using an automated system for instrument control and data collection, breakthrough times, steady-state times, and steady-state permeation rates have been determined for five common glove materials when exposed to nine organic solids. PMID:1471595

  19. Opto-acoustic cell permeation

    SciTech Connect

    Visuri, S R; Heredia, N

    2000-03-09

    Optically generated acoustic waves have been used to temporarily permeate biological cells. This technique may be useful for enhancing transfection of DNA into cells or enhancing the absorption of locally delivered drugs. A diode-pumped frequency-doubled Nd:YAG laser operating at kHz repetition rates was used to produce a series of acoustic pulses. An acoustic wave was formed via thermoelastic expansion by depositing laser radiation into an absorbing dye. Generated pressures were measured with a PVDF hydrophone. The acoustic waves were transmitted to cultured and plated cells. The cell media contained a selection of normally- impermeable fluorescent-labeled dextran dyes. Following treatment with the opto-acoustic technique, cellular incorporation of dyes, up to 40,000 Molecular Weight, was noted. Control cells that did not receive opto-acoustic treatment had unremarkable dye incorporation. Uptake of dye was quantified via fluorescent microscopic analysis. Trypan Blue membrane exclusion assays and fluorescent labeling assays confirmed the vitality of cells following treatment. This method of enhanced drug delivery has the potential to dramatically reduce required drug dosages and associated side effects and enable revolutionary therapies.

  20. Electret enhances transdermal drug permeation.

    PubMed

    Narasimha Sathyanarayana Murthy, Narasimha Sathyanarayana; Boguda, Vishwanath Anantharamaiah; Payasada, Kotrappa

    2008-01-01

    Electrets are polymeric discs that carry semi permanent electrostatic charge. These provide electrostatic potentials in the range of 500 to 3,000 V. In the current work, the effect of electret exposure on the skin permeability was investigated. Transdermal transport studies were carried out across porcine epidermis in Franz diffusion cells. Salicylic acid, fluorescein labeled dextrans (FD) and propofol were used as test diffusants. The ability of electret to enhance the transdermal permeation of salicylic acid was studied in vivo in Sprague Dawley rats. Electret enhanced the permeability of porcine epidermis to salicylic acid. The enhancement factor increased with the surface voltage, however it was independent of the nature of charge (+ or -). The enhancement by electret was cut-off at 1 kDa, as interpreted by studying the transport of FD. The electrets decreased the permeability of skin to propofol, a lipophilic diffusant. Pretreatment of porcine epidermis enhanced the iontophoretic transport of salicylic acid, whereas the same did not enhance the transport of salicylic acid by electroporation. It is most likely that electret exposure renders the lipid domains of stratum corneum more permeable to polar molecules and in turn hampers the diffusion of nonpolar diffusant. PMID:18175950

  1. The use of permeation tube device and the development of empirical formula for accurate permeation rate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of laboratory experiments were conducted to assess the accuracy of permeation tube (PT) devices using a calibration gas generator system to measure permeation rate (PR) of volatile organic compounds (VOCs). Calibration gas standards of benzene, toluene, and m-xylene (BTX) were produced from...

  2. Preparation, characterization and buccal permeation of naratriptan.

    PubMed

    Sattar, Mohammed; Hadgraft, Jonathan; Lane, Majella E

    2015-09-30

    Naratriptan (NAR) is currently used for the management of migraine as the hydrochloride salt (NAR.HCl) and is administered as an oral tablet. This work evaluates the feasibility of buccal delivery of NAR in order to ensure faster onset of action and avoid the side-effects associated with conventional oral formulations. We hypothesized that the unionized form of NAR would permeate buccal tissue to a greater extent than the salt. Therefore the first stage of this work required preparation of the free base from NAR.HCl. Characterisation of the base with thermal and elemental analyses confirmed its purity; logP and logD values were also determined. The pH permeation profile of NAR was also determined in the range 7.4-10. Solubility studies in non-aqueous solvents indicated that Transcutol™ (TC) and dipropylene glycol (DPG) were suitable vehicles for the free base. Maximum amounts of NAR which permeated after 6h were ∼ 130 μg/cm(2). Based on the pH permeation results and studies conducted at two different doses NAR appears to permeate porcine buccal tissue via the transcellular route. Finally, estimates of likely systemic values suggest that optimised formulations should be taken forward for in vivo evaluation. PMID:26196276

  3. Deuterium permeation through copper with trapping impurities

    NASA Astrophysics Data System (ADS)

    Mitchell, D. J.; Harris, J. M.; Patrick, R. C.; Boespflug, E. P.; Beavis, L. C.

    1982-02-01

    The time dependence of the deuterium permeation rate through impurity-doped copper membranes was measured in the temperature range 300-700 °C. Copper membranes that were doped with Er, Zr, and Ti all exhibited permeabilities that were nearly equal to pure copper, but the apparent diffusivities were smaller than those for pure copper by factors of 10-100 over the experimental temperature range. The permeation characteristics of these alloys appear to be altered from those for pure copper due to trapping of deuterium at sites that are associated with the impurity atoms. It is shown that the deuterium permeation rate through the copper alloys can be expressed in an analytical form that is analogous to that for pure copper, except that the apparent diffusivity takes on a value which depends on the trap concentration and binding energy for deuterium. The binding energies that are calculated for the alloys are used to determine the lag time which is required for deuterium or hydrogen to permeate through initially evacuated membranes. The lag times for copper alloys containing about 1% Er, Zr, or Ti are many orders of magnitude longer than for pure copper at room temperature. Copper alloys containing Cr do not appear to exhibit deuterium trapping. Nuclear reaction and backscattering analyses were used to help determine the effect or surface oxides on the permeation measurements.

  4. Development of Tritium Permeation Analysis Code (TPAC)

    SciTech Connect

    Eung S. Kim; Chang H. Oh; Mike Patterson

    2010-10-01

    Idaho National Laboratory developed the Tritium Permeation Analysis Code (TPAC) for tritium permeation in the Very High Temperature Gas Cooled Reactor (VHTR). All the component models in the VHTR were developed and were embedded into the MATHLAB SIMULINK package with a Graphic User Interface. The governing equations of the nuclear ternary reaction and thermal neutron capture reactions from impurities in helium and graphite core, reflector, and control rods were implemented. The TPAC code was verified using analytical solutions for the tritium birth rate from the ternary fission, the birth rate from 3He, and the birth rate from 10B. This paper also provides comparisons of the TPAC with the existing other codes. A VHTR reference design was selected for tritium permeation study from the reference design to the nuclear-assisted hydrogen production plant and some sensitivity study results are presented based on the HTGR outlet temperature of 750 degrees C.

  5. Modeling organic solvents permeation through protective gloves.

    PubMed

    Chao, Keh-Ping; Wang, Ven-Shing; Lee, Pak-Hing

    2004-02-01

    Several researchers have studied the diffusion of organic solvents through chemical protective gloves and have estimated the diffusion coefficients by using various models. In this study, permeation experiments of benzene, toluene, and styrene through nitrile and Neoprene gloves were conducted using the ASTM F-739 standard test method. The diffusion coefficients were estimated using several models from the literature. Using a one-dimensional diffusion equation based on Fick's second law and the estimated diffusion coefficients, the permeation concentrations were simulated and compared with the experimental results. The modeling results indicated that the solubility of the solvent in the glove materials obtained by immersion tests was not an appropriate boundary condition for organic solvent permeation through the polymer gloves. The modeling work of this study will assist industrial hygienists to assess exposure of chemicals to workers through the chemical protective gloves. PMID:15204879

  6. Mechanisms of gas permeation through polymer membranes

    SciTech Connect

    Stern, S.A.

    1991-01-01

    The objective of the present study is to investigate the mechanisms of gas transport in and through polymer membranes and the dependence of these mechanisms on pressure and temperature. This information is required for the development of new, energy-efficient membrane processes for the separation of industrial gas mixtures. Such processes are based on the selective permeation of the components of gas mixtures through nonporous polymer membranes. Recent work has been focused on the permeation of gases through membranes made from glassy polymers, i.e., at temperatures below the glass transition of the polymers (Tg). Glassy polymers are very useful membrane materials for gas separations because of their high selectivity toward different gases. Gases permeate through nonporous polymer membranes by a solution-diffusion'' process. Consequently, in order to understand the characteristics of this process it is necessary to investigate also the mechanisms of gas solution and diffusion in glassy polymers. 23 refs., 10 figs., 4 tabs.

  7. Permeation of polymeric materials by toluene

    SciTech Connect

    Vahdat, N.

    1987-02-01

    The permeation of toluene through protective clothing materials composed of butyl, butyl-coated nomex, neoprene, and polyvinyl alcohol was tested at 25/sup 0/C and 45/sup 0/C with the use of ASTM method F-739. Butyl exhibited breakthrough of 18 min at 25/sup 0/C and 11 min at 45/sup 0/ C. Butyl nomex exhibited breakthrough times of 11 min and 25/sup 0/C and 6 min at 45/sup 0/C. PVA showed no breakthrough in 20 hr. The steady-state permeation rates and the diffusion coefficients were determined.

  8. Permeation of Comite through protective gloves.

    PubMed

    Zainal, Hanaa; Que Hee, Shane S

    2006-09-01

    The goal of the study was to assess how protective disposable (Safeskin) and chemical protective (Sol-Vex) nitrile gloves were against Comite emulsifiable concentrate formulation containing propargite (PROP) as active pesticidal ingredient, because there were no explicit recommendations for the gloves that should be worn for hand protection. The glove material was exposed in ASTM-type I-PTC-600 permeation cells at 30.0+/-0.5 degrees C, and gas chromatography-mass spectrometry used for PROP analysis. Aqueous solutions of Comite at 40.4 mg/mL permeated both Safeskin and Sol-Vex nitrile by 8h. Safeskin showed a mean PROP mass permeated of 176+/-27 microg after 8h compared with a mean mass permeated for Sol-Vex of 3.17+/-4.08 microg. Thus, Sol-Vex was about 56 times more protective than Safeskin for an 8-h exposure. However, the kinetics of the permeation revealed that Safeskin can be worn for at least 200 min before disposal. When undiluted Comite challenged both types of nitrile, much faster permeation was observed. Safeskin gloves showed two steady state periods. The first had lag times (t(l)) values of about 1h, although normalized breakthrough times (t(b)) were < 10 min. The second steady state rate (P(s)) was on average four times the rate of the first period, and the second steady state period t(l) was about three times as long as that of the first steady state period, and about the same t(l) as for the aqueous solution. Sol-Vex gloves exposed continuously to undiluted Comite permeated above the normalized breakthrough threshold beyond 2.7h. A risk assessment revealed that the PROP skin permeation rate of 7.1 ng cm(-2)h(-1) was much slower than the first steady state Safeskin glove P(s) of 62,000 ng cm(-2)h(-1). Infrared analysis showed that the glove surfaces were not degraded by the Comite challenge. The chemically protective Sol-Vex gloves protected adequately against undiluted formulation for about 2.7h, whereas they provided protection for nearly 8h when

  9. 49 CFR 173.175 - Permeation devices.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...; (v) One drop on a corner at the junction of three intersecting edges; and (2) A force applied to the... 30 kg. (g) For transportation by aircraft, permeation devices must be transported as cargo and may... placed in a sealed, high impact resistant, tubular inner packaging of plastic or equivalent...

  10. 49 CFR 173.175 - Permeation devices.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...; (v) One drop on a corner at the junction of three intersecting edges; and (2) A force applied to the... 30 kg. (g) For transportation by aircraft, permeation devices must be transported as cargo and may... placed in a sealed, high impact resistant, tubular inner packaging of plastic or equivalent...

  11. Gel Permeation Chromatography of Fluoroether Polymers

    NASA Technical Reports Server (NTRS)

    Korus, Roger A.; Rosser, Robert W.

    1978-01-01

    A Method is described for determining the molecular weight distribution of fluorinated polymers by gel permeation chromatography. Porous silica-packed columns are used with Freon 113 as the chromatographic solvent. Fluoroether oligomers are used for column calibration in the molecular weight range of 1400 to 12000.

  12. Permeation of deuterium implanted into vanadium alloys

    SciTech Connect

    Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

    1986-05-01

    Permeation of deuterium through the vanadium alloy, V-15Cr-5Ti, was investigated using 3-keV, D/sub 3//sup +/ ion beams from a small accelerator. The experiments consisted of measurements of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5-mm thick specimens heated to tempertures from 623 to 823/sup 0/K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). Analyses of these measurements indicate that for the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This corresponds to approximately 1000 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates D = 1.4 x 10/sup -8/ exp(-.11 eV/kT) (m/sup 2//s).

  13. Permeating the Culture of a State Association

    ERIC Educational Resources Information Center

    Reeves, Pat

    2009-01-01

    In the four years since Courageous Journey was launched, the impact has permeated the Michigan Association of School Administrators (MASA). Already, 16 of 47 council and executive board members have joined a cohort. The Courageous Journey's Seven Points of Learning (or seven major superintendent responsibilities) help frame the organization's…

  14. PERMEATION OF MULTIFUNCTIONAL ACRYLATES THROUGH THREE PROTECTIVE CLOTHING MATERIALS

    EPA Science Inventory

    Permeation tests were conducted with trimethylolpropane triacrylate TMPTA), 1,6-hexanediol diacrylate (HDDA), and two mixtures of 1,6-hexanediol diacrylate with 2-ethylhexyl acrylate (EHA) to better understand the permeation behavior of multifunctional acrylate compounds. he test...

  15. Permeation of chlorothalonil through nitrile gloves: collection solvent effects in the closed-loop permeation method.

    PubMed

    Que Hee, Shane S; Zainal, Hanaa

    2010-07-15

    The aim was to measure the permeation of the fungicide chlorothalonil from Bravo Ultrex through disposable (Safeskin) and chemically protective (Solvex) nitrile glove materials in a closed-loop ASTM type permeation cell system employing different collection side solvents. The permeated fungicide was measured in the collection medium by the internal standard method through capillary gas chromatography-mass spectrometry and selective ion monitoring using m/z 222 (internal standard 4,4'-dichlorobiphenyl), and 224 and 226 (chlorothalonil). The permeated glove materials did not show swelling or shrinkage and infrared reflectance changes. Different permeated masses for the same glove material for aqueous emulsion challenges of 2.2 mg/mL Bravo Ultrex for 8 h were observed for different solvents with isopropanol>hexane>water for Safeskin, and isopropanol=hexane>water for Solvex. Solvex gloves always permeated less than Safeskin gloves for the same challenge time. When challenges with solid Bravo Ultrex occurred, chlorothalonil was still found in the collection side in the same solvent order as for the aqueous emulsion challenges, with Solvex always less than Safeskin for the same collection solvent and same challenge time. Kinetic experiments showed isopropanol was not a suitable collection solvent for Safeskin for 4 and 8 h. Hexane was not a valid collection solvent for Solvex and Safeskin for 8 h, but was better than isopropanol. PMID:20334969

  16. Permeation of chemical protective clothing by three binary solvent mixtures

    SciTech Connect

    Mickelsen, R.L.; Roder, M.M.; Berardinelli, S.P.

    1986-04-01

    An evaluation of glove materials against three different binary chemical mixtures selected from common industrial solvents was conducted. Changes in breakthrough time and permeation rate of the mixture components were evaluated as a function of the mixture composition. An increase in employee risk resulting from early mixture breakthrough time and enhanced mixture permeation rate over that of the pure chemicals was demonstrated. The permeation of a binary mixture through chemical protective clothing could not be predicted by the permeation results of the pure components. It is recommended that chemical protective clothing be tested for its permeation characteristics with the use of the chemical mixtures and conditions that reflect the work site exposure.

  17. Ultimate permeation across atomically thin porous graphene.

    PubMed

    Celebi, Kemal; Buchheim, Jakob; Wyss, Roman M; Droudian, Amirhossein; Gasser, Patrick; Shorubalko, Ivan; Kye, Jeong-Il; Lee, Changho; Park, Hyung Gyu

    2014-04-18

    A two-dimensional (2D) porous layer can make an ideal membrane for separation of chemical mixtures because its infinitesimal thickness promises ultimate permeation. Graphene--with great mechanical strength, chemical stability, and inherent impermeability--offers a unique 2D system with which to realize this membrane and study the mass transport, if perforated precisely. We report highly efficient mass transfer across physically perforated double-layer graphene, having up to a few million pores with narrowly distributed diameters between less than 10 nanometers and 1 micrometer. The measured transport rates are in agreement with predictions of 2D transport theories. Attributed to its atomic thicknesses, these porous graphene membranes show permeances of gas, liquid, and water vapor far in excess of those shown by finite-thickness membranes, highlighting the ultimate permeation these 2D membranes can provide. PMID:24744372

  18. Hydrogen Permeation in Nanostructured Bainitic Steel

    NASA Astrophysics Data System (ADS)

    Kazum, Oluwole; Beladi, Hossein; Timokhina, Ilana B.; He, Yinghe; Bobby Kannan, M.

    2016-07-01

    Hydrogen permeation of nanostructured bainitic steel, produced at two different transformation temperatures, i.e., 473.15 K (200 °C) BS-200 and 623.15 K (350 °C) BS-350, was determined using Devanathan-Stachurski hydrogen permeation cell and compared with that of mild steel. Nanostructured bainitic steel showed lower effective diffusivity of hydrogen as compared to the mild steel. The BS-200 steel, which exhibited higher volume fraction of bainitic ferrite phase, showed lower effective diffusivity than BS-350 steel. The finer microstructural constituents (bainitic ferrite laths and retained austenite films) and higher dislocation density in the bainitic ferrite phase of BS-200 steel can be attributed to its lower effective diffusivity as compared to BS-350 steel and mild steel.

  19. Molecular simulation of nonfacilitated membrane permeation.

    PubMed

    Awoonor-Williams, Ernest; Rowley, Christopher N

    2016-07-01

    This is a review. Non-electrolytic compounds typically cross cell membranes by passive diffusion. The rate of permeation is dependent on the chemical properties of the solute and the composition of the lipid bilayer membrane. Predicting the permeability coefficient of a solute is important in pharmaceutical chemistry and toxicology. Molecular simulation has proven to be a valuable tool for modeling permeation of solutes through a lipid bilayer. In particular, the solubility-diffusion model has allowed for the quantitative calculation of permeability coefficients. The underlying theory and computational methods used to calculate membrane permeability are reviewed. We also discuss applications of these methods to examine the permeability of solutes and the effect of membrane composition on permeability. The application of coarse grain and polarizable models is discussed. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov. PMID:26706099

  20. Pressure swing permeation: Novel process for gas separation by membranes

    SciTech Connect

    Feng, X.; Pan, C.Y.; Ivory, J.

    2000-04-01

    A novel process for gas separation, called pressure swing permeation, was investigated to elevate the relatively low permeate pressure by pressurization with high-pressure feed gas, thereby reducing or eliminating additional permeate compression costs where a pressurized permeate is required. This process uses two or more membrane modules and operates in a cyclic fashion, with each module repeatedly undergoing the sequential steps of feed admission and permeation, residual removal, permeate reception, permeate pressurization, and product withdrawal. The unsteady-state permeation associated with pressure swing permeation was studied parametrically, and a bench-scale unit compromising two hollow-fiber membrane modules in parallel was tested for H{sub 2}/N{sub 2} separation to demonstrate the effectiveness of the process. The permeate product at a pressure as high as the feed pressure can be produced without using a compressor. This is impossible with traditional steady-state processes where a pressure differential across the membrane must be maintained. The pressure swing permeation is analogous to pressure swing adsorption and has the potential to be synergistically integrated with the pressure swing adsorption process for enhanced separation of gases.

  1. Permeation of captan through disposable nitrile glove.

    PubMed

    Phalen, R N; Que Hee, Shane S

    2003-06-27

    The purpose of this study was to investigate the permeation of an aqueous emulsion of the pesticide, captan, as a wettable powder (48.9% captan) through a disposable nitrile glove material using an American Society for Testing and Materials (ASTM)-type I-PTC-600 permeation cell. The goal was to investigate the protective capability of the gloves against dermatitis. The analytical method was based on gas chromatography-mass spectrometry (GC-MS) and gas chromatography-electron capture detection (GC-ECD). The least quantifiable limit (LQL) was 6 ng for GC-ECD and 30 ng for GC-MS. Testing was conducted using the ASTM F739 closed-loop permeation method and a worst-case aqueous concentration 217 mg/ml of captan 50-WP. The average permeation rates were low, with 12+/-5 ng/(cm(2)min) after 2h, 50+/-25 ng/(cm(2)min) after 4h, and 77+/-58 ng/(cm(2)min) after 8h. The calculated diffusion coefficient was (1.28+/-0.10) x 10(-5)cm(2)/h. No significant swelling or shrinkage occurred at P

  2. Why can hydrogen sulfide permeate cell membranes?

    PubMed

    Riahi, Saleh; Rowley, Christopher N

    2014-10-29

    The high membrane permeability of H2S was studied using polarizable molecular dynamics simulations of a DPPC lipid bilayer. The solubility-diffusion model predicts permeability coefficients of H2S and H2O that are in good agreement with experiment. The computed diffusion coefficient profile shows H2S to diffuse at a lower rate than H2O, but the barrier for H2S permeation on the Gibbs energy profile is negligible. The hydrophobicity of H2S allows it to partition into the paraffinic interior of the membrane readily. PMID:25323018

  3. Organic fluid permeation through fluoropolymer membranes

    SciTech Connect

    Nemser, Stuart M.; Kosaraju, Praveen; Bowser, John

    2015-07-14

    Separation of the components of liquid mixtures is achieved by contacting a liquid mixture with a nonporous membrane having a fluoropolymer selectively permeable layer and imposing a pressure gradient across the membrane from feed side to permeate side. Unusually high transmembrane flux is obtained when the membrane is subjected to one or more process conditions prior to separation. These include (a) leaving some residual amount of membrane casting solvent in the membrane, and (b) contacting the membrane with a component of the mixture to be separated for a duration effective to saturate the membrane with the component.

  4. Glutaraldehyde permeation: choosing the proper glove.

    PubMed

    Jordan, S L; Stowers, M F; Trawick, E G; Theis, A B

    1996-04-01

    Six different gloves were tested with five different aqueous glutaraldehyde formulations to determine each glove's resistance to permeation. When tested against 2% or 3.4% glutaraldehyde solutions, nitrile rubber, butyl rubber, a synthetic surgical glove, and polyethylene were each impermeable for at least 4 hours. The two latex gloves tested showed glutaraldehyde breakthrough at 45 minutes. When the latex gloves were doubled, the time to first breakthrough increased to 3 to 4 hours. With 50% glutaraldehyde, only butyl rubber and nitrile rubber were impermeable for extended periods. The surgical synthetic glove had breakthrough at 1 hour, whereas polyethylene and the two latex gloves had breakthrough in less than 1 hour. PMID:8731028

  5. Hydrogen permeation resistant layers for liquid metal reactors

    SciTech Connect

    McGuire, J.C.

    1980-03-01

    Reviewing the literature in the tritium diffusion field one can readily see a wide divergence in results for both the response of permeation rate to pressure, and the effect of oxide layers on total permeation rates. The basic mechanism of protective oxide layers is discussed. Two coatings which are less hydrogen permeable than the best naturally occurring oxide are described. The work described is part of an HEDL-ANL cooperative research program on Tritium Permeation in Liquid Metal Cooled Reactors. This includes permeation work on hydrogen, deuterium, and tritium with the hydrogen-deuterium research leading to the developments presented.

  6. IN-SITU MEASUREMENT OF TRITIUM PERMEATION THROUGH STAINLESS STEEL

    SciTech Connect

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin; Longhurst, Glen R.

    2013-06-01

    The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292° and 330°C. In-situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. An irradiation enhancement factor (IEF) was determined by comparing in-situ permeation data with a correlation for ex-reactor hydrogen permeation through austenitic stainless steel developed from literature data and reported by Le Claire. Nominal values for the IEF ranged between 3 and 5 for 316 SS. In-situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330°C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

  7. In situ measurement of tritium permeation through stainless steel

    SciTech Connect

    Walter G. Luscher; David J. Senor; Kevin K. Clayton; Glen R. Longhurst

    2013-06-01

    The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292 degrees C and 330 degrees C. In situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330 degrees C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

  8. In Situ Measurement of Tritium Permeation Through Stainless Steel

    SciTech Connect

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin; Longhurst, Glen

    2013-06-01

    The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292° and 330°C. In-situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. An irradiation enhancement factor (IEF) was determined by comparing in-situ permeation data with a correlation for ex-reactor hydrogen permeation through austenitic stainless steel developed from literature data and reported by Le Claire. Nominal values for the IEF ranged between 3 and 5 for 316 SS. In-situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330°C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

  9. Rate of permeation of isotopes through human dentin, in vitro.

    PubMed

    Pashley, D H; Livingston, M J; Outhwaite, W C

    1977-01-01

    A simple in vitro method has been described for quantitatively measuring the rate at which isotopically labeled substances permeate through dentin in occlusal cavity preparations. The presence or absence of pulp tissue had only a minor effect on the kinetics of permeation. As the dentin was made thinner there was a resulting increase in the rate of iodide permeation. The relative rates of permeation were 3H2O greater than 131I greater than 99mTc greater than 14C-urea, a sequence that follows the molecular dimensions of these substances. PMID:264870

  10. In situ measurement of tritium permeation through stainless steel

    NASA Astrophysics Data System (ADS)

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2013-06-01

    The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a 4He carrier gas mixed with a specified quantity of tritium (T2) to yield partial pressures of 0.1, 5, and 50 Pa at 292 °C and 330 °C. In situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of 3He to T, was also evaluated by introducing a 4He carrier gas mixed with 3He at a partial pressure of 1013 Pa at 330 °C. Less than 3% of the tritium resulting from 3He transmutation contributed to tritium permeation.

  11. Energetics of water permeation through fullerene membrane

    PubMed Central

    Isobe, Hiroyuki; Homma, Tatsuya; Nakamura, Eiichi

    2007-01-01

    Lipid bilayer membranes are important as fundamental structures in biology and possess characteristic water-permeability, stability, and mechanical properties. Water permeation through a lipid bilayer membrane occurs readily, and more readily at higher temperature, which is largely due to an enthalpy cost of the liquid-to-gas phase transition of water. A fullerene bilayer membrane formed by dissolution of a water-soluble fullerene, Ph5C60K, has now been shown to possess properties entirely different from those of the lipid membranes. The fullerene membrane is several orders of magnitude less permeable to water than a lipid membrane, and the permeability decreases at higher temperature. Water permeation is burdened by a very large entropy loss and may be favored slightly by an enthalpy gain, which is contrary to the energetics observed for the lipid membrane. We ascribe this energetics to favorable interactions of water molecules to the surface of the fullerene molecules as they pass through the clefts of the rigid fullerene bilayer. The findings provide possibilities of membrane design in science and technology. PMID:17846427

  12. Permeation through the CFTR chloride channel.

    PubMed

    McCarty, N A

    2000-07-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) protein forms a Cl(-) channel found in the plasma membranes of many epithelial cells, including those of the kidney, gut and conducting airways. Mutation of the gene encoding CFTR is the primary defect in cystic fibrosis, a disease that affects approximately 30 000 individuals in the United States alone. Alteration of CFTR function also plays an important role in the pathophysiology of secretory diarrhea and polycystic kidney disease. The basic mechanisms of permeation in this channel are not well understood. It is not known which portions of the protein contribute to forming the pore or which amino acid residues in those domains are involved in the biophysical processes of ion permeation. In this review, I will discuss (i) the present understanding of ion transport processes in the wild-type CFTR channel, (ii) the experimental approaches currently being applied to investigate the pore, and (iii) a proposed structure that takes into account the present data on mechanisms of ion selectivity in the CFTR channel and on blockade of the pore by open-channel blockers. PMID:10851114

  13. Testing Physical Models of Passive Membrane Permeation

    PubMed Central

    Leung, Siegfried S. F.; Mijalkovic, Jona; Borrelli, Kenneth; Jacobson, Matthew P.

    2012-01-01

    The biophysical basis of passive membrane permeability is well understood, but most methods for predicting membrane permeability in the context of drug design are based on statistical relationships that indirectly capture the key physical aspects. Here, we investigate molecular mechanics-based models of passive membrane permeability and evaluate their performance against different types of experimental data, including parallel artificial membrane permeability assays (PAMPA), cell-based assays, in vivo measurements, and other in silico predictions. The experimental data sets we use in these tests are diverse, including peptidomimetics, congeneric series, and diverse FDA approved drugs. The physical models are not specifically trained for any of these data sets; rather, input parameters are based on standard molecular mechanics force fields, such as partial charges, and an implicit solvent model. A systematic approach is taken to analyze the contribution from each component in the physics-based permeability model. A primary factor in determining rates of passive membrane permeation is the conformation-dependent free energy of desolvating the molecule, and this measure alone provides good agreement with experimental permeability measurements in many cases. Other factors that improve agreement with experimental data include deionization and estimates of entropy losses of the ligand and the membrane, which lead to size-dependence of the permeation rate. PMID:22621168

  14. An unheated permeation device for calibrating atmospheric VOC measurements

    NASA Astrophysics Data System (ADS)

    Brito, J.; Zahn, A.

    2011-10-01

    The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs) is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as on board aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, so that the instantaneous permeation rate can be ascribed to a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i) a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii) a water bath as heat buffer, and (iii) a vacuum-panel based insulation, in which features (ii) and (iii) minimize temperature drifts to ~30 mK h-1 per Kelvin temperature difference to the environment. The respective uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1%. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 μm) dominates.

  15. An unheated permeation device for calibrating atmospheric VOC measurements

    NASA Astrophysics Data System (ADS)

    Brito, J.; Zahn, A.

    2011-05-01

    The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs) is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as onboard aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, i.e. the instantaneous permeation rate can be ascribed via a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i) a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii) a water bath as heat buffer, and (iii) a vacuum-panel based insulation, in which features (ii) and (iii) minimize temperature drifts. The uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1 %. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 μm) dominates.

  16. Skin permeation and metabolism of di(2-ethylhexyl) phthalate (DEHP).

    PubMed

    Hopf, N B; Berthet, A; Vernez, D; Langard, E; Spring, P; Gaudin, R

    2014-01-01

    Phthalates are suspected to be endocrine disruptors. Di(2-ethylhexyl) phthalate (DEHP) is assumed to have low dermal absorption; however, previous in vitro skin permeation studies have shown large permeation differences. Our aims were to determine DEHP permeation parameters and assess extent of skin DEHP metabolism among workers highly exposed to these lipophilic, low volatile substances. Surgically removed skin from patients undergoing abdominoplasty was immediately dermatomed (800 μm) and mounted on flow-through diffusion cells (1.77 cm(2)) operating at 32°C with cell culture media (aqueous solution) as the reservoir liquid. The cells were dosed either with neat DEHP or emulsified in aqueous solution (166 μg/ml). Samples were analysed by HPLC-MS/MS. DEHP permeated human viable skin only as the metabolite MEHP (100%) after 8h of exposure. Human skin was able to further oxidize MEHP to 5-oxo-MEHP. Neat DEHP applied to the skin hardly permeated skin while the aqueous solution readily permeated skin measured in both cases as concentration of MEHP in the receptor liquid. DEHP pass through human skin, detected as MEHP only when emulsified in aqueous solution, and to a far lesser degree when applied neat to the skin. Using results from older in vitro skin permeation studies with non-viable skin may underestimate skin exposures. Our results are in overall agreement with newer phthalate skin permeation studies. PMID:24140552

  17. Water permeation through Nafion membranes: the role of water activity.

    PubMed

    Majsztrik, Paul; Bocarsly, Andrew; Benziger, Jay

    2008-12-25

    The permeation of water through 1100 equivalent weight Nation membranes has been measured for film thicknesses of 51-254 microm, temperatures of 30-80 degrees C, and water activities (a(w)) from 0.3 to 1 (liquid water). Water permeation coefficients increased with water content in Nafion. For feed side water activity in the range 0 < a(w) < 0.8, permeation coefficients increased linearly with water activity and scaled inversely with membrane thickness. The permeation coefficients were independent of membrane thickness when the feed side of the membrane was in contact with liquid water (a(w) = 1). The permeation coefficient for a 127 microm thick membrane increased by a factor of 10 between contacting the feed side of the membrane to water vapor (a(w) = 0.9) compared to liquid water (a(w) = 1). Water permeation couples interfacial transport across the fluid membrane interface with water transport through the hydrophilic phase of Nafion. At low water activity the hydrophilic volume fraction is small and permeation is limited by water diffusion. The volume fraction of the hydrophilic phase increases with water activity, increasing water transport. As a(w) --> 1, the effective transport rate increased by almost an order of magnitude, resulting in a change of the limiting transport resistance from water permeation across the membrane to interfacial mass transport at the gas/membrane interface. PMID:19053672

  18. Permeation resistance of glove materials to agricultural pesticides.

    PubMed

    Schwope, A D; Goydan, R; Ehntholt, D; Frank, U; Nielsen, A

    1992-06-01

    The toxicities of many agricultural pesticides require that hand protection be used by persons who mix, load, and apply these products, as specified on the label and material safety data sheet. Selection of gloves for formulations that contain organic solvents is particularly problematic because a solvent that permeates the glove can carry with it the active ingredient of the pesticide formulation. With a test method that measures the simultaneous permeation of the carrier solvent(s) and active ingredient(s), in particular those active ingredients that have low solubility in water and low volatility, over 100 permeation tests (in triplicate) with approximately 20 pesticide formulations were conducted with 13 different glove materials. These results are summarized and generalizations are presented within the perspective of the large base of permeation data for neat chemicals and another large permeation study with pesticides. Key among the findings is that the carrier solvent generally permeates first and at a much higher rate than the active ingredient. Furthermore, the permeation behavior of formulations containing solvents generally mirrored that of neat carrier solvents alone. Thus, insight into the selection of the most appropriate glove material for a given pesticide formulation can be gained from permeation data for neat chemicals. For the types of solvents that may be present in pesticide formulations, preferred materials include nitrile rubber, butyl rubber, and plastic film laminates. Natural rubber and polyvinyl chloride materials generally are not recommended. PMID:1605107

  19. Electrical insulator assembly with oxygen permeation barrier

    DOEpatents

    Van Der Beck, R.R.; Bond, J.A.

    1994-03-29

    A high-voltage electrical insulator for electrically insulating a thermoelectric module in a spacecraft from a niobium-1% zirconium alloy wall of a heat exchanger filled with liquid lithium while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator has a single crystal alumina layer (SxAl[sub 2]O[sub 3], sapphire) with a niobium foil layer bonded thereto on the surface of the alumina crystal facing the heat exchanger wall, and a molybdenum layer bonded to the niobium layer to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface. 3 figures.

  20. Electrical insulator assembly with oxygen permeation barrier

    DOEpatents

    Van Der Beck, Roland R.; Bond, James A.

    1994-01-01

    A high-voltage electrical insulator (21) for electrically insulating a thermoelectric module (17) in a spacecraft from a niobium-1% zirconium alloy wall (11) of a heat exchanger (13) filled with liquid lithium (16) while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator (21) has a single crystal alumina layer (SxAl.sub.2 O.sub.3, sapphire) with a niobium foil layer (32) bonded thereto on the surface of the alumina crystal (26) facing the heat exchanger wall (11), and a molybdenum layer (31) bonded to the niobium layer (32) to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface.

  1. Hydrogen permeation through coated and uncoated WASPALOY

    NASA Astrophysics Data System (ADS)

    Perng, T. P.; Johnson, M. J.; Altstetter, C. J.

    1988-05-01

    Hydrogen permeability, diffusivity, and solubility have been measured for a Ni-base superalloy, WASPALOY,* over the temperature range of 200 to 560 °C. Measurements were made with various surface conditions. The hydrogen diffusivity and permeability values for Pd-coated WASPALOY were between those for pure nickel and for austenitic stainless steel. Hydrogen in uncoated WASPALOY had consistently lower effective diffusivity and permeability than in the Pd-coated condition. Gold-plating on WASPALOY or adding H2O to H2 gas substantially reduced both transport parameters, presumably due to slower surface or interface kinetics and lower permeability of hydrogen in the gold layer. Independently measured hydrogen solubility determined by equilibration of bulk specimens with H2 gas was roughly 60 pct of the solubility obtained by dividing the effective diffusivity into the permeation constant. This is discussed on the basis of internal trapping, which reduced the effective diffusivity and resulted in a higher apparent solubility.

  2. Permeation of Telone EC through protective gloves.

    PubMed

    Zainal, Hanaa; Que Hee, Shane S

    2005-09-30

    Telone is a potent fumigant that is based on the chlorinated unsaturated hydrocarbon, 1,3-dichloropropene (1,3-DCP). It is often applied without dilution and so poses severe inhalation and air pollution threats. Urinary metabolites of 1,3-DCP have been detected after Telone skin exposure, so that preventing dermal exposure is also important. The objective of the study was to assess if nitrile and multi-layer ("laminated") gloves provide adequate protection against Telone EC formulation. To accomplish this, disposable (Safeskin) and chemically resistant (Sol-Vex) nitrile and laminated (Barrier mark and Silver Shield) glove materials were challenged by Telone EC with hexane liquid collection in an ASTM-type I-PTC-600 permeation cell. Analyses of cis- and trans-1,3-DCP in the collection fluid at specified times were performed on a moderately polar capillary column by gas chromatography-electron capture detection. Telone EC caused microholes in both nitrile materials, though the chemically protective material was degraded slower than the disposable nitrile. The laminated gloves offered limited protection. Silver Shield protected best because 1.5-2.3 mg 1,3-DCP permeated by 8 h relative to 2.5-7.6 mg for Barrier, implying about 2.5 times more protection for 8 h. Even for Silver Shield, the extent of protection was inadequate as illustrated by a risk assessment of the skin exposure situation. The normalized breakthrough times for both types of laminated gloves varied between 27 and 60 min. It is recommended that Viton gloves still be worn for protection. PMID:15982807

  3. Permeation of aromatic solvent mixtures through nitrile protective gloves.

    PubMed

    Chao, Keh-Ping; Hsu, Ya-Ping; Chen, Su-Yi

    2008-05-30

    The permeation of binary and ternary mixtures of benzene, toluene, ethyl benzene and p-xylene through nitrile gloves were investigated using the ASTM F739 test cell. The more slowly permeating component of a mixture was accelerated to have a shorter breakthrough time than its pure form. The larger differences in solubility parameter between a solvent mixture and glove resulted in a lower permeation rate. Solubility parameter theory provides a potential approach to interpret the changes of permeation properties for BTEX mixtures through nitrile gloves. Using a one-dimensional diffusion model based on Fick's law, the permeation concentrations of ASTM F739 experiments were appropriately simulated by the estimated diffusion coefficient and solubility. This study will be a fundamental work for the risk assessment of the potential dermal exposure of workers wearing protective gloves. PMID:17977655

  4. A METHOD TO MEASURE PROTECTIVE CLOTHING PERMEATION UNDER INTERMITTENT CHEIMCAL CONTACT CONDITIONS

    EPA Science Inventory

    A preliminary method was developed to measure chemical permeation under intermittent chemical contact conditions. Protective clothing permeation is presently measured using ASTM Method F739-85. Because this test measures permeation when the clothing material is in continuous cont...

  5. Hydrogen permeation through disordered nanostructured tungsten films

    NASA Astrophysics Data System (ADS)

    Nemanič, V.; Zajec, B.; Dellasega, D.; Passoni, M.

    2012-10-01

    We report results on long-term hydrogen outgassing and permeation studies of structurally highly disordered tungsten films, deposited on 40 mm diameter highly permeable Eurofer substrates, using the Pulsed Laser Deposition technique. Hydrogen interaction with tungsten is becoming a highly relevant topic since tungsten was recognized as the most promising candidate for the first wall of future fusion reactors. Prediction of hydrogen isotopes migration and their abundance after plasma exposure is uncertain due to a great role played by structural disorder that is formed on the W surface. Vacancy sites are theoretically predicted to trap multiple H atoms exothermically, but their density and their potential influence on permeability has not been experimentally investigated yet. In our work, permeability of W films having different thicknesses (1 and 10 μm) was initially extremely low, and was gradually increasing over a several-day campaign. The final values at 400 °C, lying between P = 1.46 × 10-15 mol H2/(m s Pa0.5) and P = 4.8 × 10-15 mol H2/(m s Pa0.5), were substantially lower than those known for well ordered films. Surprisingly, the 10 μm thick W film initially contained a very high amount of hydrogen, ˜0.1 H/W, which was gradually releasing during the twenty-day campaign.

  6. Permeation absorption sampler with multiple detection

    DOEpatents

    Zaromb, Solomon

    1990-01-01

    A system for detecting analytes in air or aqueous systems includes a permeation absorption preconcentrator sampler for the analytes and analyte detectors. The preconcentrator has an inner fluid-permeable container into which a charge of analyte-sorbing liquid is intermittently injected, and a fluid-impermeable outer container. The sample is passed through the outer container and around the inner container for trapping and preconcentrating the analyte in the sorbing liquid. The analyte can be detected photometrically by injecting with the sorbing material a reagent which reacts with the analyte to produce a characteristic color or fluorescence which is detected by illuminating the contents of the inner container with a light source and measuring the absorbed or emitted light, or by producing a characteristic chemiluminescence which can be detected by a suitable light sensor. The analyte can also be detected amperometrically. Multiple inner containers may be provided into which a plurality of sorbing liquids are respectively introduced for simultaneously detecting different analytes. Baffles may be provided in the outer container. A calibration technique is disclosed.

  7. Permeation rates for RTF metal hydride vessels

    SciTech Connect

    Klein, J.E.

    1992-05-21

    Contamination rates have been estimated for the RTF nitrogen heating and cooling system (NH and CS) due to tritium permeation through the walls of metal hydride vessels. Tritium contamination of the NH and CS will be seen shortly after start-up of the RTF with the majority of it coming from the TCAP units. Contamination rates of the NH and CS are estimated to exceed 400 Ci/year after three years of operation and will elevate tritium concentrations in the NH and CS above 6 {times} 10{sup {minus}3} {mu}Ci/cc. To reduce tritium activity in the NH and CS, a stripper or ``getter`` bed may need to be installed in the NH and CS. Increasing the purge rate of nitrogen from the NH and CS is shown to be an impractical method for reducing tritium activity due to the high purge rates required. Stripping of the NH and CS nitrogen in the glove box stripper system will give a temporary lowering of tritium activity in the NH and CS, but tritium activity will return to its previous level in approximately two weeks.

  8. Permeation enhancer strategies in transdermal drug delivery.

    PubMed

    Marwah, Harneet; Garg, Tarun; Goyal, Amit K; Rath, Goutam

    2016-01-01

    Today, ∼74% of drugs are taken orally and are not found to be as effective as desired. To improve such characteristics, transdermal drug delivery was brought to existence. This delivery system is capable of transporting the drug or macromolecules painlessly through skin into the blood circulation at fixed rate. Topical administration of therapeutic agents offers many advantages over conventional oral and invasive techniques of drug delivery. Several important advantages of transdermal drug delivery are prevention from hepatic first pass metabolism, enhancement of therapeutic efficiency and maintenance of steady plasma level of the drug. Human skin surface, as a site of drug application for both local and systemic effects, is the most eligible candidate available. New controlled transdermal drug delivery systems (TDDS) technologies (electrically-based, structure-based and velocity-based) have been developed and commercialized for the transdermal delivery of troublesome drugs. This review article covers most of the new active transport technologies involved in enhancing the transdermal permeation via effective drug delivery system. PMID:25006687

  9. Experimental stand for studies of hydrogen isotopes permeation

    SciTech Connect

    Brad, S.; Stefanescu, I.; Stefan, L.; Lazar, A.; Vijulie, M.; Sofilca, N.; Bornea, A.; Vasut, F.; Zamfirache, M.; Bidica, N.; Postolache, C.; Matei, L.

    2008-07-15

    As a result of the high probability of hydrogen isotope permeation through materials used in high-temperature reactor operations, the interaction of hydrogen isotopes with metallic structural materials proposed to be used for fusion reactor designing is of great importance for safety considerations. Determining the parameters of the interaction between hydrogen isotopes and different materials, is therefore essential to accurately calculate recycling, outgassing, loading, permeation and hydrogen embrittlement. The permeation tests were made in collaboration with IFIN Bucuresti inside of a special glove-box to avail their radioactive protection expertise. This investigation programme is ongoing. In this paper we describe the permeation stand facility and the preliminary tests carried out to date. (authors)

  10. PERMEATION OF MULTIFUNCTIONAL ACRYLATES THROUGH SELECTED PROTECTIVE GLOVE MATERIALS

    EPA Science Inventory

    In support of the Premanufacture Notification (PMN) program of the Environmental Protection Agency's Office of Toxic Substances, the resistance of three glove materials to permeation by multifunctional acrylate compounds was evaluated through a program for the Office of Research ...

  11. Skin permeation of testosterone and its ester derivatives in rats.

    PubMed

    Kim, M K; Lee, C H; Kim, D D

    2000-04-01

    To establish the optimum conditions for improving the transdermal delivery of testosterone, we studied the relationship between the lipophilicity of testosterone ester derivatives and the rat skin permeation rate of testosterone. We performed a rat skin permeation study of testosterone and its commercially available ester derivatives, testosterone hemisuccinate, testosterone propionate and testosterone-17beta-cypionate, using an ethanol/water co-solvent system. The aqueous solubility and rat skin permeation rate of each drug, saturated in various compositions of an ethanol/water system, was determined at 37 degrees C. The aqueous solubility of testosterone and its ester derivatives increased exponentially as the volume fraction of ethanol increased up to 100% (v/v). The stability of testosterone propionate in both the skin homogenate and the extract was investigated to observe the enzymatic degradation during the skin permeation process. Testosterone propionate was found to be stable in the isotonic buffer solution and in the epidermis-side extract for 10h at 37 degrees C. However, in the skin homogenate and the dermis-side extract testosterone propionate rapidly degraded producing testosterone, implying that testosterone propionate rapidly degraded to testosterone during the skin permeation process. The steady-state permeation rates of testosterone in the ethanol/water systems increased exponentially as the volume fraction of ethanol increased, reaching the maximum value (2.69+/-0.69 microg cm(-2)h(-1)) at 70% (v/v) ethanol in water, and then decreasing with further increases in the ethanol volume fraction. However, in the skin permeation study with testosterone esters saturated in 70% (v/v) ethanol in water system, testosterone esters were hardly detected in the receptor solution, probably due to the rapid degradation to testosterone during the skin permeation process. Moreover, a parabolic relationship was observed between the permeation rate of testosterone and

  12. Measurement of tritium permeation through resistant materials near room temperature

    SciTech Connect

    Maienschein, J.; DuVal, V.; McMurphy, F.; Uribe, F.; Musket, R.; Brown, D.

    1985-01-01

    To measure tritium permeation through low-permeability materials at 50 to 170/sup 0/C, we use highly-sensitive liquid scintillation counting to detect the permeating tritium. To validate our method, we conducted extensive experiments with copper, for which much data exists for comparison. We report permeability of tritium through copper at 50, 100, and 170/sup 0/C, and discuss details of the experimental technique. Further plans are outlined. 15 refs., 5 figs., 1 tab.

  13. Permeation of multifunctional acrylates through selected protective glove materials.

    PubMed

    Renard, E P; Goydan, R; Stolki, T

    1992-02-01

    In support of the Premanufacture Notification (PMN) program of the Environmental Protection Agency's Office of Toxic Substances, the resistance of three glove materials to permeation by multifunctional acrylate compounds was evaluated through a program for the Office of Research and Development. Several recent PMN submissions relate to multifunctional acrylates and essentially no permeation data are available for this class of compounds. To better understand permeation behavior, tests were conducted with trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), and two mixtures of HDDA with 2-ethylhexyl acrylate (EHA). Because of the low vapor pressure and low water solubility of these compounds, the tests were conducted by using ASTM Method F739-85 with a silicone rubber sheeting material as the collection medium. Tests were performed at 20 degrees C with butyl, natural, and nitrile rubber glove materials. None of the acrylate compounds nor mixtures was found to permeate the butyl or nitrile rubber under the test conditions. Permeation through the natural rubber was observed in tests with pure HDDA, a 50% HDDA/50% EHA mixture, and a 25% HDDA/75% EHA mixture. TMPTA permeation through the natural rubber was also detected, but only in one of the triplicate tests after the 360-480 min sampling interval. For pure HDDA, the breakthrough detection time was 30-60 min and the steady-state permeation rate was 0.92 micrograms/cm2-min. For the HDDA/EHA mixtures, permeation of both mixture components was detected during the same sampling interval in each test. The breakthrough detection time was 30-60 min for the 50/50 mixture and from 15-30 to 30-60 min for the 25/75 mixture.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1543127

  14. Ammonia and ethylene oxide permeation through selected protective clothing.

    PubMed

    Berardinelli, S P; Moyer, E S; Hall, R C

    1990-11-01

    An automated permeation test system was developed to collect permeation data. Three test specimens were evaluated simultaneously versus a challenge gas. The study evaluated chemical protective clothing garment materials for use by emergency response personnel confronted by ammonia or ethylene oxide in the gas phase. A total of 13 encapsulating suit materials and 2 glove materials were tested. Surgical latex material is not recommended for use in handling ammonia or ethylene oxide; other materials offer much greater protection. PMID:2085165

  15. Surface behaviour in deuterium permeation through erbium oxide coatings

    NASA Astrophysics Data System (ADS)

    Chikada, T.; Suzuki, A.; Adelhelm, C.; Terai, T.; Muroga, T.

    2011-06-01

    Suppression of tritium permeation through structural materials is essential in order to mitigate fuel loss and radioactivity concerns. Ceramic coatings have been investigated for over three decades as tritium permeation barriers (TPBs); however, a very limited number of investigations on the mechanism of hydrogen-isotope permeation through the coatings have been reported. In this study, deuterium permeation behaviour of erbium oxide coatings fabricated by filtered arc deposition on reduced activation ferritic/martensitic steels has been investigated. The samples coated on both sides of the substrates showed remarkably lower permeability than those coated on one side, and the maximum reduction efficiency indicated a factor of 105 compared with the substrate. The different permeation behaviour between the coatings facing the high and low deuterium pressure sides has been found by the crystal structure analysis and the evaluation of the energy barriers. It is suggested that the permeation processes on the front and back surfaces are independent, and the TPB efficiency of the samples coated on both sides can be expressed by a multiplication of that of each side.

  16. Permeation of cytotoxic formulations through swatches from selected medical gloves.

    PubMed

    Klein, Michael; Lambov, Nikolai; Samev, Nikola; Carstens, Gerhard

    2003-05-15

    The permeability of selected medical glove materials to various cytotoxic agents is described. Fifteen cytotoxic agents were prepared at the highest concentrations normally encountered by hospital personnel. Four single-layer and two double-layer glove systems made of two materials--latex and neoprene--were exposed to the drugs for 30, 60, 90, 120, 150, and 180 minutes. Circular sections of the glove material were cut from the cuff and evaluated without any pretreatment. Permeability tests were conducted in an apparatus consisting of a donor chamber containing the cytotoxic solution and a collection chamber filled with water (the acceptor medium). The two sections were separated by the glove material. Permeating portions, collected in water as the acceptor medium, were analyzed by either ultraviolet-visible light spectrophotometry or high-performance liquid chromatography (HPLC). Permeation rates were calculated on the basis of the concentration of the cytotoxic agent in the acceptor medium. Spectrophotometric measurements were taken every 30 minutes, and HPLC analysis was performed at the end of the three-hour period. Average permeation rates for 14 drugs were low (< 0.2 nmol/[min.cm2]) or no permeation was detected in all glove materials. All glove materials tested were impermeable to most of the cytotoxic agents over a period of three hours. Carmustine was the only agent that substantially permeated single-layer latex glove materials. Permeation of most tested cytotoxic formulations was low through swatches of material from various medical gloves. PMID:12789871

  17. Vehicle influence on permeation through intact and compromised skin.

    PubMed

    Gujjar, Meera; Banga, Ajay K

    2014-09-10

    The purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p<0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intactpermeation into and across skin compared to mineral oil vehicle for all simulated models of compromised skin. PMID:24979534

  18. Controlled permeation of hydrogen through glass. Final report

    SciTech Connect

    Halvorson, T.; Shelby, J.E. Jr.

    1998-03-01

    Storing hydrogen inside of hollow glass spheres requires that the gas permeate through the glass walls. Hydrogen permeation through glass is relatively slow and the time to charge a sphere or bed of spheres is dependent on many factors. Permeation processes are strongly temperature dependent with behavior that follows an Arrhenius function., Rate is also dependent on the pressure drop driving force across a membrane wall and inversely proportional to thickness. Once filled, glass spheres will immediately begin to leak once the pressure driving force is reversed. Practical systems would take advantage of the fact that keeping the glass at ambient temperatures can minimize outboard leakage even with significant internal pressures. If hydrogen could be loaded and unloaded from glass microspheres with significantly less energy and particularly at near ambient temperature, some of the key barriers to commercializing this storage concept would be broken and further system engineering efforts may make this approach cost-effective. There were two key objectives for this effort. The first was to evaluate the application of hollow glass microspheres for merchant hydrogen storage and distribution and then determine the hydrogen permeation performance required for practical commercial use. The second objective was to identify, through a series of fundamental experiments, a low energy, low temperature field effect that could significantly enhance hydrogen permeation through glass without application of heat. If such an effect could be found, hollow glass microspheres could be much more attractive for hydrogen storage or possibly gas separation applications.

  19. Silicon carbide tritium permeation barrier for steel structural components.

    SciTech Connect

    Causey, Rion A.; Garde, Joseph Maurico; Buchenauer, Dean A.; Calderoni, Pattrick; Holschuh, Thomas, Jr.; Youchison, Dennis Lee; Wright, Matt; Kolasinski, Robert D.

    2010-09-01

    Chemical vapor deposited (CVD) silicon carbide (SiC) has superior resistance to tritium permeation even after irradiation. Prior work has shown Ultrametfoam to be forgiving when bonded to substrates with large CTE differences. The technical objectives are: (1) Evaluate foams of vanadium, niobium and molybdenum metals and SiC for CTE mitigation between a dense SiC barrier and steel structure; (2) Thermostructural modeling of SiC TPB/Ultramet foam/ferritic steel architecture; (3) Evaluate deuterium permeation of chemical vapor deposited (CVD) SiC; (4) D testing involved construction of a new higher temperature (> 1000 C) permeation testing system and development of improved sealing techniques; (5) Fabricate prototype tube similar to that shown with dimensions of 7cm {theta} and 35cm long; and (6) Tritium and hermeticity testing of prototype tube.

  20. Hydrogen permeation, diffusion and solubility in IN-100 and Waspaloy

    NASA Technical Reports Server (NTRS)

    Khan, A. S.; Peterson, D. T.

    1990-01-01

    An attempt has been made to determine the permeation rate of hydrogen in IN-100 and Waspaloy by determining the evolution rate of hydrogen from a closed capsule of the test materials. Enclosed vanadium hydride was the source of hydrogen in the capsule. The presentation discusses the treatment of data and assesses the validity of the techniques in permeation measurement. In addition to permeation experiments, the solubility and diffusion of hydrogen in IN-100 and Waspaloy were also determined. For hydrogen diffusion in Waspaloy, Delta H was 38.5 kJ and D(0) was 0.0026 sq cm/sec. For IN-100, Delta H was 68.2 kJ and D(0) was 0.059 sq cm /sec. Both IN-100 and Waspaloy exhibited limited solubility of hydrogen at pressures up to 340 atmospheres hydrogen.

  1. Constant pressure high throughput membrane permeation testing system

    DOEpatents

    Albenze, Erik J.; Hopkinson, David P.; Luebke, David R.

    2014-09-02

    The disclosure relates to a membrane testing system for individual evaluation of a plurality of planar membranes subjected to a feed gas on one side and a sweep gas on a second side. The membrane testing system provides a pressurized flow of a feed and sweep gas to each membrane testing cell in a plurality of membrane testing cells while a stream of retentate gas from each membrane testing cell is ported by a retentate multiport valve for sampling or venting, and a stream of permeate gas from each membrane testing cell is ported by a permeate multiport valve for sampling or venting. Back pressure regulators and mass flow controllers act to maintain substantially equivalent gas pressures and flow rates on each side of the planar membrane throughout a sampling cycle. A digital controller may be utilized to position the retentate and permeate multiport valves cyclically, allowing for gas sampling of different membrane cells over an extended period of time.

  2. Permeation of "Hydromer" Film: An Elastomeric Hydrogen-Capturing Biopolymer.

    SciTech Connect

    Karnesky, Richard A.; Friddle, Raymond William; Whaley, Josh A.; Smith, Geoffrey

    2015-12-01

    This report analyzes the permeation resistance of a novel and proprietary polymer coating for hydrogen isotope resistance that was developed by New Mexico State University. Thermal gravimetric analysis and thermal desoprtion spectroscopy show the polymer is stable thermally to approximately 250 deg C. Deuterium gas-driven permeation experiments were conducted at Sandia to explore early evidence (obtained using Brunauer - Emmett - Teller) of the polymer's strong resistance to hydrogen. With a relatively small amount of the polymer in solution (0.15%), a decrease in diffusion by a factor of 2 is observed at 100 and 150 deg C. While there was very little reduction in permeability, the preliminary findings reported here are meant to demonstrate the sensitivity of Sandia's permeation measurements and are intended to motivate the future exploration of thicker barriers with greater polymer coverage.

  3. Skin permeation of lidocaine from crystal suspended oily formulations.

    PubMed

    Matsui, Rakan; Hasegawa, Masaaki; Ishida, Masami; Ebata, Toshiya; Namiki, Noriyuki; Sugibayashi, Kenji

    2005-09-01

    In vitro permeation of lidocaine (lidocaine base, LID) through excised rat skin was investigated using several LID-suspended oily formulations. The first skin permeation of LID from an LID-suspended oily solution such as liquid paraffin (LP), isopropyl myristate (IPM), polyoxyethylene (2) oleylether (BO-2), and diethyl sebacate (DES) was evaluated and compared with that from polyethylene glycol 400 (PEG400) solution, a hydrophilic base. The obtained permeation rate of LID, Japp, from PEG400, LP, IPM, BO-2, and DES was in the order of DES>BO-2=IPM>LP>PEG400, and increased with LID solubility in the oily solvents, although LID crystals were dispersed in all solvents. Subsequently, oily formulations that consisted of different ratios of the first oily solvent (IPM, BO-2, or DES) (each 0-20%), the second oily solvent (LP) and an oily mixture of microcrystalline wax/white petrolatum/paraffin (1/5/4) were evaluated. BO-2 groups at a concentration of 5% and 10% had the highest Japp among the oily formulations, although a higher BO-2 resulted in lower skin permeation. In addition, pretreatment with BO-2 increased the skin permeation of LID. These results suggest that the penetration enhancing effect by the system may be related to the skin penetration of BO-2 itself. Finally, mathematical analysis was done to evaluate the effect of BO-2, and it was shown that BO-2 improved the LID solubility in stratum corneum lipids to efficiently enhance the LID permeation through skin. PMID:16221607

  4. Permeation Resistance of Chlorinated Polyethylene Against Hydrazine Fuels

    NASA Technical Reports Server (NTRS)

    Waller, J. M.; Williams, J. H.

    1999-01-01

    The permeation resistance of chlorinated polyethylene (CPE) used in chemical protective clothing against the aerospace fuels hydrazine, monomethylhydrazine (MMH), and uns-dimethylhydrazine (UDMH) was determined by measuring breakthrough times and time-averaged vapor transmission rates using an ASTM F 739 permeation cell. Two exposure scenarios were simulated: a 2 hour (h) fuel vapor exposure, and a liquid fuel "splash" followed by a 2 h vapor exposure. To simulate internal suit pressure during operation, a positive differential pressure of 0.3 in. water (75 Pa) on the collection side of the permeation apparatus was used. Breakthrough was observed after exposure to liquid MMH, and to vapor and liquid UDMH. No breakthrough was observed after exposure to vapor and liquid hydrazine, or vapor MMH. A model was then used to calculate propellant concentrations inside a totally encapsulating chemical protective suit based on the ASTM permeation data obtained in the present study. Concentrations were calculated under conditions of fixed vapor transmission rate, variable breathing air flow rate, and variable splash exposure area. Calculations showed that the maximum allowable permeation rates of hydrazine fuels through CPE were of the order of 0.05 to 0.08 ng sq cm/min for encapsulating suits with low breathing air flow rates (of the order of 5 scfm or 140 L/min). Above these permeation rates, the 10 parts per billion (ppb) threshold limit value time - weighted average could be exceeded for chemical protective suits having a CPE torso. To evaluate suit performance at ppb level concentrations, use of a sensitive analytical method such as cation exchange high performance liquid chromatography with amperometric detection was found to be essential.

  5. Permeation Barrier Coatings for the Helical Heat Exchanger

    SciTech Connect

    Korinko, P.S.

    1999-05-26

    A permeation barrier coating was specified for the Helical Heat Exchanger (HHE) to minimize contamination through emissions and/or permeation into the nitrogen system for ALARA reasons. Due to the geometry of the HHE, a special coating practice was needed since the conventional method of high temperature pack aluminization was intractable. A survey of many coating companies was undertaken; their coating capabilities and technologies were assessed and compared to WSRC needs. The processes and limitations to coating the HHE are described. Slurry coating appears to be the most technically sound approach for coating the HHE.

  6. In vitro permeation of platinum and rhodium through Caucasian skin.

    PubMed

    Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

    2014-12-01

    During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. PMID:25084315

  7. Assessment of permeation of lipoproteins in human carotid tissue

    NASA Astrophysics Data System (ADS)

    Ghosn, Mohamad G.; Syed, Saba H.; Leba, Michael; Morrisett, Joel D.; Tuchin, Valery V.; Larin, Kirill V.

    2010-02-01

    Cardiovascular disease is among the leading causes of death in the United States. Specifically, atherosclerosis is an increasingly devastating contributor to the tally and has been found to be a byproduct of arterial permeability irregularities in regards to lipoprotein penetration. To further explore arterial physiology and molecular transport, the imaging technique of Optical Coherence Tomography (OCT) was employed. With OCT, the permeation of glucose (MW = 180 Da), low density lipoprotein (LDL; MW = 2.1 × 106 Da), and high density lipoprotein (HDL; MW = 2.5 × 105 Da) in human carotid tissue was studied to determine the effect of different molecular characteristics on permeation in atherosclerotic tissues. The permeability rates calculated from the diffusion of the molecular agents into the abnormal carotid tissue samples is compared to those of normal, healthy tissue. The results show that in the abnormal tissue, the permeation of agents correlate to the size constraints. The larger molecules of LDL diffuse the slowest, while the smallest molecules of glucose diffuse the fastest. However, in normal tissue, LDL permeates at a faster rate than the other two agents, implying the existence of a transport mechanism that facilitates the passage of LDL molecules. These results highlight the capability of OCT as a sensitive and specific imaging technique as well as provide significant information to the understanding of atherosclerosis and its effect on tissue properties.

  8. Low helium permeation cells for atomic microsystems technology.

    PubMed

    Dellis, Argyrios T; Shah, Vishal; Donley, Elizabeth A; Knappe, Svenja; Kitching, John

    2016-06-15

    Laser spectroscopy of atoms confined in vapor cells can be strongly affected by the presence of background gases. A significant source of vacuum contamination is the permeation of gases such as helium (He) through the walls of the cell. Aluminosilicate glass (ASG) is a material with a helium permeation rate that is many orders of magnitude lower than borosilicate glass, which is commonly used for cell fabrication. We have identified a suitable source of ASG that is fabricated in wafer form and can be anodically bonded to silicon. We have fabricated chip-scale alkali vapor cells using this glass for the windows and we have measured the helium permeation rate using the pressure shift of the hyperfine clock transition. We demonstrate micro fabricated cells with He permeation rates at least three orders of magnitude lower than that of cells made with borosilicate glass at room temperature. Such cells may be useful in compact vapor-cell atomic clocks and as a micro fabricated platform suitable for the generation of cold atom samples. PMID:27304286

  9. Ion-Induced Defect Permeation of Lipid Membranes

    PubMed Central

    Vorobyov, Igor; Olson, Timothy E.; Kim, Jung H.; Koeppe, Roger E.; Andersen, Olaf S.; Allen, Toby W.

    2014-01-01

    We have explored the mechanisms of uncatalyzed membrane ion permeation using atomistic simulations and electrophysiological recordings. The solubility-diffusion mechanism of membrane charge transport has prevailed since the 1960s, despite inconsistencies in experimental observations and its lack of consideration for the flexible response of lipid bilayers. We show that direct lipid bilayer translocation of alkali metal cations, Cl–, and a charged arginine side chain analog occurs via an ion-induced defect mechanism. Contrary to some previous suggestions, the arginine analog experiences a large free-energy barrier, very similar to those for Na+, K+, and Cl–. Our simulations reveal that membrane perturbations, due to the movement of an ion, are central for explaining the permeation process, leading to both free-energy and diffusion-coefficient profiles that show little dependence on ion chemistry and charge, despite wide-ranging hydration energies and the membrane’s dipole potential. The results yield membrane permeabilities that are in semiquantitative agreement with experiments in terms of both magnitude and selectivity. We conclude that ion-induced defect-mediated permeation may compete with transient pores as the dominant mechanism of uncatalyzed ion permeation, providing new understanding for the actions of a range of membrane-active peptides and proteins. PMID:24507599

  10. Combination strategies to enhance transdermal permeation of zidovudine (AZT).

    PubMed

    Thomas, N S; Panchagnula, R

    2003-12-01

    The objective of this study was to evaluate the effect of simultaneous application of two penetration enhancers of different chemical classes or a chemical penetration enhancer and current application on permeation of zidovudine (AZT) across rat skin. Ex vivo permeation of AZT using combinations of cineole or menthol in vehicle with either oleic acid/linolenic acid or 0.5 mA/cm2 anodal current application for 6 h was studied. Penetration enhancers were significantly different in enhancing the permeability of AZT across rat skin and are in the decreasing order of activity: linolenic acid > menthol > oleic acid > cineole > vehicle. The combination of cineole and oleic acid synergistically enhanced transdermal flux of AZT in addition to reducing lag time. However, this was not observed for combinations of menthol with oleic or linolenic acid. On the other hand, the simultaneous application of current with menthol and cineole significantly increased cumulative amounts of AZT permeating during the course of current application and reduced the lag time but failed to further increase steady state flux of AZT. These results suggest that a combination of two penetration enhancers of different classes or the simultaneous use of iontophoresis and a penetration enhancer may be advantageous to achieve permeation enhancement with low risk of skin damage. PMID:14703969

  11. Hydrogen permeation behavior through F82H at high temperature

    SciTech Connect

    Matsuda, S.; Katayama, K.; Shimozori, M.; Fukada, S.; Ushida, H.; Nishikawa, M.

    2015-03-15

    F82H is a primary candidate of structural material and coolant pipe material in a blanket of a fusion reactor. Understanding tritium permeation behavior through F82H is important. In a normal operation of a fusion reactor, the temperature of F82H will be controlled below 550 C. degrees because it is considered that F82H can be used up to 30,000 hours at 550 C. degrees. However, it is necessary to assume the situation where F82H is heated over 550 C. degrees in a severe accident. In this study, hydrogen permeation behavior through F82H was investigated in the temperature range from 500 to 800 C. degrees. In some cases, water vapor was added in a sample gas to investigate an effect of water vapor on hydrogen permeation. The permeability of hydrogen in the temperature range from 500 to 700 C. degrees agreed well with the permeability reported by E. Serra et al. The degradation of the permeability by water vapor was not observed. After the hydrogen permeation reached in a steady state at 700 C. degrees, the F82H sample was heated to 800 C. degrees. The permeability of hydrogen through F82H sample which was once heated up to 800 C. degrees was lower than that of the original one. (authors)

  12. Development of a plasma driven permeation experiment for TPE

    SciTech Connect

    Buchenauer, Dean; Kolasinski, Robert; Shimada, Masa; Donovan, David; Youchison, Dennis; Merrill, Brad

    2014-04-18

    Experiments on retention of hydrogen isotopes (including tritium) at temperatures less than 800 ?C have been carried out in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory [1,2]. To provide a direct measurement of plasma driven permeation in plasma facing materials at temperatures reaching 1000 ?C, a new TPE membrane holder has been built to hold test specimens (=1 mm in thickness) at high temperature while measuring tritium permeating through the membrane from the plasma facing side. This measurement is accomplished by employing a carrier gas that transports the permeating tritium from the backside of the membrane to ion chambers giving a direct measurement of the plasma driven tritium permeation rate. Isolation of the membrane cooling and sweep gases from TPE’s vacuum chamber has been demonstrated by sealing tests performed up to 1000 ?C of a membrane holder design that provides easy change out of membrane specimens between tests. Simulations of the helium carrier gas which transports tritium to the ion chamber indicate a very small pressure drop (~700 Pa) with good flow uniformity (at 1000 sccm). Thermal transport simulations indicate that temperatures up to 1000 ?C are expected at the highest TPE fluxes.

  13. Transdermal permeation modulation by cyclodextrins: a mechanistic study.

    PubMed

    Williams, A C; Shatri, S R; Barry, B W

    1998-08-01

    The purpose of this study was to investigate permeation modulation by beta- and 2-hydroxypropyl-beta-cyclodextrins (beta-CD and HP-beta-CD, respectively) alone and complexed with penetration enhancers for the test drugs 5-fluorouracil and estradiol through human skin, and to probe the value of the CDs in a barrier cream against toluene exposure. Methods include phase solubility studies, permeation experiments, and thermal analysis of stratum corneum; inclusion complexes were characterized by Karl Fischer titrimetry, infrared spectroscopy, and thermal analysis. Results show that complexes of terpenes or toluene with beta-CD were insoluble, whereas those with HP-beta-CD were soluble. The CDs did not enhance flux of either the polar or lipophilic drugs through skin; estradiol permeation was reduced following membrane pretreatment with either CD. Complexation of the lipophilic terpenes with the CDs reduced enhancer efficacy. When formulated into a barrier ointment both CDs, but particularly beta-CD, retarded toluene permeation through the skin and delayed the onset of maximum flux. It is concluded that the CDs themselves are not penetration enhancers for 5-fluorouracil or estradiol in human skin, and that they may be usefully incorporated into a barrier formulation to reduce percutaneous absorption of toxic materials on occupational exposure. PMID:9742549

  14. Vacuum Permeator Analysis for Extraction of Tritium from DCLL Blankets

    SciTech Connect

    Humrickhouse, Paul Weston; Merrill, Brad Johnson

    2014-11-01

    It is envisioned that tritium will be extracted from DCLL blankets using a vacuum permeator. We derive here an analytical solution for the extraction efficiency of a permeator tube, which is a function of only two dimensionless numbers: one that indicates whether radial transport is limited in the PbLi or in the solid membrane, and another that is the ratio of axial and radial transport times in the PbLi. The permeator efficiency is maximized by decreasing the velocity and tube diameter, and increasing the tube length. This is true regardless of the mass transport correlation used; we review several here and find that they differ little, and the choice of correlation is not a source of significant uncertainty here. The PbLi solubility, on the other hand, is a large source of uncertainty, and we identify upper and lower bounds from the literature data. Under the most optimistic assumptions, we find that a ferritic steel permeator operating at 550 °C will need to be at least an order of magnitude larger in volume than previous conceptual designs using niobium and operating at higher temperatures.

  15. Development of a plasma driven permeation experiment for TPE

    DOE PAGESBeta

    Buchenauer, Dean; Kolasinski, Robert; Shimada, Masa; Donovan, David; Youchison, Dennis; Merrill, Brad

    2014-04-18

    Experiments on retention of hydrogen isotopes (including tritium) at temperatures less than 800 ?C have been carried out in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory [1,2]. To provide a direct measurement of plasma driven permeation in plasma facing materials at temperatures reaching 1000 ?C, a new TPE membrane holder has been built to hold test specimens (=1 mm in thickness) at high temperature while measuring tritium permeating through the membrane from the plasma facing side. This measurement is accomplished by employing a carrier gas that transports the permeating tritium from the backside of the membrane to ionmore » chambers giving a direct measurement of the plasma driven tritium permeation rate. Isolation of the membrane cooling and sweep gases from TPE’s vacuum chamber has been demonstrated by sealing tests performed up to 1000 ?C of a membrane holder design that provides easy change out of membrane specimens between tests. Simulations of the helium carrier gas which transports tritium to the ion chamber indicate a very small pressure drop (~700 Pa) with good flow uniformity (at 1000 sccm). Thermal transport simulations indicate that temperatures up to 1000 ?C are expected at the highest TPE fluxes.« less

  16. PREDICTIVE TEST METHODS: PERMEATION OF POLYMERIC MEMBRANES BY ORGANIC SOLVENTS

    EPA Science Inventory

    As the result of screening elastomeric materials that may be suitable for formulating chemical-protective clothing, a simple test method has been developed that allows the prediction of the permeation of an organic solvent through a polymeric membrane. The test method, based on l...

  17. Permeation of chemicals through glove-box glove materials

    SciTech Connect

    Vahdat, N,; Johnson, J.S.; Neidhardt, A.; Cheng, J.; Weitzman, D.

    1994-06-30

    The resistance of two commercial gloves to 20 chemicals commonly used in glove boxes was studied. The chemicals were inorganic acids/bases/salts, organic acids, alcohols, glycols, halogen compounds, sulfur compounds, and hydrocarbons. The ASTM cell was used to study permeation of volatile organic compounds through protective clothing materials using air, flame ionization detector/gas chromatography; a modified version of the cell was used with isopropanol for the nonvolatile organic compounds. Permeation of inorganic compounds through the elastomers was studied using the ASTM cell with water, conductivity meter. A Teflon cell was used with HF and ammonium hydrofluoride. Results: Hypalon protects against all chemicals except trichloroethylene (TCE) and CCl{sub 4}. Acetic acid and ethanol permeated through neoprene, which also did not protect against TCE and CCl{sub 4}. Sulfuric acid dissolved neoprene in 5 h. Kerosene permeated through neoprene in 5 h. Although neoprene showed good resistance to cutting oil, TCE in cutting oil broke through in 61 min. Neoprene showed good protection against all the other chemicals with no breakthrough before 6 h.

  18. Glove permeation by shale oil and coal tar extract

    SciTech Connect

    Nelson, G.O.; Carlson, G.J.; Buerer, A.L.

    1980-02-14

    The vapor penetration of shale oil and coal tar extract through protective gloves composed of either polyethylene, polyvinyl chloride, vinyl, latex, neoprene, Buna-N, acrylonitrile, natural rubber, or nitrile rubber was tested and measured. We used flame ionization techniques to determine the permeation characteristics of the gloves. Neoprene, Buna-N, acrylonitrile and nitrile gloves offered the best protection against the vapors tested.

  19. Why Hydrophilic Water can Permeate Hydrophobic Interior of Lipid Membranes

    NASA Astrophysics Data System (ADS)

    Qiao, Baofu; Olvera de La Cruz, Monica

    2014-03-01

    Water molecules as well as some small molecules have long been found to be able to diffuse across lipid membranes. Such permeation is of significant biological and biotechnological importance. For instance, the permeation of water across lipid membrane plays a important role in regulating ionic concentrations inside of cells. Such water permeation without the assistance of proteins embedded in membranes has been found to be a energetically unfavorable process. We, for the first time, explicitly depict the driving force for such an energetically unfavorable process. Atomistic molecular dynamics simulations are employed to investigate water diffusion in both liquid-crystalline and ordered gel phases of membranes containing zwitterionic DPPC or anionic DLPS lipid. The membrane conformation is calculated to have a critical role in water permeation, regardless of the type of lipid. The fluctuations in the potential energy are found to have a significant, if not the exclusive, role in the transportation of water across lipid membranes. Our results are also informative for the diffusion of small molecules of CO2, O2 and drug molecules, the absence of diffusion of ions, and the diffusion of water into the hydrophobic pores of carbon nanotubes. The authors acknowledge the support from the Office of the Director of Defense Research and Engineering (DDR & E) under Award No. FA9550-10-1-0167.

  20. Phase Change Permeation Technology For Environmental Control Life Support Systems

    NASA Technical Reports Server (NTRS)

    Wheeler, Raymond M.

    2014-01-01

    Use of a phase change permeation membrane (Dutyion [Trademark]) to passively and selectively mobilize water in microgravity to enable improved water recovery from urine/brine for Environment Control and Life Support Systems (ECLSS) and water delivery to plans for potential use in microgravity.

  1. GAS PERMEATION PROPERTIES OF POLY(LACTIC ACID). (R826733)

    EPA Science Inventory

    Abstract

    The need for the development of polymeric materials based on renewable resources has led to the development of poly(lactic acid) (PLA) which is being produced from a feedstock of corn rather than petroleum. The present study examines the permeation of nitrogen...

  2. Gas phase hydrogen permeation in alpha titanium and carbon steels

    NASA Technical Reports Server (NTRS)

    Johnson, D. L.; Shah, K. K.; Reeves, B. H.; Gadgeel, V. L.

    1980-01-01

    Commercially pure titanium and heats of Armco ingot iron and steels containing from 0.008-1.23 w/oC were annealed or normalized and machined into hollow cylinders. Coefficients of diffusion for alpha-Ti and alpha-Fe were determined by the lag-time technique. Steady state permeation experiments yield first power pressure dependence for alpha-Ti and Sievert's law square root dependence for Armco iron and carbon steels. As in the case of diffusion, permeation data confirm that alpha-titanium is subject to at least partial phase boundary reaction control while the steels are purely diffusion controlled. The permeation rate in steels also decreases as the carbon content increases. As a consequence of Sievert's law, the computed hydrogen solubility decreases as the carbon content increases. This decreases in explained in terms of hydrogen trapping at carbide interfaces. Oxidizing and nitriding the surfaces of alpha-titanium membranes result in a decrease in the permeation rate for such treatment on the gas inlet surfaces but resulted in a slight increase in the rate for such treatment on the gas outlet surfaces. This is explained in terms of a discontinuous TiH2 layer.

  3. Status of Tritium Permeation Barrier Development in the EU

    SciTech Connect

    Konys, J.; Aiello, A.; Benamati, G.; Giancarli, L.

    2005-05-15

    Tritium permeation can be significantly reduced by a suitable barrier on the structural materials of a future fusion power plant. Since alumina has the capability of tritium permeation reduction, the development of such coatings on ferritic martensitic steels by different techniques like hot-dip aluminizing (HDA) by Forschungszentrum Karlsruhe, Germany (FZK) and chemical vapor deposition (CVD) by Commissariat a l'Energie Atomique, France (CEA) was funded by the European Commission (EC) during the last 10 years. The final objective was to identify a so-called reference coating for structural components of a lithium-lead cooled blanket.This paper describes the process specifications and the results of the corresponding hydrogen permeation measurements, performed at ENEA, Brasimone, Italy. The results for CVD and HDA coating showed clearly, that Permeation Reduction Factor's (PRF) of >1000 were sufficiently exceeded in H{sub 2} gas, but much lower values were obtained in the Pb-17Li melt. The post mortem analysis revealed that surface imperfections and spallation of parts of the coatings were responsible for the too low PRF's. Because of shifting of priorities and changes in the blanket design from WCLL to HCLL, the EU funding of all major R and D activities was postponed in 2002 until the redesign of the European Blanket Concepts was finished.

  4. Permeation of Dopamine Sulfate through the Blood-Brain Barrier

    PubMed Central

    Suominen, Tina; Piepponen, T. Petteri; Kostiainen, Risto

    2015-01-01

    Dopamine sulfate (DA-3- and DA-4-S) have been determined in the human brain, but it is unclear whether they are locally formed in the central nervous system (CNS), or transported into the CNS from peripheral sources. In the current study, permeation of the blood-brain barrier (BBB) by DA-S was studied by injecting 13C6-labelled regioisomers of DA-S (13DA-3-S and 13DA-4-S) and dopamine (DA) subcutaneously (s.c.) in anesthetized rats, then analyzing brain microdialysis and plasma samples by UPLC-MS/MS. The results in the microdialysis samples demonstrated that brain concentrations of 13DA-S regioisomers clearly increased after the s.c. injections. The concentration of DA did not change, indicating the permeation of DA-S through an intact BBB. The analysis of plasma samples, however, showed that DA-S only permeates the BBB to a small extent, as the concentrations in plasma were substantially higher than in the microdialysis samples. The results also showed that the concentrations of DA-3-S were around three times higher than the concentrations of DA-4-S in rat brain, as well as in the plasma samples after the s.c. injections, indicating that DA-3-S and DA-4-S permeate the BBB with similar efficiency. The fate of 13DA-S in brain was followed by monitoring 13C6-labelled DA-S hydrolysis products, i.e. 13DA and its common metabolites; however, no 13C6-labelled products were detected. This suggests that DA-S either permeates through the BBB back to the peripheral circulation or is dissociated or metabolized by unexpected mechanisms. PMID:26207745

  5. Comparative Study of Permeatal Sandwich Tympanoplasty and Postaural Underlay Technique

    PubMed Central

    Nagpure, Prakash Shankarrao; Yadav, Manish; Chavan, Sushil

    2016-01-01

    Introduction Tympanoplasty is the most common operation performed by an Otolaryngologist right from the period of residency. During the last hundred years various modifications in this surgical technique have come up because of continued efforts made by otologists all over the world to achieve the best surgical outcome. Aim To compare the graft take up and complications associated with the Permeatal Sandwich Tympanoplasty performed with the use of Otoendoscope and traditional Postaural Underlay technique of Tympanoplasty from 1st September 2014 to 30th August 2015. Materials and Methods Patients attending the ENT OPD, suffering from Chronic Suppurative Otitis Media (CSOM) were selected on the basis of type of perforation and their workup was done to assess the candidature for tympanoplasty. Results A total of 100 patients were included in the study and the overall graft take was 92.3% in cases of Permeatal Sandwich technique as compared to 64.58% in the case of postaural underlay technique, with a majority of the failures in the large central perforation group rendering a p = 0.021 for patients operated for Large perforations, p = 0.036 for moderate perforations and p = 0.476 for small perforations. The overall p = 0.000649 which is highly significant. On comparing the complications there were only 2 cases in Permeatal Sandwich Technique compared to 25 cases in Postaural Underlay technique rendering a highly significant p-value 0f 0.000000348. There was a difference in hearing improvement with majority of the cases improving to the range of 16-25 dB in Permeatal Sandwich technique compared to 26-45 dB in Postaural Underlay technique. Conclusion Permeatal Sandwich technique produce much better results when compared with Postaural approach in terms of graft take up, complications and hearing improvement. PMID:27190842

  6. Simulation of controllable permeation in PNIPAAm coated membranes

    NASA Astrophysics Data System (ADS)

    Ehrenhofer, Adrian; Wallmersperger, Thomas; Richter, Andreas

    2016-04-01

    Membranes separate fluid compartments and can comprise transport structures for selective permeation. In biology, channel proteins are specialized in their atomic structure to allow transport of specific compounds (selectivity). Conformational changes in protein structure allow the control of the permeation abilities by outer stimuli (gating). In polymeric membranes, the selectivity is due to electrostatic or size-exclusion. It can thus be controlled by size variation or electric charges. Controllable permeation can be useful to determine particle-size distributions in continuous flow, e.g. in microfluidics and biomedicine to gain cell diameter profiles in blood. The present approach uses patterned polyethylene terephthalate (PET) membranes with hydrogel surface coating for permeation control by size-exclusion. The thermosensitive hydrogel poly(N-isopropylacrylamide) (PNIPAAm) is structured with a cross-shaped pore geometry. A change in the temperature of the water flow through the membrane leads to a pore shape variation. The temperature dependent behavior of PNIPAAm can be numerically modeled with a temperature expansion model, where the swelling and deswelling is depicted by temperature dependent expansion coefficients. In the present study, the free swelling behavior was implemented to the Finite Element tool ABAQUS for the complex composite structure of the permeation control membrane. Experimental values of the geometry characteristics were derived from microscopy images with the tool Image J and compared to simulation results. Numerical simulations using the derived thermo-mechanical model for different pore geometries (circular, rectangle, cross and triangle) were performed. With this study, we show that the temperature expansion model with values from the free swelling behavior can be used to adequately predict the deformation behavior of the complex membrane system. The predictions can be used to optimize the behavior of the membrane pores and the overall

  7. Towards a unified model of passive drug permeation I: origins of the unstirred water layer with applications to ionic permeation.

    PubMed

    Ghosh, Avijit; Scott, Dennis O; Maurer, Tristan S

    2014-02-14

    In this work, we provide a unified theoretical framework describing how drug molecules can permeate across membranes in neutral and ionized forms for unstirred in vitro systems. The analysis provides a self-consistent basis for the origin of the unstirred water layer (UWL) within the Nernst-Planck framework in the fully unstirred limit and further provides an accounting mechanism based simply on the bulk aqueous solvent diffusion constant of the drug molecule. Our framework makes no new assumptions about the underlying physics of molecular permeation. We hold simply that Nernst-Planck is a reasonable approximation at low concentrations and all physical systems must conserve mass. The applicability of the derived framework has been examined both with respect to the effect of stirring and externally applied voltages to measured permeability. The analysis contains data for 9 compounds extracted from the literature representing a range of permeabilities and aqueous diffusion coefficients. Applicability with respect to ionized permeation is examined using literature data for the permanently charged cation, crystal violet, providing a basis for the underlying mechanism for ionized drug permeation for this molecule as being due to mobile counter-current flow. PMID:24211511

  8. ENHANCED PERVAPORATION SEPARATION EFFICIENCY VIA STAGED FRACTIONAL CONDENSATION (DEPHLEGMATION) OF PERMEATE VAPOR

    EPA Science Inventory

    In traditional pervaporation systems, the permeate vapor is completely condensed to obtain a liquid permeate stream. For example, in the recovery of ethanol from a 5-wt% aqueous stream (such as a biomass fermentation broth), the permeate from a silicone rubber pervaporation membr...

  9. REFINEMENT OF A MODEL TO PREDICT THE PERMEATION OF PROTECTIVE CLOTHING MATERIALS

    EPA Science Inventory

    A prototype of a predictive model for estimating chemical permeation through protective clothing materials was refined and tested. he model applies Fickian diffusion theory and predicts permeation rates and cumulative permeation as a function of time for five materials: butyl rub...

  10. MICROSTRUCTURAL EXAMINATION AND DEUTERIUM PERMEATION TESTING OF ADVANCED COATINGS FOR TRITIUM SERVICE

    SciTech Connect

    Korinko, P.

    2004-01-24

    A plant directed research and development task to develop and study new, improved, and low cost tritium permeation barriers was initiated in FY02. The project was intended to determine the permeation rate and permeation reduction factor of substrate materials and coated materials. The samples were characterized for microstructural and microchemical consistency. Permeation tests were also run. The sample geometry and sample sealing method selected for the coatings posed significant schedule and technical challenges. Diffusivity were consistent with published values but permeation data exhibited an unexpected sample to sample variation. The effort has lead to an improved sample design that will be used to support a Process Development task.

  11. Water permeation drives tumor cell migration in confined microenvironments.

    PubMed

    Stroka, Kimberly M; Jiang, Hongyuan; Chen, Shih-Hsun; Tong, Ziqiu; Wirtz, Denis; Sun, Sean X; Konstantopoulos, Konstantinos

    2014-04-24

    Cell migration is a critical process for diverse (patho)physiological phenomena. Intriguingly, cell migration through physically confined spaces can persist even when typical hallmarks of 2D planar migration, such as actin polymerization and myosin II-mediated contractility, are inhibited. Here, we present an integrated experimental and theoretical approach ("Osmotic Engine Model") and demonstrate that directed water permeation is a major mechanism of cell migration in confined microenvironments. Using microfluidic and imaging techniques along with mathematical modeling, we show that tumor cells confined in a narrow channel establish a polarized distribution of Na+/H+ pumps and aquaporins in the cell membrane, which creates a net inflow of water and ions at the cell leading edge and a net outflow of water and ions at the trailing edge, leading to net cell displacement. Collectively, this study presents an alternate mechanism of cell migration in confinement that depends on cell-volume regulation via water permeation. PMID:24726433

  12. Resin Permeation Through Compressed Glass Insulation for Iter Central Solenoid

    NASA Astrophysics Data System (ADS)

    Reed, R.; Roundy, F.; Martovetsky, N.; Miller, J.; Mann, T.

    2010-04-01

    Concern has been expressed about the ability of the resin system to penetrate the compressed dry glass of the turn and layer insulation during vacuum-pressure impregnation of ITER Central Solenoid (CS) modules. The stacked pancake layers of each module result in compression loads up to 9×104 kg (100 tons) on the lowest layers of each segment. The objective of this program was to assess the effects of this compressive load on resin permeation under resin-transfer conditions and with materials identical to that expected to be used in actual coil fabrication [45-50 °C, vacuum of 133 Pa (1 torr), DGEBF/anhydride epoxy resin system, E-glass satin weave, applied pressure of 125 kPa]. The experimental conditions and materials are detailed and the permeation results presented in this paper.

  13. In vitro permeation of levothyroxine across the skin.

    PubMed

    Padula, Cristina; Pappani, Alice; Santi, Patrizia

    2008-02-12

    The aim of this work was to investigate the in vitro transdermal permeation characteristics of sodium levothyroxine, in view of its topical application. Permeation experiments were performed in vitro, using rabbit ear skin as barrier. At the end of the experiments levothyroxine retained in the skin was extracted and quantified by HPLC. The formulations tested were solutions and a commercial cream. The use of dimethyl beta-cyclodextrin as solubilizing agent increased to a significant extent levothyroxine solubility, but reduced its skin accumulation. Skin stripping before drug application produced a considerable increase in the amount retained and levothyroxine was found also in the receptor compartment. The application of the commercial cream in occlusive conditions increased to a significant extent drug retention in the skin. In conclusion, levothyroxine skin administration is promising in view of a localized effect, because it was retained in the skin. On the contrary, transdermal administration in view of systemic effect does not represent a concrete possibility. PMID:17931806

  14. High-sensitivity permeation measurements on flexible OLED substrates

    NASA Astrophysics Data System (ADS)

    Paetzold, Ralph; Henseler, Debora; Heuser, Karsten; Cesari, Valentina; Sarfert, Wiebke; Wittmann, Georg; Winnacker, Albrecht

    2004-02-01

    We describe a novel method to measure permeation rates for oxidizing agents with very high sensitivity. The technique is based on monitoring the resistance of a degrading Ca sensor in situ, inside a climate chamber. A sensitivity limit below 10-6 g/m2 day is reported for accelerated measurement conditions of 38°C and 90% relative humidity. The benefits of the method are demonstrated for single- and double-sided barrier foils, and the temperature and humidity dependence of the transport through PET is analyzed in detail. The method is also applied to obtain permeation rates for a barrier-coated substrate after as well as during bending. Theoretical simulations are used to evaluate the influence of a defect-dominated transport mechanism on the experimental results and to model the time evolution of the concentration profile in a double-barrier stack. Implications for the development of barrier-enhanced substrates for flexible OLED applications are discussed.

  15. Water Permeation Drives Tumor Cell Migration in Confined Microenvironments

    PubMed Central

    Stroka, Kimberly M.; Jiang, Hongyuan; Chen, Shih-Hsun; Tong, Ziqiu; Wirtz, Denis; Sun, Sean X.; Konstantopoulos, Konstantinos

    2014-01-01

    SUMMARY Cell migration is a critical process for diverse (patho) physiological phenomena. Intriguingly, cell migration through physically confined spaces can persist even when typical hallmarks of 2D planar migration, such as actin polymerization and myosin II-mediated contractility, are inhibited. Here, we present an integrated experimental and theoretical approach (“Osmotic Engine Model”) and demonstrate that directed water permeation is a major mechanism of cell migration in confined microenvironments. Using microfluidic and imaging techniques along with mathematical modeling, we show that tumor cells confined in a narrow channel establish a polarized distribution of Na+/H+ pumps and aquaporins in the cell membrane, which creates a net inflow of water and ions at the cell leading edge and a net outflow of water and ions at the trailing edge, leading to net cell displacement. Collectively, this study presents an alternate mechanism of cell migration in confinement that depends on cell-volume regulation via water permeation. PMID:24726433

  16. Assessment of permeation quality of concrete through mercury intrusion porosimetry

    SciTech Connect

    Kumar, Rakesh; Bhattacharjee, B

    2004-02-01

    Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated.

  17. Tritium percolation, convection, and permeation in fusion solid breeder blankets

    SciTech Connect

    Billone, M.C.; Liu, Y.Y.

    1985-01-01

    Models are developed to describe the percolation of released tritium through the breeder interconnected porosity to the purge stream, convection of tritium by the helium purge stream, and leakage or permeation of tritium through the structural material to the primary coolant system. Important parameters in the models are tritium generation rate, breeder microstructure, tritium species in the gas phase, temperatures, tritium diffusivities and permeabilities, and effectiveness of oxide barriers.

  18. Percutaneous permeation measurement of topical phthalocyanine by photoacoustic technique

    NASA Astrophysics Data System (ADS)

    Silva, Emanoel P. O.; Barja, Paulo R.; Cardoso, Luiz E.; Beltrame, Milton

    2012-11-01

    This investigation have studied photoacoustic (PA) technique to percutaneous permeation of topical hydroxy-(29H,31H-phthalocyaninate) aluminum (PcAlOH) on pig ear skin. The PcAlOH was incorporated in an emulsion (O/W) (1 mg/dl) with assessed stability parameters of: pH, short and long term stability tests (in the several conditions). The skin was prepared through a heat separation technique, and with a scalpel, the outer skin of the cartilage was removed. The skins were then cut into 4 cm2 pieces and treated with sodium bromide 2 mol/L for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics was determined by photoacoustic technique in an open photoacoustic cell. Short (after preparation) and long-term stability tests showed no phase separation. The emulsion developed pH 7.6 and after incorporating the pH was unchanged. The typical times for percutaneous permeation of the emulsion base and emulsion + PcAlOH were 182 (±6) and 438 (±3) s, respectively. This study indicated that the formulations containing PcAlOH have stabile characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the greater absorption time than observed in the base formulation. The used photoacoustic technical to examine the penetration kinetics of PcAlOH in pig ear skin was adequate and may be employed in the determination of the percutaneous permeation of phthalocyanines.

  19. Percutaneous Permeation of Topical Phtalocyanine Studied by Photoacoustic Measurements

    NASA Astrophysics Data System (ADS)

    Silva, E. P. O.; Beltrame, M.; Cardoso, L. E.; Barja, P. R.

    2012-11-01

    The purpose of this study was to evaluate the percutaneous permeation of topical hydroxy-(29 H,31 H-phthalocyaninato)aluminum (PcAlOH) on pig ear skin employing photoacoustic (PA) measurements. The PcAlOH was incorporated in an emulsion with assessed stability parameters of pH and short- and long-term stability tests. Pig skin was prepared through a heat separation technique, and the outer skin of the cartilage was removed with a scalpel. Skin samples were then cut and treated with sodium bromide 2 mol . L-1 for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics were determined by PA measurements as a function of time, performed with an open PA cell developed at Universidade do Vale do Paraíba. Short- and long-term stability tests showed no phase separation. A significant difference was found between the typical times for percutaneous permeation of the emulsion base and the emulsion + PcAlOH. The study showed two absorption transients due to the physical diffusion of molecules in the skin sample. The first is attributed to the penetration of molecules that promptly passed through the lipid barrier, while the second is related to the molecules that had greater difficulty of passing through. This slower component in the absorption curves is attributed to the penetration of PcAlOH, a planar molecule whose percutaneous penetration is more difficult. The study indicates that the formulations containing PcAlOH have stable characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the larger time constant observed. PA measurements allowed the evaluation of the penetration kinetics of PcAlOH in pig ear skin; the methodology employed may be used in the determination of the percutaneous permeation of phthalocyanines in further studies.

  20. Electrostatic Tuning of Permeation and Selectivity in Aquaporin Water Channels

    PubMed Central

    Jensen, Morten Ø.; Tajkhorshid, Emad; Schulten, Klaus

    2003-01-01

    Water permeation and electrostatic interactions between water and channel are investigated in the Escherichia coli glycerol uptake facilitator GlpF, a member of the aquaporin water channel family, by molecular dynamics simulations. A tetrameric model of the channel embedded in a 16:0/18:1c9-palmitoyloleylphosphatidylethanolamine membrane was used for the simulations. During the simulations, water molecules pass through the channel in single file. The movement of the single file water molecules through the channel is concerted, and we show that it can be described by a continuous-time random-walk model. The integrity of the single file remains intact during the permeation, indicating that a disrupted water chain is unlikely to be the mechanism of proton exclusion in aquaporins. Specific hydrogen bonds between permeating water and protein at the channel center (at two conserved Asp-Pro-Ala “NPA” motifs), together with the protein electrostatic fields enforce a bipolar water configuration inside the channel with dipole inversion at the NPA motifs. At the NPA motifs water-protein electrostatic interactions facilitate this inversion. Furthermore, water-water electrostatic interactions are in all regions inside the channel stronger than water-protein interactions, except near a conserved, positively charged Arg residue. We find that variations of the protein electrostatic field through the channel, owing to preserved structural features, completely explain the bipolar orientation of water. This orientation persists despite water translocation in single file and blocks proton transport. Furthermore, we find that for permeation of a cation, ion-protein electrostatic interactions are more unfavorable at the conserved NPA motifs than at the conserved Arg, suggesting that the major barrier against proton transport in aquaporins is faced at the NPA motifs. PMID:14581193

  1. Free energy calculation of permeation through aquaporin-5

    NASA Astrophysics Data System (ADS)

    Bastien, David

    The work of this paper continues upon the large area of research being done on aquaporins (AQPs). AQPs are proteins that take on the role of facilitating the transfer of substances, mainly water, across cell membranes. There are many different types of AQPs, with each of these highly selective proteins conducting only certain solutes, along with unique permeability rates. The permeation characteristics of aquaporins rely mostly on the residue hydrophobicity and steric restraints of the aromatic arginine (ar/R) region of the protein channel. The purpose of this paper is to analyze the structures of aquaporin-5 (AQP5) and aquaglycerolporin (Glpf), including a radius profile of the respective protein channels, and to compare them to permeation events using steered molecular dynamics (SMD) pulling simulations. Two in silico experiments are performed in order to achieve the free Energy landscape of a single water molecule permeating through the four channels of both Aqp5 and GlpF. The equilibrium free energy curves are calculated from the non-equilibrium, irreversible work measurements using the fluctuation-dissipation theorem (FDT) of Brownian dynamicis (BD). The free energy profiles are then compared and related to the structural profiles of AQP5 and GlpF. The change in free energy across the ar/R region in AQP5 is found to be reasonably larger than that of GlpF. The free energy profiles of AQP5 and GlpF agree with the diameter profile of the channels respectively. Furthermore, free energy calculations are computed for the permeation of Na+ and Cl- ions through the central pore of Aqp5, which provide some insight into the structural mechanisms of AQP5. The free energy barrier for ion transport through the central pore is found to be very large, peaking at around 11 Kcal/mol for chloride and 20 Kcal/mol for sodium.

  2. Electrostatic tuning of permeation and selectivity in aquaporin water channels.

    PubMed

    Jensen, Morten Ø; Tajkhorshid, Emad; Schulten, Klaus

    2003-11-01

    Water permeation and electrostatic interactions between water and channel are investigated in the Escherichia coli glycerol uptake facilitator GlpF, a member of the aquaporin water channel family, by molecular dynamics simulations. A tetrameric model of the channel embedded in a 16:0/18:1c9-palmitoyloleylphosphatidylethanolamine membrane was used for the simulations. During the simulations, water molecules pass through the channel in single file. The movement of the single file water molecules through the channel is concerted, and we show that it can be described by a continuous-time random-walk model. The integrity of the single file remains intact during the permeation, indicating that a disrupted water chain is unlikely to be the mechanism of proton exclusion in aquaporins. Specific hydrogen bonds between permeating water and protein at the channel center (at two conserved Asp-Pro-Ala "NPA" motifs), together with the protein electrostatic fields enforce a bipolar water configuration inside the channel with dipole inversion at the NPA motifs. At the NPA motifs water-protein electrostatic interactions facilitate this inversion. Furthermore, water-water electrostatic interactions are in all regions inside the channel stronger than water-protein interactions, except near a conserved, positively charged Arg residue. We find that variations of the protein electrostatic field through the channel, owing to preserved structural features, completely explain the bipolar orientation of water. This orientation persists despite water translocation in single file and blocks proton transport. Furthermore, we find that for permeation of a cation, ion-protein electrostatic interactions are more unfavorable at the conserved NPA motifs than at the conserved Arg, suggesting that the major barrier against proton transport in aquaporins is faced at the NPA motifs. PMID:14581193

  3. Permeation and destructive effects of disinfectants on protective gloves.

    PubMed

    Mellström, G A; Lindberg, M; Boman, A

    1992-03-01

    In working situations where there is a possibility of acquiring blood-borne infections, the use of disinfectants is important. It is also important to use protective gloves, both to protect the skin against disinfectants and to protect against infections. Changes in the structure of the glove material may, however, interfere with the protective capability of the gloves. The influence of 4 disinfectants on the material structure and protective effect of 6 different brands of protective gloves was studied. The proposed International Organization for Standardization (ISO) standard method for determining the liquid chemical resistance of air-impermeable materials was used for permeation testing. Pieces of latex and vinyl glove were also exposed to isopropanol and ethanol for 10, 30 and 60 min and then viewed in a scanning electron microscope. Isopropanol permeated through latex and vinyl gloves in less than 10 min. The polyethylene (PE) gloves were of quite variable quality, and the breakthrough time ranged from 4 to greater than 240 min. The latex and vinyl gloves were also permeated by ethanol, but at a much lower rate. The disinfectants Blifacid, based on p-chloro-m-cresol, and Cidex, based on glutaraldehyde, did not permeate any of the gloves tested within 60 min. Isopropanol had a destructive effect on the material, which became opaque, stiff and brittle. This change in structure was verified with the scanning electron microscope. The tested gloves of latex, vinyl and PE, gave acceptable protection from contact with Blifacid and Cidex for at least 60 min. The same gloves do not give any total protection from contact with isopropanol and ethanol. PMID:1505181

  4. Silicon oxide permeation barrier coating of PET bottles and foils

    NASA Astrophysics Data System (ADS)

    Steves, Simon; Deilmann, Michael; Awakowicz, Peter

    2009-10-01

    Modern packaging materials such as polyethylene terephthalate (PET) have displaced established materials in many areas of food and beverage packaging. Plastic packing materials offer are various advantages concerning production and handling. PET bottles for instance are non-breakable and lightweight compared to glass and metal containers. However, PET offers poor barrier properties against gas permeation. Therefore, the shelf live of packaged food is reduced. Permeation of gases can be reduced by depositing transparent plasma polymerized silicon oxide (SiOx) barrier coatings. A microwave (2.45 GHz) driven low pressure plasma reactor is developed based on a modified Plasmaline antenna to treat PET foils or bottles. To increase the barrier properties of the coatings furthermore a RF substrate bias (13.56 MHz) is applied. The composition of the coatings is analyzed by means of Fourier transform infrared (FTIR) spectroscopy regarding carbon and hydrogen content. Influence of gas phase composition and substrate bias on chemical composition of the coatings is discussed. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become quartz-like. Regarding oxygen permeation a barrier improvement factor (BIF) of 70 is achieved.

  5. In vitro experiment optimization for measuring tetrahydrocannabinol skin permeation.

    PubMed

    Challapalli, Prasad V N; Stinchcomb, Audra L

    2002-07-25

    The purpose of this study was to optimize in vitro experimental conditions for the measurement of Delta(9)-tetrahydrocannabinol (Delta(9)-THC) permeation across human skin using a flow-through diffusion cell system. The drug permeation rates through intact and stripped (stratum corneum (SC) removed) skin were also compared in order to determine if the SC provided significant resistance to the diffusion of hydrophobic Delta(9)-THC. The receiver fluids evaluated were HEPES-buffered Hank's balanced salt solution (HHBSS) with either 4 or 6% bovine serum albumin (BSA), Polyoxyethylene 20 Oleyl Ether (Brij 98) solution (0.5 and 6.0%), and hydroxypropyl-beta-cyclodextrin (HPBCD). The Delta(9)-THC permeability was significantly higher into Brij 98 solutions than into 4% BSA. BSA 6% receiver solutions showed significantly higher Delta(9)-THC permeation over BSA 4%. There were no significant differences in Delta(9)-THC permeability or lag time values between 0.5 and 6% Brij 98 receiver solutions. HPBCD failed to work as a suitable receiver solution. The Delta(9)-THC flux in the stripped skin experiments exceeded the flux in the intact skin experiments. It appears that the SC provides some resistance to the diffusion of Delta(9)-THC across human skin. These experimental results have confirmed the utility of several receiver solutions for the in vitro human skin diffusion study of Delta(9)-THC. PMID:12100860

  6. Helium permeation through a silicalite-1 tubular membrane

    NASA Astrophysics Data System (ADS)

    Hernández, M. G.; Salinas-Rodríguez, E.; Gómez, S. A.; Roa-Neri, J. A. E.; Alfaro, S.; Valdés-Parada, F. J.

    2015-06-01

    A silicalite-1 tubular membrane was prepared on the inner surface of a porous α-alumina support. Helium permeation at different feed volumetric flows (11-41 mL/min) with different sweep flow rates (9-90 mL/min) at STP conditions was measured. The molar fraction was obtained as a function of the residence time ratio. The influences of the geometric parameters of the tubular system and the feed flow rates on the permeation through the membrane were investigated. The dependence of the permeances with the residence time ratio was experimentally obtained and we propose that this dependence is a useful design criterion for tubular membrane permeation systems. The best results in this work were obtained for Q He, in / Q N2, in = 0.22 for V SS / V TS = 7.3. Also, the data showed that an appropriate combination of the flows and the area sections of the system resulted in an optimum value for the Péclet number of 0.3. The experimental data were reproduced by numerically solving the Maxwell-Stefan equations under the assumption that transport across the membrane can be modeled in terms of a Robin-type boundary condition.

  7. Electrochemical study of hydrogen permeation through tungsten near room temperature

    NASA Astrophysics Data System (ADS)

    Manhard, A.; Kapser, S.; Gao, L.

    2015-08-01

    We used an electrochemical double cell to study permeation of hydrogen through a 3.5 μm thick sputter-deposited tungsten layer on a 25 μm thick palladium support. The temperature dependence of the steady-state permeation current was studied in the range from 266 to 333 K for a constant charging potential on the entry side and zero hydrogen concentration on the exit side of the sample foil. We found that the data is best described by a sum of two Arrhenius terms. We postulate that the higher activation energy of 0.86 ± 0.07 eV corresponds to permeation through bulk grains and may approach the literature value of 1.43 ± 0.26 eV for even higher temperature. For the second, lower activation energy of 0.39 ± 0.03 eV, we currently consider fast diffusion along grain boundaries the most likely explanation.

  8. Selective permeation of hydrogen gas using cellulose nanofibril film.

    PubMed

    Fukuzumi, Hayaka; Fujisawa, Shuji; Saito, Tsuguyuki; Isogai, Akira

    2013-05-13

    Biobased membranes that can selectively permeate hydrogen gas have been developed from aqueous dispersions of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCN) prepared from wood cellulose: TOCN-coated plastic films and self-standing TOCN films. Compared with TOCNs with sodium, lithium, potassium, and cesium carboxylate groups, TOCN with free carboxyl groups (TOCN-COOH) had much high and selective H2 gas permeation performance. Because permeabilities of H2, N2, O2, and CO2 gases through the membranes primarily depended on their kinetic diameters, the gas permeation behavior of the various TOCNs can be explained in terms of a diffusion mechanism. Thus, the selective H2 gas permeability for TOCN-COOH was probably due to a larger average size in free volume holes present between nanofibrils in the layer and film than those of other TOCNs with metal carboxylate groups. The obtained results indicate that TOCN-COOH membranes are applicable as biobased H2 gas separation membranes in fuel cell electric power generation systems. PMID:23594396

  9. Drug silica nanocomposite: preparation, characterization and skin permeation studies.

    PubMed

    Pilloni, Martina; Ennas, Guido; Casu, Mariano; Fadda, Anna Maria; Frongia, Francesca; Marongiu, Francesca; Sanna, Roberta; Scano, Alessandra; Valenti, Donatella; Sinico, Chiara

    2013-01-01

    The aim of this work was to evaluate silica nanocomposites as topical drug delivery systems for the model drug, caffeine. Preparation, characterization, and skin permeation properties of caffeine-silica nanocomposites are described. Caffeine was loaded into the nanocomposites by grinding the drug with mesoporous silica in a ball mill up to 10 h and the efficiency of the process was studied by XRPD. Formulations were characterized by several methods that include FTIR, XRPD, SEM and TEM. The successful loading of caffeine was demonstrated by XRPD and FTIR. Morphology was studied by SEM that showed particle size reduction while TEM demonstrated formation of both core-shell and multilayered caffeine-silica structures. Solid-state NMR spectra excluded chemical interactions between caffeine and silica matrix, thus confirming that no solid state reactions occurred during the grinding process. Influence of drug inclusion in silica nanocomposite on the in vitro caffeine diffusion into and through the skin was investigated in comparison with a caffeine gel formulation (reference), using newborn pig skin and vertical Franz diffusion cells. Results from the in vitro skin permeation experiments showed that inclusion into the nanocomposite reduced and delayed caffeine permeation from the silica nanocomposite in comparison with the reference, independently from the amount of the tested formulation. PMID:22324371

  10. Release and skin permeation studies of Naproxen from hydrophillic gels and effect of terpenes as enhancers on its skin permeation.

    PubMed

    Ray, S; Ghosal, S K

    2003-04-01

    The skin permeation parameters of Naproxen through albino mouse abdominal skin was investigated. Out of 5 formulations those prepared from carbomer gels showed promising results and were chosen for investigating enhancing effect of various terpene alcohol viz. Geraniol and Nerolidol and cyclic terpenes viz menthol and thymol on skin permeation of Naproxen. Out of the four terpenes studied Geraniol exhibited the highest enhancing effect with enhancement ratio 4.6, while Nerolidol had an enhancement ratio 4.2. The cyclic terpenes had less prompt enhancing effect compared to the alcohol terpenes, out of the two, methol showed the largest effect with an enhancement ratio of about 3.7 and thymol had an enhancement ratio of 3.5. PMID:12806832

  11. Permeation measurement and barrier films for flexible display applications

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodong

    A new technique was developed to detect very low gas permeation rates associated with ultra-barrier coatings for flexible display applications. The permeation rate detection limit was improved over conventional methods based on detecting accumulated permeant in a closed, evacuated volume downstream from the sample of interest. This process uses a mass spectrometer as the permeant detector, and involves programmed accumulation, detection, and evacuation of the permeant species through controlled movement of valves and thus has been termed Programmed Valving Mass Spectrometry (PVMS). The PVMS system sensitivity was calibrated at room temperature for different permeant species including water vapor and oxygen. The calibrated lower detection limit for water vapor permeation meets the ultra-barrier requirement. However, the calibrated lower detection limit for oxygen does not meet such a requirement, which is due to a significant systematic error during oxygen detection. The calibration factors for permeation of reactive/condensable species with different chemical reactivities (CO2, N2, water vapor, and O2) were compared with their relative effusion rates through a flow orifice measured by the PVMS system. Both results appeared to be correlated with the chemical reactivities of the gases, and indicated a strong chemical influence on the lowest gas detection limit in the PVMS system. Based on a qualitative analysis, the significant error for oxygen detection was further ascribed to the chemical reaction of oxygen with carbon impurities near the hot filament of the mass spectrometer. Research on permeation barrier films deposited on polymer substrate was carried out using plasma enhanced chemical vapor deposition (PECVD). Attempts to use PECVD hexamethyldisiloxane (HMDSO) precursors to form oxide films were unsuccessful due to the films' highly porous microstructure. This is believed to be due to gas phase reactions between the HMDSO precursor and the oxygen carrier gas

  12. Simultaneous permeation of tamoxifen and gamma linolenic acid across excised human skin. Further evidence of the permeation of solvated complexes.

    PubMed

    Karia, Clare; Harwood, John L; Morris, Andy P; Heard, Charles M

    2004-03-01

    Tamoxifen is the hormonal treatment of choice in women who have hormone-dependent breast cancer and its efficacy in those women considered to have a high risk of developing breast cancer, has also been established. Gamma linolenic acid (GLA) has been shown to decrease the invasion of breast cancer and recent studies have demonstrated that GLA can enhance the oestrogen receptor down-regulation induced by tamoxifen. However, tamoxifen is associated with serious side-effects due mainly to systemic delivery, and targeted delivery of both tamoxifen and GLA would be highly beneficial. This work was a preliminary study for the development of a transcutaneous system to simultaneously deliver both tamoxifen and GLA directly to the breast. Full thickness human skin was dosed with 500 microl saturated solution of tamoxifen in borage oil (25% GLA) and the simultaneous permeation of the two actives determined. There was rapid flux with minimal lag time, the cumulative permeation at 24 h was 764.3 +/- 94.2 microg cm(-2) for GLA and 5.44 +/- 0.67 microg cm(-2) for tamoxifen: the latter being comparable to the amount of tamoxifen associated with cancerous breast tissue from a 20 mg oral dose. The ratio of GLA/tamoxifen permeated at different timepoints was quite consistent, both in terms of mass (mean 138, S.D. 15.1) and mols (mean 184, S.D. 20.3). It was determined that 2.5 molecules of GLA were associated with each molecule of tamoxifen in the permeation process, equating to a solvation cage of three molecules of triacylglycerol. This study has demonstrated the feasibility of administering simultaneously tamoxifen and GLA using borage oil as vehicle, which warrants further investigation as a novel topical two-component system in relation to or prophylaxis of those perceived at high risk of developing breast cancer. The study also provides further evidence of the permeation of solvated complexes across skin, rather than discrete penetrant molecules. PMID:15129999

  13. Ionic Selectivity and Permeation Properties of Human PIEZO1 Channels

    PubMed Central

    Gnanasambandam, Radhakrishnan; Bae, Chilman; Gottlieb, Philip A.; Sachs, Frederick

    2015-01-01

    Members of the eukaryotic PIEZO family (the human orthologs are noted hPIEZO1 and hPIEZO2) form cation-selective mechanically-gated channels. We characterized the selectivity of human PIEZO1 (hPIEZO1) for alkali ions: K+, Na+, Cs+ and Li+; organic cations: TMA and TEA, and divalents: Ba2+, Ca2+, Mg2+ and Mn2+. All monovalent ions permeated the channel. At a membrane potential of -100 mV, Cs+, Na+ and K+ had chord conductances in the range of 35–55 pS with the exception of Li+, which had a significantly lower conductance of ~ 23 pS. The divalents decreased the single-channel permeability of K+, presumably because the divalents permeated slowly and occupied the open channel for a significant fraction of the time. In cell-attached mode, 90 mM extracellular divalents had a conductance for inward currents carried by the divalents of: 25 pS for Ba2+ and 15 pS for Ca2+ at -80 mV and 10 pS for Mg2+ at -50 mV. The organic cations, TMA and TEA, permeated slowly and attenuated K+ currents much like the divalents. As expected, the channel K+ conductance increased with K+ concentration saturating at ~ 45 pS and the KD of K+ for the channel was 32 mM. Pure divalent ion currents were of lower amplitude than those with alkali ions and the channel opening rate was lower in the presence of divalents than in the presence of monovalents. Exposing cells to the actin disrupting reagent cytochalasin D increased the frequency of openings in cell-attached patches probably by reducing mechanoprotection. PMID:25955826

  14. Feasibility of permeation grouting for constructing subsurface barriers

    SciTech Connect

    Dwyer, B.P.

    1994-04-01

    Efforts are being made to devise technologies that provide interim containment of waste sites while final remediation alternatives are developed. Permeation grouting, a technique used extensively in the civil and mining engineering industry has been investigated as a method for emplacing a subsurface containment barrier beneath existing waste sites. Conceptually an underlying barrier is placed by injecting grout into the formation at less than fracturing pressure from a series of directionally drilled boreholes beneath the waste site. This study evaluated the penetration and performance characteristics in varying soil conditions of four different grout materials (two microfine cements, mineral wax, and sodium silicate) at a field scale. Field testing consisted of grout injection via sleeve (tube-a`-manchette) pipe into both vertical and horizontal borehole configurations at the Mixed Waste Landfill Integrated Demonstration site at Sandia National Laboratories. Prior to, during, and after grout injection non-intrusive geophysical techniques were used to map grout flow. Following the tests, the site was excavated to reveal details of the grout permeation, and grouted soil samples were cored for laboratory characterization. The non-intrusive and intrusive grout mapping showed preferential flow patterns, i.e., the grout tended to follow the path of least resistance. Preliminary testing indicates that permeation grouting is a feasible method for emplacing a low permeability subsurface barrier in the semi-arid unconsolidated alluvial soils common to the Southwest. Despite the success of this project, difficulties in predicting grout flow in heterogeneous soils and non-intrusive methods for imaging grout location and continuity are issues that need more attention.

  15. Computational Studies of Molecular Permeation through Connexin26 Channels.

    PubMed

    Luo, Yun; Rossi, Angelo R; Harris, Andrew L

    2016-02-01

    A signal property of connexin channels is the ability to mediate selective diffusive movement of molecules through plasma membrane(s), but the energetics and determinants of molecular movement through these channels have yet to be understood. Different connexin channels have distinct molecular selectivities that cannot be explained simply on the basis of size or charge of the permeants. To gain insight into the forces and interactions that underlie selective molecular permeation, we investigated the energetics of two uncharged derivatized sugars, one permeable and one impermeable, through a validated connexin26 (Cx26) channel structural model, using molecular dynamics and associated analytic tools. The system is a Cx26 channel equilibrated in explicit membrane/solvent, shown by Brownian dynamics to reproduce key conductance characteristics of the native channel. The results are consistent with the known difference in permeability to each molecule. The energetic barriers extend through most of the pore length, rather than being highly localized as in ion-specific channels. There is little evidence for binding within the pore. Force decomposition reveals how, for each tested molecule, interactions with water and the Cx26 protein vary over the length of the pore and reveals a significant contribution from hydrogen bonding and interaction with K(+). The flexibility of the pore width varies along its length, and the tested molecules have differential effects on pore width as they pass through. Potential sites of interaction within the pore are defined for each molecule. The results suggest that for the tested molecules, differences in hydrogen bonding and entropic factors arising from permeant flexibility substantially contribute to the energetics of permeation. This work highlights factors involved in selective molecular permeation that differ from those that define selectivity among atomic ions. PMID:26840724

  16. Molecular dynamics simulations of water permeation across Nafion membrane interfaces.

    PubMed

    Daly, Kevin B; Benziger, Jay B; Panagiotopoulos, Athanassios Z; Debenedetti, Pablo G

    2014-07-24

    Permeation of water across the membrane/vapor and membrane/liquid-water interfaces of Nafion is studied using nonequilibrium molecular dynamics (NEMD) simulations, providing direct calculations of mass-transfer resistance. Water mass transfer within one nanometer of the vapor interface is shown to be 2 orders of magnitude slower than at any other point within the membrane, in qualitative agreement with permeation experiments. This interfacial resistance is much stronger than the resistance suggested by prior simulation work calculating self-diffusivity near the interface. The key difference between the prior approach and the NEMD approach is that the NEMD approach implicitly incorporates changes in solubility in the direction normal to the interface. Water is shown to be very insoluble near the vapor interface, which is rich in hydrophobic perfluorocarbon chains, in agreement with advancing contact angle experiments. Hydrophilic side chains are buried beneath this hydrophobic layer and aligned toward the interior of the membrane. Hydrophilic pores are not exposed to the vapor interface as proposed in prior theoretical work. At the membrane/liquid-water interface, highly swollen polymer chains extend into the liquid-water phase, forming a nanoscopically rough interface that is consistent with atomic force microscopy experiments. In these swollen conformations, hydrophilic side chains are exposed to the liquid-water phase, suggesting that the interface is hydrophilic, in agreement with receding contact angle experiments. The mass-transfer resistance of this interface is negligible compared to that of the bulk, in qualitative agreement with permeation experiments. The water activity at the vapor and liquid-water interfaces are nearly the same, yet large conformational and transport differences are observed, consistent with a mass-transfer-based understanding of Schroeder's paradox for Nafion. PMID:24971638

  17. Comparison of permeating and nonpermeating cryoprotectants for mouse sperm cryopreservation.

    PubMed

    Sztein, J M; Noble, K; Farley, J S; Mobraaten, L E

    2001-02-01

    Mouse sperm has proven to be more difficult to cryopreserve than sperm of other mammalian species. Published reports show that only three cryoprotectant agents (CPAs), alone or combined, have been studied: glycerol and dimethyl sulfoxide (DMSO), as permeating agents, and raffinose, as a nonpermeating agent. To date, the most consistent results for mouse sperm cryopreservation have been achieved by use of raffinose/skim milk as cryoprotectant with rapid cooling at 20 degrees C per minute. In this study, we compared the cryoprotection provided by permeating (glycerol, formamide, propanediol, DMSO, adonitol) or nonpermeating (lactose, raffinose, sucrose, trehalose, d-mannitol) compounds for freezing mouse sperm. Different solutions were made using 3% skim milk solution as the buffer or extender in which all different cryoprotectant agents were dissolved at a concentration of 0.3 M, with a final osmolality of approx. 400 mOsm. Sperm samples from CB6F1 (hybrid) and C57BL/6J (inbred) mice collected directly into each CPA were frozen/thawed under identical conditions. After thawing and CPA elimination (centrifugation) raffinose (59%), trehalose (61%), and sucrose (61%) sustained the best motility (P = < 0.1) of the nonpermeating agents, whereas the best of the permeating agents was DMSO (42%). Membrane integrity was analyzed and showed that the simple exposure (prefreeze) to sugars was less harmful than the exposure to glycols. Coincidentally, sperm frozen in trehalose (41%), raffinose (40.5%), and sucrose (37.5%) were the samples less injured among all different postthawed CPA tested. The in vitro fertilization results demonstrated that hybrid mouse spermatozoa frozen with sugars (lactose 80%, raffinose 80%, trehalose 79% of two-cell embryos production) were more fertile than those frozen with glycols (glycerol 11%). PMID:11336487

  18. Permeation of dimethyl sulfoxide into articular cartilage at subzero temperatures.

    PubMed

    Zhang, Shao-Zhi; Yu, Xiao-Yi; Chen, Guang-Ming

    2012-03-01

    Osteochondral allografting has been proved to be a useful method to treat diseased or damaged areas of joint surfaces. Operational long-term stocks of grafts which supply a buffer between procurement and utilization would contribute to the commercialization or industrialization of this technology. Vitrification has been thought to be a promising method for successful preservation of articular cartilage (AC), but high concentration cryoprotectants (CPAs) are used which may cause high cellular toxicity. An effective way to reduce CPA toxicity is to increase CPA concentration gradually while the temperature is lowered. Understanding the mechanism of CPA permeation at subzero temperatures is important for designing the cryopreservation protocol. In this research, the permeation of dimethyl sulfoxide (Me(2)SO) in ovine AC at subzero temperatures was studied experimentally. Pretreated AC discs were exposed in Me(2)SO solutions for different time (0, 5, 15, 30, 50, 80, and 120 min) at three temperature levels (-10, -20, and -30 °C). The Me(2)SO concentration within the tissue was determined by ultraviolet (UV) spectrophotometry. The diffusion coefficients were estimated to be 0.85×10(-6), 0.48×10(-6), and 0.27×10(-6) cm(2)/s at -10, -20, and -30 °C, respectively, and the corresponding activation energy was 29.23 kJ/mol. Numerical simulation was performed to compare two Me(2)SO addition protocols, and the results demonstrated that the total loading duration could be effectively reduced with the knowledge of permeation kinetics. PMID:22374614

  19. Increased regional vascular albumin permeation in the rat during anaphylaxis

    SciTech Connect

    Leng, W.; Chang, K.; Williamson, J.R.; Jakschik, B.A.

    1989-03-15

    The changes in vascular albumin permeation induced by systemic anaphylaxis were studied simultaneously in 21 different tissues of the same animal. Before Ag challenge sensitized rats were injected i.v. with 125I-albumin (test tracer), 51Cr-RBC (vascular space marker) and 57Co-EDTA (extravascular space marker). The index of vascular permeation used was the tissue to blood isotope ratio (tbir), which was obtained by dividing the ratio of 125I/51Cr counts in each tissue by the ratio of the same isotopes in the arterial blood sample. After Ag challenge, the increase in the tbir varied considerably among the different tissues. The most pronounced increase was noted in the lymph node (ninefold) followed by the aorta and mesentery (six- to sevenfold) and the various parts of the gastrointestinal tract (four- to sixfold). In the skin less than skeletal muscle less than lung less than liver and eye two- to fourfold increases occurred. Relatively minor increases in albumin permeation (less than twofold) were observed in the brain less than kidney less than heart and less than spleen. The testis was the only organ in which no significant change occurred. For some of the tissues there was also an increase in the tbir for 57Co/51Cr (an index of the extracellular fluid space) suggesting edema formation. The highest increase was noted in the aorta (fourfold). Minor increases occurred in the atrium of the heart, stomach, duodenum, and lymph nodes. There was also a 36% increase in hematocrit. Therefore, systemic anaphylaxis caused extensive extravasation of albumin and hemoconcentration.

  20. The human nail--barrier characterisation and permeation enhancement.

    PubMed

    Walters, Kenneth A; Abdalghafor, Haydar M; Lane, Majella E

    2012-10-01

    The human nail remains one of the most challenging membranes for formulation scientists to target and for clinicians to heal. Its formidable barrier properties are the primary reason that oral therapy remains the primary approach to manage ungual infections. This article considers the major structural properties underlying the excellent barrier function of the nail, with particular emphasis on the role of biophysical methods in advancing our knowledge of this appendage. Formulations currently available for management of ungual disease are discussed and their therapeutic efficacy is assessed. Finally, experimental strategies to enhance ungual permeation are reviewed and prospects for future developments in the field are considered. PMID:22521879

  1. Anion Permeation in Ca2+-Activated Cl− Channels

    PubMed Central

    Qu, Zhiqiang; Hartzell, H. Criss

    2000-01-01

    Ca2+-activated Cl channels (ClCaCs) are an important class of anion channels that are opened by increases in cytosolic [Ca2+]. Here, we examine the mechanisms of anion permeation through ClCaCs from Xenopus oocytes in excised inside-out and outside-out patches. ClCaCs exhibited moderate selectivity for Cl over Na: PNa/PCl = 0.1. The apparent affinity of ClCaCs for Cl was low: Kd = 73 mM. The channel had an estimated pore diameter >0.6 nm. The relative permeabilities measured under bi-ionic conditions by changes in Erev were as follows: C(CN)3 > SCN > N(CN)2 > ClO4 > I > N3 > Br > Cl > formate > HCO3 > acetate = F > gluconate. The conductance sequence was as follows: N3 > Br > Cl > N(CN)2 > I > SCN > COOH > ClO4 > acetate > HCO3 = C(CN)3 > gluconate. Permeant anions block in a voltage-dependent manner with the following affinities: C(CN)3 > SCN = ClO4 > N(CN)2 > I > N3 > Br > HCO3 > Cl > gluconate > formate > acetate. Although these data suggest that anionic selectivity is determined by ionic hydration energy, other factors contribute, because the energy barrier for permeation is exponentially related to anion hydration energy. ClCaCs exhibit weak anomalous mole fraction behavior, implying that the channel may be a multi-ion pore, but that ions interact weakly in the pore. The affinity of the channel for Ca2+ depended on the permeant anion at low [Ca2+] (100–500 nM). Apparently, occupancy of the pore by a permeant anion increased the affinity of the channel for Ca2+. The current was strongly dependent on pH. Increasing pH on the cytoplasmic side decreased the inward current, whereas increasing pH on the external side decreased the outward current. In both cases, the apparent pKa was voltage-dependent with apparent pKa at 0 mV = ∼9.2. The channel may be blocked by OH− ions, or protons may titrate a site in the pore necessary for ion permeation. These data demonstrate that the permeation properties of ClCaCs are different from those of CFTR or ClC-1, and provide

  2. Brownian dynamics simulation for modeling ion permeation across bionanotubes.

    PubMed

    Krishnamurthy, Vikram; Chung, Shin-Ho

    2005-03-01

    The principles underlying Brownian dynamics (BD), its statistical consistency, and algorithms for practical implementation are outlined here. The ability to compute current flow across ion channels confers a distinct advantage to BD simulations compared to other simulation techniques. Thus, two obvious applications of BD ion channels are in calculation of the current-voltage and current-concentration curves, which can be directly compared to the physiological measurements to assess the reliability of the model and predictive power of the method. We illustrate how BD simulations are used to unravel the permeation dynamics in two biological ion channels-the KcsA K+ channel and CIC Cl- channel. PMID:15816176

  3. Evaluation of sunscreen safety by in vitro skin permeation studies: effects of vehicle composition.

    PubMed

    Montenegro, L; Puglisi, G

    2013-01-01

    For sunscreens to be safe and effective, the lowest possible UV-filter percutaneous absorption should be achieved. In this paper, we evaluated in vitro release and permeation through human skin of two UV-filters, octyl methoxycinnammate (OMC) and butyl methoxydibenzoyl methane (BMBM) from six commercial O/W emulsions and we estimated their margin of safety (MoS). OMC and BMBM in vitro release and skin permeation were investigated in Franz-type diffusion cells and permeation data were used to calculate MoS. OMC in vitro skin permeation depended on both its concentration and vehicle composition while BMBM skin permeation depended on its release from the vehicle. MoS values were well beyond the lowest limit accepted for safe products. Although sunscreen skin permeation may depend on many factors, the commercial products investigated are safe under normal "in use" conditions. PMID:23444778

  4. Design and tritium permeation analysis of China HCCB TBM port cell

    SciTech Connect

    Jiangfeng, S.; Guoqiang, H.; Zhiyong, H.; Chang'an, C.; Deli, L.

    2015-03-15

    China is planning to develop a helium-cooled ceramic breeder (HCCB) test blanket module (TBM) on ITER to test key blanket technologies. In this paper, the design and tritium permeation analysis of China HCCB TBM port cell are introduced. A theoretical model has been developed to estimate tritium permeation rates and leak rates from the components and pipes which China has scheduled to house in the port cell. It is shown that on normal working conditions, the permeation and leak rate of the systems in the port cell will be no higher than 1.58 Ci/d without the use of tritium permeation barriers, and 0.10 Ci/d with the use of tritium permeation barriers. It also appears that tritium permeation barriers are necessary for high temperature components such as the reduction bed and the heater.

  5. Influence of membrane-solvent-solute interactions on solute permeation in skin.

    PubMed

    Dias, M; Hadgraft, J; Lane, M E

    2007-08-01

    The relative importance of solubility parameters and other solvent properties on membrane diffusion processes has not been fully elucidated in the literature. Previously, we have studied the effect of different vehicles on the permeation of caffeine, benzoic acid (BA) and salicylic acid (SA) through silicone membranes. The present paper investigates diffusion of the selected permeants from different saturated solutions through human epidermis. The permeation of caffeine was strongly affected by the vehicle chosen and the maximum enhancement observed for the permeation of caffeine was 288-fold. A maximum of 12-fold enhancement in the flux was observed for the permeation of SA and a maximum of 10-fold enhancement was observed for the permeation of BA. The diffusion profiles obtained for SA in the different solvents were very similar when compared with those obtained for BA but the permeation rates were higher for BA than for SA. This similarity results from the similar chemical structure and lipophilicity. PMID:17467936

  6. Articles of protective clothing adapted for deflecting chemical permeation and methods there for

    DOEpatents

    Vo-Dinh, T.

    1996-02-27

    Apparatus and methods for detecting the permeation of hazardous or toxic chemicals through protective clothing are disclosed. The hazardous or toxic chemicals of interest do not possess the spectral characteristic of luminescence. The apparatus and methods utilize a spectrochemical modification technique to detect the luminescence quenching of an indicator compound which upon permeation of the chemical through the protective clothing, the indicator is exposed to the chemical, thus indicating chemical permeation. 12 figs.

  7. Articles of protective clothing adapted for deflecting chemical permeation and methods therefor

    DOEpatents

    Vo-Dinh, Tuan

    1996-01-01

    Apparatus and methods for detecting the permeation of hazardous or toxic chemicals through protective clothing are disclosed. The hazardous or toxic chemicals of interest do not possess the spectral characteristic of luminescence. The apparatus and methods utilize a spectrochemical modification technique to detect the luminescence quenching of an indicator compound which upon permeation of the chemical through the protective clothing, the indicator is exposed to the chemical, thus indicating chemical permeation.

  8. Room-temperature phosphorimetry to study petroleum product permeation through protective clothing materials

    SciTech Connect

    White, D.A.; Vo-Dinh, T.

    1988-02-01

    In this study a simple analytical tool based on room-temperature phosphorimetry (RTP) is developed and used for evaluating the effectiveness of protective clothing materials against permeation of organic substances containing compounds such as the polycyclic aromatic compounds. A special permeation cell is designed, which allows direct RTP measurements of the permeated products after exposure, without requiring any sample extraction procedure. Results for a variety of petroleum product-protective material combinations illustrate the usefulness of the technique.

  9. Tritium permeation characterization of Al2O3/FeAl coatings as tritium permeation barriers on 321 type stainless steel containers

    NASA Astrophysics Data System (ADS)

    Yang, Feilong; Xiang, Xin; Lu, Guangda; Zhang, Guikai; Tang, Tao; Shi, Yan; Wang, Xiaolin

    2016-09-01

    Accurate tritium transport properties of prospective tritium permeation barriers (TPBs) are essential to tritium systems in fusion reactors. By passing a temperature and rate-controlled sweeping gas over specimen surfaces to carry the permeated tritium to an ion chamber, the gas-driven permeation of tritium has been performed on 321 type stainless steel containers with Al2O3/FeAl barriers, to determine the T-permeation resistant performance and mechanism of the barrier. The tritium permeability of the Al2O3/FeAl coated container was reduced by 3 orders of magnitude at 500-700 °C by contrast with that of the bare one, which meets the requirement of the tritium permeation reduction factor (PRF) of TPBs for tritium operating components in the CN-HCCB TBM. The Al2O3/FeAl barrier resists the tritium permeation by the diffusion in the bulk substrate at a limited number of defect sites with an effective area and thickness, suggesting that the TPB quality is a very important factor for efficient T-permeation resistance.

  10. Gas permeation of LC films observed by smectic bubble expansion.

    PubMed

    Ishii, Y; Tabe, Y

    2009-11-01

    Gas permeation through liquid crystal (LC) films was examined using hemispherical smectic bubbles. A smectic bubble, when the inside and the outside are filled with different gases, should expand or shrink toward the quasi-equilibrium state, where the influx and efflux caused by osmotic pressure are balanced. Deriving a simple formula that directly converts the quasi-equilibrated bubble radius to the gas permeation, we determined the absolute permeability coefficients of 8 simple gases through the smectic bubble. The permeability was distributed in such a wide range that carbon-dioxide had more than 20 times larger value than nitrogen, the dependence of which on the gas species was mostly dominated by their solubility into the LCs. Dividing the measured permeability by the calculated solubility, we obtained the diffusion constants as well, yet whose magnitude and the dependence on the solute size could not be explained by either conventional continuum theories or microscopic diffusion models. In order to describe the diffusion of small solutes in the liquid solvent composed of large molecules, a new theoretical framework may be necessary. PMID:19816725

  11. Omniphobic low moisture permeation transparent polyacrylate/silica nanocomposite.

    PubMed

    Hsu, Sheng-Hao; Chang, Yuan-Ling; Tu, Yu-Chieh; Tsai, Chieh-Ming; Su, Wei-Fang

    2013-04-24

    We report the development of low moisture permeation and transparent dense polyacrylate/silica nanocomposite material that can exhibit both superhydrophobic and oleophobic (omniphobic) properties. The material was prepared by a three-step process. The first step involved the preparation of UV polymerizable solventless hybrid resin and the fabrication of nanocomposite. The hybrid resin consisted of a mixture of acrylate monomer, initiator, and acrylate-modified different size silica nanoparticles. The second step was to roughen the surface of the nanocomposite with unique nanotexture by oxygen plasma. In the third step, we applied a low surface tension fluoro monolayer on the treated surface. The nanocomposite exhibits desired superhydrophobicity and oleophobicity with a water contact angle of 158.2° and n-1-octadecene contact angle of 128.5°, respectively; low moisture permeation of 1.44 g·mm/m(2)·day; and good transparency (greater than 82% at 450-800 nm for ~60 μm film). The material has potential applications in optoelectronic encapsulation, self-cleaning coating, etc. PMID:23496768

  12. A review of water recovery by vapour permeation through membranes.

    PubMed

    Bolto, Brian; Hoang, Manh; Xie, Zongli

    2012-02-01

    In vapour permeation the feed is a vapour, not a liquid as in pervaporation. The process employs a polymeric membrane as a semi-permeable barrier between the feed side under high pressure and the permeate side under low pressure. Separation is achieved by the different degrees to which components are dissolved in and diffuse through the membrane, the system working according to a solution-diffusion mechanism. The materials used in the membrane depend upon the types of compounds being separated, so water transport is favoured by hydrophilic material, whether organic or inorganic. The process is used for the dehydration of natural gas and various organic solvents, notably alcohol as biofuel, as well as the removal of water from air and its recovery from waste steam. Waste steam can be found in almost every plant/factory where steam is used. It is frequently contaminated and cannot be reused. Discharging the spent steam to the atmosphere is a serious energy loss and environmental issue. Recycling the steam can significantly improve the overall energy efficiency of an industry, which is responsible for massive CO(2) emissions. Steam separation at high fluxes and temperatures has been accomplished with a composite poly(vinyl alcohol) membrane containing silica nanoparticles, and also, less efficiently, with an inorganic zeolite membrane. PMID:22100055

  13. Permeation Resistance of Personal Protective Equipment Materials to Monomethyhydrazine

    NASA Technical Reports Server (NTRS)

    Waller, J. M.; Williams, J. H.

    1997-01-01

    Permeation resistance was determined by measuring the breakthrough time and time-averaged vapor transmission rate of monomethylhydrazine (MMH) through two types of personal protective equipment (PPE). The two types of PPE evaluated were the totally encapsulating ILC Dover Chemturion Model 1212 chemical protective suit with accessories, and the FabOhio polyvinyl chloride (PVC) splash garment. Two exposure scenarios were simulated: (1) a saturated vapor exposure for 2 hours (h), and (2) a brief MMH 'splash' followed by a 2-h saturated vapor exposure. Time-averaged MMH concentrations inside the totally-encapsulating suit were calculated by summation of the area-weighted contributions made by each suit component. Results show that the totally encapsulating suit provides adequate protection at the new 10 ppb Threshold Limit Value Time-Weighted Average (TLV-TWA). The permeation resistance of the PVC splash garment to MMH was poorer than any of the totally encapsulating suit materials tested. Breakthrough occurred soon after initial vapor or 'splash' exposure.

  14. Hydrogen permeation characteristics of some Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Van Deventer, E. H.; Maroni, V. A.

    1983-01-01

    Hydrogen permeation data are reported for two Fe-Cr-Al alloys, Type-405 SS (Cr 14-A1 0.2) and a member of the Fecralloy family of alloys (Cr 16-A1 5). The hydrogen permeability of each alloy (in a partially oxidized condition) was measured over a period of several weeks at randomly selected temperatures (between 150 and 850°C) and upstream H 2 pressures (between 2 and 1.5 × 10 4 Pa). The permeabilities showed considerable scatter with both time and temperature and were 10 2 to 10 3 times lower than those of pure iron, even in strongly reducing environments. The exponent, n, for the relationship between upstream H 2 pressure, P, and permeability, φ, ( φ ~ Pn) was closer to 0.7 than to the expected 0.5, indicating a process limited by surface effects (e.g., surface oxide films) as opposed to bulk material effects. Comparison of these results with prior permeation measurements on other Fe-Cr-Al alloys, on Fe-Cr alloys, and on pure iron shows that the presence of a few weight percent aluminum offers the best prospects for achieving low tritium permeabilities with martensitic and ferritic steels used in fusion-reactor first wall and blanket applications.

  15. Simulation of Nanoparticle Permeation through a Lipid Membrane

    PubMed Central

    Fiedler, Steven L.; Violi, Angela

    2010-01-01

    Abstract A metric of nanoparticle toxicity is the passive permeability rate through cellular membranes. To assess the influence of nanoparticle morphology on this process, the permeability of buckyball-sized molecules through a representative lipid bilayer was investigated by molecular-dynamics simulation. When C60 was compared with a prototypical opened C60 molecule and a representative combustion-generated particle, C68H29, the calculated free-energy profiles along the permeation coordinate revealed a sizable variation in form and depth. The orientation of the anisotropic molecules was determined by monitoring the principal axis corresponding to the largest moment of inertia, and free rotation was shown to be hindered in the bilayer interior. Diffusion constant values of the permeant molecules were calculated from a statistical average of seven to 10 trajectories at five locations along the permeation coordinate. A relatively minor variation of the values was observed in the bilayer interior; however, local resistance values spanned up to 24 orders of magnitude from the water layer to the bilayer center, due primarily to its exponential dependence on free energy. The permeability coefficient values calculated for the three similarly sized but structurally distinct nanoparticles showed a significant variance. The use of C60 to represent similarly sized carbonaceous nanoparticles for assessments of toxicity is questioned. PMID:20655842

  16. Improved skin permeation of methotrexate via nanosized ultradeformable liposomes.

    PubMed

    Zeb, Alam; Qureshi, Omer Salman; Kim, Hyung-Seo; Cha, Ji-Hye; Kim, Hoo-Seong; Kim, Jin-Ki

    2016-01-01

    The aim of this study is to investigate methotrexate-entrapped ultradeformable liposomes (MTX-UDLs) for potential transdermal application. MTX-UDLs were prepared by extrusion method with phosphatidylcholine as a bilayer matrix and sodium cholate or Tween 80 as an edge activator. The physicochemical properties of MTX-UDLs were determined in terms of particle size, polydispersity index, zeta potential, and entrapment efficiency. The deformability of MTX-UDLs was compared with that of methotrexate-entrapped conventional liposomes (MTX-CLs) using a steel pressure filter device. The skin permeation of MTX-UDLs was investigated using Franz diffusion cell, and the skin penetration depth of rhodamine 6G-entrapped UDLs was determined by confocal laser scanning microscopy. MTX-UDLs showed a narrow size distribution, with the particle size of ~100 nm. The deformability of MTX-UDLs was two to five times greater than that of MTX-CLs. The skin permeation of MTX-UDLs was significantly improved compared with MTX-CLs and free MTX solution. The optimized UDLs (phosphatidylcholine: Tween 80 =7:3, w/w) showed a higher fluorescence intensity than conventional liposomes at every increment of skin depth. Thus, the optimized UDLs could be promising nanocarriers for systemic delivery of MTX across skin. PMID:27540293

  17. Ultrafast permeation of water through protein-based membranes.

    PubMed

    Peng, Xinsheng; Jin, Jian; Nakamura, Yoshimichi; Ohno, Takahisa; Ichinose, Izumi

    2009-06-01

    Pressure-driven filtration by porous membranes is widely used in the production of drinking water from ground and surface water. Permeation theory predicts that filtration rate is proportional to the pressure difference across the filtration membrane and inversely proportional to the thickness of the membrane. However, these membranes need to be able to withstand high water fluxes and pressures, which means that the active separation layers in commercial filtration systems typically have a thickness of a few tens to several hundreds of nanometres. Filtration performance might be improved by the use of ultrathin porous silicon membranes or carbon nanotubes immobilized in silicon nitride or polymer films, but these structures are difficult to fabricate. Here, we report a new type of filtration membrane made of crosslinked proteins that are mechanically robust and contain channels with diameters of less than 2.2 nm. We find that a 60-nm-thick membrane can concentrate aqueous dyes from fluxes up to 9,000 l h(-1) m(-2) bar(-1), which is approximately 1,000 times higher than the fluxes that can be withstood by commercial filtration membranes with similar rejection properties. Based on these results and molecular dynamics simulations, we propose that protein-surrounded channels with effective lengths of less than 5.8 nm can separate dye molecules while allowing the ultrafast permeation of water at applied pressures of less than 1 bar. PMID:19498395

  18. Improved skin permeation of methotrexate via nanosized ultradeformable liposomes

    PubMed Central

    Zeb, Alam; Qureshi, Omer Salman; Kim, Hyung-Seo; Cha, Ji-Hye; Kim, Hoo-Seong; Kim, Jin-Ki

    2016-01-01

    The aim of this study is to investigate methotrexate-entrapped ultradeformable liposomes (MTX-UDLs) for potential transdermal application. MTX-UDLs were prepared by extrusion method with phosphatidylcholine as a bilayer matrix and sodium cholate or Tween 80 as an edge activator. The physicochemical properties of MTX-UDLs were determined in terms of particle size, polydispersity index, zeta potential, and entrapment efficiency. The deformability of MTX-UDLs was compared with that of methotrexate-entrapped conventional liposomes (MTX-CLs) using a steel pressure filter device. The skin permeation of MTX-UDLs was investigated using Franz diffusion cell, and the skin penetration depth of rhodamine 6G-entrapped UDLs was determined by confocal laser scanning microscopy. MTX-UDLs showed a narrow size distribution, with the particle size of ~100 nm. The deformability of MTX-UDLs was two to five times greater than that of MTX-CLs. The skin permeation of MTX-UDLs was significantly improved compared with MTX-CLs and free MTX solution. The optimized UDLs (phosphatidylcholine: Tween 80 =7:3, w/w) showed a higher fluorescence intensity than conventional liposomes at every increment of skin depth. Thus, the optimized UDLs could be promising nanocarriers for systemic delivery of MTX across skin. PMID:27540293

  19. Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash

    2013-03-01

    Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

  20. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... must meet the permeation requirements specified in 40 CFR 1048.105. (3) Fuel lines for recreational vehicles must meet the permeation requirements specified in 40 CFR 1051.110 or in this section. (4) Small... regulations in 40 CFR part 1048 require that fuel lines used with Large SI engines must meet the standards...

  1. Hydration of nail plate: a novel screening model for transungual drug permeation enhancers.

    PubMed

    Chouhan, P; Saini, T R

    2012-10-15

    Drug delivery by topical route for the treatment of onychomycosis, a nail fungal infection, is challenging due to the unique barrier properties of the nail plate which imparts high resistance to the passage of antifungal drugs. Permeation enhancers are used in transungual formulations to improve the drug flux across the nail plate. Selection of the effective permeation enhancer among the available large pool of permeation enhancers is a difficult task. Screening the large number of permeation enhancers using conventional Franz diffusion cells is laborious and expensive. The objective of present study was to evolve a simple, accurate and rapid method for screening of transungual drug permeation enhancers based on the principle of hydration of nail plate. The permeation enhancer which affects the structural or physicochemical properties of nail plate would also affect their hydration capacity. Two screening procedures namely primary and secondary screenings were evolved wherein hydration and uptake of ciclopirox olamine by nail plates were measured. Hydration enhancement factor, HEF(24) and drug uptake enhancement factor, UEF(24) were determined for screening of 23 typical permeation enhancers. The Pearson's correlation coefficient between HEF(24) and UEF(24) was determined. A good agreement between the HEF(24) and UEF(24) data proved the validity of the proposed nail plate hydration model as a screening technique for permeation enhancers. PMID:22705091

  2. Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

    PubMed

    Mao, Feng; Ong, Say Kee; Gaunt, James A

    2015-09-01

    Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes. PMID:26322761

  3. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... must meet the permeation requirements specified in 40 CFR 1048.105. (3) Fuel lines for recreational vehicles must meet the permeation requirements specified in 40 CFR 1051.110 or in this section. (4) Small... regulations in 40 CFR part 1048 require that fuel lines used with Large SI engines must meet the standards...

  4. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... must meet the permeation requirements specified in 40 CFR 1048.105. (3) Fuel lines for recreational vehicles must meet the permeation requirements specified in 40 CFR 1051.110 or in this section. (4) Small... regulations in 40 CFR part 1048 require that fuel lines used with Large SI engines must meet the standards...

  5. Tritium permeation and recovery for the helium-cooled molten salt fusion breeder

    SciTech Connect

    Sherwood, A.E.

    1984-09-01

    Design concepts are presented to control tritium permeation from a molten salt/helium fusion breeder reactor. This study assumes tritium to be a gas dissolved in molten salt, with TF formation suppressed. Tritium permeates readily through the hot steel tubes of the reactor and steam generator and will leak into the steam system at the rate of about one gram per day in the absence of special permeation barriers, assuming that 1% of the helium coolant flow rate is processed for tritium recovery at 90% efficiency per pass. The proposed permeation barrier for the reactor tubes is a 10 ..mu..m layer of tungsten which, in principle, will reduce tritium blanket permeation by a factor of about 300 below the bare-steel rate. A research and development effort is needed to prove feasibility or to develop alternative barriers. A 1 mm aluminum sleeve is proposed to suppress permeation through the steam generator tubes. This gives a calculated reduction factor of more than 500 relative to bare steel, including a factor of 30 due to an assumed oxide layer. The permeation equations are developed in detail for a multi-layer tube wall including a frozen salt layer and with two fluid boundary-layer resistances. Conditions are discussed for which Sievert's or Henry's Law materials become flux limiters. An analytical model is developed to establish the tritium split between wall permeation and reactor-tube flow.

  6. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... must meet the permeation requirements specified in 40 CFR 1048.105. (3) Fuel lines for recreational vehicles must meet the permeation requirements specified in 40 CFR 1051.110 or in this section. (4) Small... regulations in 40 CFR part 1048 require that fuel lines used with Large SI engines must meet the standards...

  7. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... must meet the permeation requirements specified in 40 CFR 1048.105. (3) Fuel lines for recreational vehicles must meet the permeation requirements specified in 40 CFR 1051.110 or in this section. (4) Small... regulations in 40 CFR part 1048 require that fuel lines used with Large SI engines must meet the standards...

  8. Permeation of herbicidal dichlobenil from a Casoron formulation through nitrile gloves.

    PubMed

    Que Hee, Shane S; Zainal, Hanaa

    2010-02-01

    The aim of this study was to measure permeation of the herbicide dichlobenil in Casoron 4G through disposable and chemically protective nitrile gloves using an American Society for Testing and Materials-type permeation cell and a closed-loop system employing two different solvents (hexane and water) and two different challenge situations (aqueous emulsion and solid formulation). Capillary gas chromatography-mass spectrometry was used for quantification purposes. The chemically protective glove did not allow any permeation up to 8 h for the solid-formulation and water-collection challenges, but permeation was detected in all other challenges. The disposable glove allowed the most permeation, and the solid-formulation challenge with water collection necessitated that a dichlobenil equivalent be calculated because of the presence of its hydrolysis degradation product 2,6-dichlorobenzamide. Permeation from the solid formulation was detectable by hexane collection for both the disposable and chemically protective gloves and by water collection for the disposable glove. It was concluded that hexane-solvent collection was not valid for the disposable glove at 4 and 8 h of permeation in the solid Casoron challenge or for the aqueous emulsion challenge at 8 h relative to the water-collection solvent data. The hexane-solvent collection for the chemically protective glove was valid for the 8-h solid-formulation challenge but not for the 8-h aqueous-solution challenge. All water-solvent collections were valid; however, dichlobenil usually permeated the gloves. PMID:19855916

  9. Micro encapsulation in situ with super permeating molten wax

    SciTech Connect

    Carter, E.

    2007-07-01

    A new class of grout material based on molten wax offers a dramatic improvement in permeation grouting performance. This new material makes a perfect in situ containment of buried radioactive waste both feasible and cost effective. This paper describes various ways the material can be used to isolate buried waste in situ. Potential applications described in the paper include buried radioactive waste in deep trenches, deep shafts, Infiltration trenches, and large buried objects. Use of molten wax for retrieval of waste is also discussed. Wax can also be used for retrieval of air sensitive materials or drummed waste. This paper provides an analysis of the methods of application and the expected performance and cost of several potential projects. (authors)

  10. Transient permeation of organic vapors through elastomeric membranes

    NASA Technical Reports Server (NTRS)

    Curry, J. E.

    1973-01-01

    The permeation of benzene and acetone vapors through sulfur-cured natural rubber was studied by the time-lag method. The zero concentration diffusion coefficient, was obtained by the early-time method. The Frisch time lag equation was utilized to estimate both the solubility coefficient and the additional parameter required to define the concentration-dependence of the diffusion coefficient. This form of concentration dependence was manifested by the corresponding permeability coefficient values. At low entering penetrant pressure where the transport coefficients are constant, indirect evidence was obtained that zero diffusion coefficient is the mechanically correct diffusion coefficient. The solubility coefficient values calculated for benzene vapor in natural rubber are in reasonable agreement with published equilibrium sorption data for a similar rubber compound. At higher entering penetrant pressures, average diffusion coefficients obtained at steady state tended to be larger than the corresponding average diffusion coefficients derived from the time-lags.

  11. The CFTR Ion Channel: Gating, Regulation, and Anion Permeation

    PubMed Central

    Hwang, Tzyh-Chang; Kirk, Kevin L.

    2013-01-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-gated anion channel with two remarkable distinctions. First, it is the only ATP-binding cassette (ABC) transporter that is known to be an ion channel—almost all others function as transport ATPases. Second, CFTR is the only ligand-gated channel that consumes its ligand (ATP) during the gating cycle—a consequence of its enzymatic activity as an ABC transporter. We discuss these special properties of CFTR in the context of its evolutionary history as an ABC transporter. Other topics include the mechanisms by which CFTR gating is regulated by phosphorylation of its unique regulatory domain and our current view of the CFTR permeation pathway (or pore). Understanding these basic operating principles of the CFTR channel is central to defining the mechanisms of action of prospective cystic fibrosis drugs and to the development of new, rational treatment strategies. PMID:23284076

  12. Water permeation through single-layer graphyne membrane.

    PubMed

    Kou, Jianlong; Zhou, Xiaoyan; Chen, Yanyan; Lu, Hangjun; Wu, Fengmin; Fan, Jintu

    2013-08-14

    We report the molecular dynamics simulations of spontaneous and continuous permeation of water molecules through a single-layer graphyne-3 membrane. We found that the graphyne-3 membrane is more permeable to water molecules than (5, 5) carbon nanotube membranes of similar pore diameter. The remarkable hydraulic permeability of the single-layer graphyne-3 membrane is attributed to the hydrogen bond formation, which connects the water molecules on both sides of the monolayer graphyne-3 membrane and aids to overcome the resistance of the nanopores, and to the relatively lower energy barrier at the pore entrance. Consequently, the single-layer graphyne-3 membrane has a great potential for application as membranes for desalination of sea water, filtration of polluted water, etc. PMID:23947878

  13. Gas permeation and performance of an FRP cryostat

    NASA Astrophysics Data System (ADS)

    Okada, Toichi; Nishijima, Shigehiro; Fujioka, Kouji; Kuraoka, Yasurou

    The causes of degradation in the vacuum within an FRP cryostat, a device useful in aerospace engineering because of its light weight, were studied experimentally from a materials science standpoint. It was found that gas diffusion practically does not occur at cryogenic temperatures. When gas permeation is induced at low temperatures, the main result is a gas leak due to a crack caused by thermal shock or thermal contraction. Reducing the bubbles in the FRP material during its manufacture should increase its crack resistance. Gas diffusion is a problem at room temperature because the helium gas diffusion rate is large considering the degree of vacuum. Increasing the glass content decreases the diffusion rate. Outgassing from FRP consists mainly of water from the FRP material. Baking reduces the water content in the FRP and increases its suitability for cryostats.

  14. The CFTR ion channel: gating, regulation, and anion permeation.

    PubMed

    Hwang, Tzyh-Chang; Kirk, Kevin L

    2013-01-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-gated anion channel with two remarkable distinctions. First, it is the only ATP-binding cassette (ABC) transporter that is known to be an ion channel--almost all others function as transport ATPases. Second, CFTR is the only ligand-gated channel that consumes its ligand (ATP) during the gating cycle--a consequence of its enzymatic activity as an ABC transporter. We discuss these special properties of CFTR in the context of its evolutionary history as an ABC transporter. Other topics include the mechanisms by which CFTR gating is regulated by phosphorylation of its unique regulatory domain and our current view of the CFTR permeation pathway (or pore). Understanding these basic operating principles of the CFTR channel is central to defining the mechanisms of action of prospective cystic fibrosis drugs and to the development of new, rational treatment strategies. PMID:23284076

  15. Ion Permeation and Mechanotransduction Mechanisms of Mechanosensitive Piezo Channels.

    PubMed

    Zhao, Qiancheng; Wu, Kun; Geng, Jie; Chi, Shaopeng; Wang, Yanfeng; Zhi, Peng; Zhang, Mingmin; Xiao, Bailong

    2016-03-16

    Piezo proteins have been proposed as the long-sought-after mechanosensitive cation channels in mammals that play critical roles in various mechanotransduction processes. However, the molecular bases that underlie their ion permeation and mechanotransduction have remained functionally undefined. Here we report our finding of the miniature pore-forming module of Piezo1 that resembles the pore architecture of other trimeric channels and encodes the essential pore properties. We further identified specific residues within the pore module that determine unitary conductance, pore blockage and ion selectivity for divalent and monovalent cations and anions. The non-pore-containing region of Piezo1 confers mechanosensitivity to mechano-insensitive trimeric acid-sensing ion channels, demonstrating that Piezo1 channels possess intrinsic mechanotransduction modules separate from their pore modules. In conclusion, this is the first report on the bona fide pore module and mechanotransduction components of Piezo channels, which define their ion-conducting properties and gating by mechanical stimuli, respectively. PMID:26924440

  16. Gel permeation chromatography (GPC) of repeatedly extruded polyethylene terephthalate (PET).

    PubMed

    Milana, M R; Denaro, M; Arrivabene, L; Maggio, A; Gramiccioni, L

    1998-04-01

    The paper deals with gel permeation chromatography (GPC) monitoring of the behaviour of PET (polyethylene terephthalate) after repeated extrusions. Virgin PET was submitted to three successive extrusion/drying cycles and then the samples were swelled with hexafluoroisopropanol and treated with chloroform. GPC analysis was carried out at room temperature on a B.C.S. Serial LC 2000 GPC system equipped with a series of four GPC columns with UV detection at 254 nm and chloroform as eluent. GPC results showed that after each extrusion step the molecular weight distribution of the PET was different and Mw, Mn and Mz decreased. These findings suggest that during each extrusion degradation occurs and that repeated extrusions, as in the case of the recycling PET, may cause an alteration of the molecular weight distribution of the original PET. PMID:9666895

  17. Molecular dynamics computer simulation of permeation in solids

    SciTech Connect

    Pohl, P.I.; Heffelfinger, G.S.; Fisler, D.K.; Ford, D.M.

    1997-12-31

    In this work the authors simulate permeation of gases and cations in solid models using molecular mechanics and a dual control volume grand canonical molecular dynamics technique. The molecular sieving nature of microporous zeolites are discussed and compared with that for amorphous silica made by sol-gel methods. One mesoporous and one microporous membrane model are tested with Lennard-Jones gases corresponding to He, H{sub 2}, Ar and CH{sub 4}. The mesoporous membrane model clearly follows a Knudsen diffusion mechanism, while the microporous model having a hard-sphere cutoff pore diameter of {approximately}3.4 {angstrom} demonstrates molecular sieving of the methane ({sigma} = 3.8 {angstrom}) but anomalous behavior for Ar ({sigma} = 3.4 {angstrom}). Preliminary results of Ca{sup +} diffusion in calcite and He/H{sub 2} diffusion in polyisobutylene are also presented.

  18. Temperature behaviour of permeation of helium through Vespel and Torlon

    NASA Astrophysics Data System (ADS)

    Schmidtchen, U.; Gradt, T.; Börner, H.; Behrend, E.

    Gases such as helium can diffuse through polymers in considerable amounts. The increasing use of polymers in cryogenic engineering may make it necessary to estimate the magnitude of this effect to judge whether it may be dangerous in vacuum insulations and the like. This paper reports measurements on the solubility and the diffusion constant of helium in two widely used polymers as a function of temperature. A continuous flow cryostat and a helium leak detector were the key elements of the experimental set-up. The results show that while the permeation flow of helium through polymers can be considerable at ambient temperature, it ceases to be a problem at temperatures of 200 K or below. For certain applications, however, this effect may be a serious problem and must be considered.

  19. Investigating effect of microemulsion components: In vitro permeation of ketoconazole.

    PubMed

    Patel, Mrunali R; Patel, Rashmin B; Parikh, Jolly R; Solanki, Ajay B; Patel, Bharat G

    2011-06-01

    The purpose of this study was to evaluate the effect of oil, surfactant/co-surfactant mixing ratios and water on the in vitro permeation of ketoconazole (KTZ) applied in O/W microemulsion vehicle through intact rat skin. Lauryl Alcohol (LA) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulsion system. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant (S) and ethanol (EtOH) as the cosurfactant (CoS). The formulation which showed a highest permeation rate of 54.65 ± 1.72 µg/cm(2)/h(1) and appropriate physico-chemical properties was optimized as containing 2% KTZ, 10% LA, 20% Lab/EtOH (1:1) and 68% double distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of KTZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of KTZ from microemulsions was enhanced with increasing the LA and water contents, and with decreasing the Lab/EtOH ratio in the formulation. Candida albicans was used as a model fungus to evaluate the antifungal activity of the best formula achieved, which showed the widest zone of inhibition as compared to KTZ reference. The studied microemulsion formulation showed a good stability for a period of three months. Histopathological investigation of rat skin revealed the safety of microemulsion formulations for topical use. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of KTZ. PMID:20146553

  20. High-temperature Hydrogen Permeation in Nickel Alloys

    SciTech Connect

    P. Calderoni; M. Ebner; R. Pawelko

    2010-10-01

    In gas cooled Very High Temperature Reactor concepts, tritium is produced as a tertiary fission product and by activation of graphite core contaminants, such as lithium; of the helium isotope, He-3, that is naturally present in the He gas coolant; and the boron in the B4C burnable poison. Because of its high mobility at the reactor outlet temperatures, tritium poses a risk of permeating through the walls of the intermediate heat exchanger (IHX) or steam generator (SG) systems, potentially contaminating the environment and in particular the hydrogen product when the reactor heat is utilized in connection with a hydrogen generation plant. An experiment to measure tritium permeation in structural materials at temperatures up to 1000 C has been constructed at the Idaho National Laboratory Safety and Tritium Applied Research (STAR) facility within the Next Generation Nuclear Plant program. The design is based on two counter flowing helium loops to represent heat exchanger conditions and was optimized to allow control of the materials surface condition and the investigation of the effects of thermal fatigue. In the ongoing campaign three nickel alloys are being considered because of their high-temperature creep properties, alloy 617, 800H and 230. This paper introduces the general issues related to tritium in the on-going assessment of gas cooled VHTR systems fission product transport and outlines the planned research activities in this area; outlines the features and capabilities of the experimental facility being operated at INL; presents and discusses the initial results of hydrogen permeability measurements in two of the selected alloys and compares them with the available database from previous studies.

  1. Tritium permeation considerations in the MARS direct convertor

    NASA Astrophysics Data System (ADS)

    Baskes, M. I.; Pontau, A. E.; Wilson, K. L.; Barr, W. L.

    1984-05-01

    The direct convertors located in the end cells of the MARS Tandem Mirror Fusion reactor recover the electrostatic energy of plasma particles that leak out of the center cell region. Since the direct convertors will be implanted in part by escaping high energy (> 40 keV) tritons at fluxes of over 10 16 T cm -2 s -1 and low energy (˜30 eV) tritons at fluxes of over 10 18 T cm -2 s -1, the possibility of tritium permeation into the water coolant, must be assessed. The current design calls for a TZM (Mo-0.5Ti-0.1Zr) structure; vanadium has also been under consideration. Combined nuclear reaction profiling and thermal desorption spectroscopy measurements on TZM show that deuterium retention is dominated by radiation damage traps with 1-1.5 eV detrapping energy, and bulk chemical traps of ≈ 0.7 eV presumably from the Ti and Zr alloying additions. Analysis of deuterium reemission data from vanadium demonstrates that molecular recombination controls the bulk retention. Values of the recombination constant for vanadium vary from 1.1 × 10 -22 cm 4 sec -1 at 500 °C to 3.6 × 10 -24 cm 4 sec -1 at 300 °C. Using these results and available literature data, calculations for Be on TZM, V, and V on Cu using DIFFUSE predict steady state permeation rates in excess of 10 8 Ci day -1 for bare V, 2000 Ci day -1 for Be on TZM, and ≈ 300 Ci day -1 for V on Cu.

  2. Membrane Permeation of a Peptide: It is Better to be Positive

    PubMed Central

    Cardenas, Alfredo E.; Shrestha, Rebika; Webb, Lauren J.; Elber, Ron

    2015-01-01

    A joint experimental and computational study investigates the translocation of a tryptophan molecule through a phospholipid membrane. Time dependent spectroscopy of the tryptophan side chain determines the rate of permeation into 150 nm phospholipid vesicles. Atomically detailed simulations are conducted to calculate the free energy profiles and the permeation coefficient. Different charging conditions of the peptide (positive, negative, or zwitterion) are considered. Both experiment and simulation reproduce the qualitative trend and suggest that the fastest permeation is when the tryptophan is positively charged. The permeation mechanism, which is revealed by Molecular Dynamics simulations, is of a translocation assisted by a local defect. The influence of long-range electrostatic interactions, such as the membrane dipole potential on the permeation process, is not significant. PMID:25941740

  3. The modeling of gas phase permeation through iron and nickel membranes

    NASA Technical Reports Server (NTRS)

    Kuhn, David K.; Shanabarger, Mickey R.

    1989-01-01

    The gas phase permeation of hydrogen through metal membranes encompasses many kinetic processes. This paper reviews a permeation model which incorporates second order gas-surface reaction kinetics with simple bulk diffusion. The model is used to investigate the effect of this particular surface reaction of steady-state permeation. The dependence of the steady-state permeation flux on temperature, pressure, and thickness of the membrane has been calculated. The model predicts that the bulk controlled steady-state flux will change to a surface limited steady-state flux as either the temperature or thickness of the membrane is reduced. Finally, using independently derived parameters, the model is compared with permeation measurements on iron and nickel membranes.

  4. Effect of formulation factors on in vitro transcorneal permeation of voriconazole from aqueous drops.

    PubMed

    Mohanty, Biswaranjan; Mishra, Sagar Kumar; Majumdar, Dipak K

    2013-10-01

    The purpose of this research was to evaluate the effect the formulation factors on in vitro permeation of voriconazole through freshly isolated goat and sheep corneas. An increase in the pH of the drops from 4.0 to 8.0 resulted in significant (P < 0.05) increase drug permeation. Raising concentration of the drops from 0.05% to 0.2% (w/v) significantly, (P < 0.05) increased drug permeation, but decreased the percent permeation. Corneal transport of voriconazole is both pH and concentration dependent. Eye drops containing disodium edetate (ethylenediaminetetraacetic acid) alone or combination with benzalkonium chloride showed significantly (P < 0.05) higher permeation as compared with control formulation. Addition of beta-cyclodextrin to the formulation enhanced corneal permeation of voriconazole. Compared with control formulation, voriconazole 0.2% (w/v) drop containing viscosity modifier produced significant (P < 0.05) decrease in permeation. Most of the formulations showed higher zone of inhibition against Candida albicans. PMID:24350052

  5. Behavior of tritium permeation induced by water corrosion of alpha iron around room temperature

    SciTech Connect

    Otsuka, T.; Hashizume, K.

    2015-03-15

    Tritium (T) permeation leakage to surroundings is a great safety concern in fission and fusion reactor systems. T permeation potentially occurs from T contaminated water through cooling tubes or storage tank made of metals which dissolve some T evolved by water corrosion. In order to understand behaviors of hydrogen uptake and permeation in pure α-iron (αFe) during water corrosion around room temperature, hydrogen permeation experiments for an αFe membrane have been conducted by means of tritium tracer techniques. The present study suggests that hydrogen produced by water corrosion of αFe is trapped in product oxide layers to delay hydrogen uptake in αFe for a moment. However, the oxide layers do not work as a sufficient barrier for hydrogen uptake. Some of hydrogen dissolved in αFe normally diffuses and permeates through the bulk in the early stage of permeation. In a later stage, hydrogen permeation could be apparently stopped by the disappearance of concentration difference of tritium. Hydrogen partial pressure at the water/αFe interface could be ranged from 0.7 to 9.5 kPa around room temperature.

  6. Effect of formulation factors on in vitro transcorneal permeation of voriconazole from aqueous drops

    PubMed Central

    Mohanty, Biswaranjan; Mishra, Sagar Kumar; Majumdar, Dipak K.

    2013-01-01

    The purpose of this research was to evaluate the effect the formulation factors on in vitro permeation of voriconazole through freshly isolated goat and sheep corneas. An increase in the pH of the drops from 4.0 to 8.0 resulted in significant (P < 0.05) increase drug permeation. Raising concentration of the drops from 0.05% to 0.2% (w/v) significantly, (P < 0.05) increased drug permeation, but decreased the percent permeation. Corneal transport of voriconazole is both pH and concentration dependent. Eye drops containing disodium edetate (ethylenediaminetetraacetic acid) alone or combination with benzalkonium chloride showed significantly (P < 0.05) higher permeation as compared with control formulation. Addition of beta-cyclodextrin to the formulation enhanced corneal permeation of voriconazole. Compared with control formulation, voriconazole 0.2% (w/v) drop containing viscosity modifier produced significant (P < 0.05) decrease in permeation. Most of the formulations showed higher zone of inhibition against Candida albicans. PMID:24350052

  7. Rapid permeation measurement system for the production control of monolayer and multilayer films

    NASA Astrophysics Data System (ADS)

    Botos, J.; Müller, K.; Heidemeyer, P.; Kretschmer, K.; Bastian, M.; Hochrein, T.

    2014-05-01

    Plastics have been used for packaging films for a long time. Until now the development of new formulations for film applications, including process optimization, has been a time-consuming and cost-intensive process for gases like oxygen (O2) or carbon dioxide (CO2). By using helium (He) the permeation measurement can be accelerated from hours or days to a few minutes. Therefore a manometric measuring system for tests according to ISO 15105-1 is coupled with a mass spectrometer to determine the helium flow rate and to calculate the helium permeation rate. Due to the accelerated determination the permeation quality of monolayer and multilayer films can be measured atline. Such a system can be used to predict for example the helium permeation rate of filled polymer films. Defined quality limits for the permeation rate can be specified as well as the prompt correction of process parameters if the results do not meet the specification. This method for process control was tested on a pilot line with a corotating twin-screw extruder for monolayer films. Selected process parameters were varied iteratively without changing the material formulation to obtain the best process parameter set and thus the lowest permeation rate. Beyond that the influence of different parameters on the helium permeation rate was examined on monolayer films. The results were evaluated conventional as well as with artificial neuronal networks in order to determine the non-linear correlation between all process parameters.

  8. Deuterium permeation through erbium oxide coatings on RAFM steels by a dip-coating technique

    NASA Astrophysics Data System (ADS)

    Chikada, Takumi; Naitoh, Shunya; Suzuki, Akihiro; Terai, Takayuki; Tanaka, Teruya; Muroga, Takeo

    2013-11-01

    A tritium permeation barrier is a promising solution for the problems of tritium loss and radiological safety in fusion blanket systems. In recent years, erbium oxide coatings have shown remarkable permeation reduction factors. One of the remaining issues for the coatings is the establishment of plant-scale fabrication. In this study, erbium oxide thin films have been fabricated by a dip-coating technique, which has the potential to coat a complex-shaped substrate, and deuterium permeation behavior in the coatings has been examined. Crack-free coatings were formed on a reduced activation ferritic/martensitic steel F82H substrate by use of a withdrawal speed of 1.0-1.4 mm s-1 and a heat-treatment process in hydrogen with moisture. In deuterium permeation experiments, a 0.2-μm-thick coating on both sides of the substrate showed a reduction factor of 600-700 in comparison with a F82H substrate below 873 K; however, the coating degraded at above 923 K because of crack formation. A double-coated sample indicated a reduction factor of up to 2000 and did not degrade at up to 923 K. The driving pressure dependence of the deuterium permeation flux indicated that the permeation tended to be limited by surface reactions at low temperatures. Optimization of the number of layers has the possibility to reduce degradation at high temperatures while maintaining high permeation reduction factors.

  9. Controlled permeation of cell membrane by single bubble acoustic cavitation.

    PubMed

    Zhou, Y; Yang, K; Cui, J; Ye, J Y; Deng, C X

    2012-01-10

    Sonoporation is the membrane disruption generated by ultrasound and has been exploited as a non-viral strategy for drug and gene delivery. Acoustic cavitation of microbubbles has been recognized to play an important role in sonoporation. However, due to the lack of adequate techniques for precise control of cavitation activities and real-time assessment of the resulting sub-micron process of sonoporation, limited knowledge has been available regarding the detail processes and correlation of cavitation with membrane disruption at the single cell level. In the current study, we developed a combined approach including optical, acoustical, and electrophysiological techniques to enable synchronized manipulation, imaging, and measurement of cavitation of single bubbles and the resulting cell membrane disruption in real-time. Using a self-focused femtosecond laser and high frequency ultrasound (7.44MHz) pulses, a single microbubble was generated and positioned at a desired distance from the membrane of a Xenopus oocyte. Cavitation of the bubble was achieved by applying a low frequency (1.5MHz) ultrasound pulse (duration 13.3 or 40μs) to induce bubble collapse. Disruption of the cell membrane was assessed by the increase in the transmembrane current (TMC) of the cell under voltage clamp. Simultaneous high-speed bright field imaging of cavitation and measurements of the TMC were obtained to correlate the ultrasound-generated bubble activities with the cell membrane poration. The change in membrane permeability was directly associated with the formation of a sub-micrometer pore from a local membrane rupture generated by bubble collapse or bubble compression depending on ultrasound amplitude and duration. The impact of the bubble collapse on membrane permeation decreased rapidly with increasing distance (D) between the bubble (diameter d) and the cell membrane. The effective range of cavitation impact on membrane poration was determined to be D/d=0.75. The maximum mean

  10. Changes in chemical permeation of disposable latex, nitrile, and vinyl gloves exposed to simulated movement.

    PubMed

    Phalen, Robert N; Le, Thi; Wong, Weng Kee

    2014-01-01

    Glove movement can affect chemical permeation of organic compounds through polymer glove products. However, conflicting reports make it difficult to compare the effects of movement on chemical permeation through commonly available glove types. The aim of this study was to evaluate the effect of movement on chemical permeation of an organic solvent through disposable latex, nitrile, and vinyl gloves. Simulated whole-glove permeation testing was conducted using ethyl alcohol and a previously designed permeation test system. With exposure to movement, a significant decrease (p ≤ 0.001) in breakthrough time (BT) was observed for the latex (-23%) and nitrile gloves (-31%). With exposure to movement, only the nitrile glove exhibited a significant increase (p ≤ 0.001) in steady-state permeation rate (+47%) and cumulative permeation at 30 min (+111%). Even though the nitrile glove provided optimum chemical resistance against ethyl alcohol, it was most affected by movement. With exposure to movement, the latex glove was an equivalent option for overall worker protection, because it was less affected by movement and the permeation rate was lower than that of the nitrile glove. In contrast, the vinyl glove was the least affected by movement, but did not provide adequate chemical resistance to ethyl alcohol in comparison with the nitrile and latex gloves. Glove selection should take movement and polymer type into account. Some glove polymer types are less affected by movement, most notably the latex glove in this test. With nitrile gloves, at least a factor of three should be used when attempting to assign a protection factor when repetitive hand motions are anticipated. Ultimately, the latex gloves outperformed nitrile and vinyl in these tests, which evaluated the effect of movement on chemical permeation. Future research should aim to resolve some of the observed discrepancies in test results with latex and vinyl gloves. PMID:24689368

  11. Changes in Chemical Permeation of Disposable Latex, Nitrile and Vinyl Gloves Exposed to Simulated Movement

    PubMed Central

    Phalen, Robert N.; Le, Thi; Wong, Weng Kee

    2014-01-01

    Glove movement can affect chemical permeation of organic compounds through polymer glove products. However, conflicting reports make it difficult to compare the effects of movement on chemical permeation through commonly available glove types. This study was aimed to evaluate the effect of movement on chemical permeation of an organic solvent through disposable latex, nitrile, and vinyl gloves. Simulated whole-glove permeation testing was conducted using ethyl alcohol and a previously designed permeation test system. With exposure to movement, a significant decrease (p ≤ 0.001) in breakthrough time was observed for the latex (-23%) and nitrile gloves (-31%). With exposure to movement, only the nitrile glove exhibited a significant increase (p ≤ 0.001) in steady-state permeation rate (+47%) and cumulative permeation at 30 min (+111%). Even though the nitrile glove provided optimum chemical resistance against ethyl alcohol, it was most affected by movement. With exposure to movement, the latex glove was an equivalent option for overall worker protection, because it was less affected by movement and the permeation rate was lower than that of the nitrile glove. In contrast, the vinyl glove was the least affected by movement, but did not provide adequate chemical resistance to ethyl alcohol in comparison with the nitrile and latex gloves. In conclusion, glove selection should take movement and polymer type into account. Some glove polymer types are less affected by movement, most notably the latex glove in this test. With nitrile gloves, at least a factor of three should be used when attempting to assign a protection factor when repetitive hand motions are anticipated. Ultimately, the latex gloves outperformed nitrile and vinyl in these tests, which evaluated the effect of movement on chemical permeation. Future research should aim to resolve some of the observed discrepancies in test results with latex and vinyl gloves. PMID:24689368

  12. Photoswitchable gas permeation membranes based on azobenzene-doped liquid crystals II. Permeation-switching characterization under variable volume and variable pressure conditions

    NASA Astrophysics Data System (ADS)

    Glowacki, E.; Hunt, K.; Abud, D.; Marshall, K. L.

    2010-08-01

    Stimuli-responsive gas permeation membranes hold substantial potential for industrial processes as well as in analytical and screening applications. Such "smart" membrane systems, although prevalent in liquid mass-transfer manipulations, have yet to be realized for gas applications. We report our progress in developing gas permeation membranes in which liquid crystalline (LC) phases afford the active region of permeation. To achieve rapid and reversible switching between LC and isotropic permeation states, we harnessed the photomechanical action of mesogenic azobenzene dyes that can produce isothermal nematic-isotropic transitions. Both polymeric and low-molecular-weight LC materials were tested. Three different dye-doped LC mixtures with mesogenic azo dyes were infused into commercially available track-etched porous membranes with regular cylindrical pores (0.4 to 10.0 μm). Photoinduced isothermal phase changes in the imbibed material produced large and fully reversible changes in the permeability of the membrane to nitrogen with 5 s of irradiation at 2 mW/cm2. Using two measurement tools constructed in-house, the permeability of the photoswitched membranes was determined by both variable-pressure and variable-volume methods. Both the LC and photogenerated isotropic states demonstrate a linear permeability/pressure (ideal sorption) relationship, with up to a 16-fold difference in their permeability coefficients. Liquid crystal compositions can be chosen such that the LC phase is more permeable than the isotropic-or vice versa. This approach is the first system offering reversible tunable gas permeation membranes.

  13. Investigation on the suitability of plasma sprayed Fe Cr Al coatings as tritium permeation barrier

    NASA Astrophysics Data System (ADS)

    Fazio, C.; Stein-Fechner, K.; Serra, E.; Glasbrenner, H.; Benamati, G.

    1999-08-01

    Results on the fabrication of a tritium permeation barrier by spraying Fe-Cr-Al powders are described. The sprayed coatings were deposited at temperatures below the Ac1 temperature of the ferritic-martensitic steel substrate and no post-deposition heat treatment was applied. The aim of the investigation was the determination of the efficiency of the coatings to act as tritium permeation barrier. Metallurgical investigations as well as hydrogen isotope permeation measurements were carried out onto the produced coatings. The depositions were performed on ferritic-martensitic steels by means of three types of spray techniques: high velocity oxy fuel, air plasma spray and vacuum plasma spray.

  14. Measurement by room-temperature phosphorescence of polynuclear aromatics containing hydrocarbon fuels that permeate glove materials

    SciTech Connect

    Gammage, R.B.; White, D.A.; Vo-Dinh, T.

    1986-01-01

    Permeations of commonly used glove materials by polynuclear aromatic (PNA) compounds in hydrocarbon fuels were measured with solid-state dosemeters composed of filter paper. The permeated PNA were sorbed by the filter paper and analyzed in situ using room-temperature phosphorescence spectroscopy. This technique provided a simple, cost-effective, and very sensitive means for measuring breakthrough times and permeation rates of the class of potentially carcinogenic PNA in liquid fuels derived from crude petroleum, oil shale, and coal. 7 refs., 3 figs.

  15. Interaction with Mixed Micelles in the Intestine Attenuates the Permeation Enhancing Potential of Alkyl-Maltosides.

    PubMed

    Gradauer, Kerstin; Nishiumi, Ayano; Unrinin, Kota; Higashino, Haruki; Kataoka, Makoto; Pedersen, Betty L; Buckley, Stephen T; Yamashita, Shinji

    2015-07-01

    The purpose of the present study was to investigate the interaction of intestinal permeation enhancers with lipid and surfactant components present in the milieu of the small intestine. Maltosides of different chain lengths (decyl-, dodecyl-, and tetradecyl-maltoside; DM, DDM, TDM, respectively) were used as examples of nonionic, surfactant-like permeation enhancers, and their effect on the permeation of FD4 across Caco-2 monolayers was monitored. To mimic the environment of the small intestine, modified versions of fasted and fed state simulated intestinal fluid (FaSSIFmod, FeSSIFmod6.5, respectively) were used in addition to standard transport media (TM). Compared to the buffer control, 0.5 mM DDM led to a 200-fold permeation enhancement of FD4 in TM. However, this was dramatically decreased in FaSSIFmod, where a concentration of 5 mM DDM was necessary in order to elicit a moderate, 4-fold, permeation enhancement. Its capacity to promote permeation was diminished further when FeSSIFmod6.5 was employed. Even when cells were exposed to a concentration of 5 mM, no significant permeation enhancement of FD4 was observed. Analogous effects were observed in the case of DM and TDM, with slight deviations on account of differences in their critical micelle concentration (CMC). This observation was corroborated by calculating the amount of maltoside monomer versus micellar bound maltoside in FaSSIFmod and FeSSIFmod6.5, which demonstrated a reduced amount of free monomer in these fluids. To evaluate the in vivo significance of our findings, DDM solutions in TM, FaSSIFmod, and FeSSIFmod6.5 were used for closed intestinal loop studies in rats. Consistent with the results found in in vitro permeation studies, these investigations illustrated the overwhelming impact of sodium taurocholate/lecithin micelles on the permeation enhancing effect of DDM. While DDM led to a 20-fold increase in FD4 bioavailability when it was applied in TM, no significant permeation enhancement was

  16. An automated in vitro dermal absorption procedure: I. Permeation of (14)C-labelled N,N-diethyl-m-toluamide through human skin and effects of short-wave ultraviolet radiation on permeation.

    PubMed

    Moody, R P; Martineau, P A

    1990-01-01

    An automated in vitro dermal absorption (AIDA) analysis procedure is reported together with a novel design for an AIDA cell chamber for measuring the permeation of pesticides through human skin and other membranes. Tests to determine the permeation of the insect repellent N,N-diethyl-m-toluamide (DEET) through fresh, frozen and heat-separated split-thickness human breast skin demonstrated permeation of 48.0 ± 10.18, 24.0 ± 7.76 and 42.4 ± 8.57% (mean ± SD), respectively, by 48 hr. permeation through nitrile butyl rubber glove material was not detected whereas 47.2 ± 3.16% permeation through a dialysis membrane was observed. Short-wave ultraviolet (UV) radiation had no significant effect on DEET permeation. The merits of AIDA in facilitating the precise simulation of environmental conditions during permeation testing are discussed. PMID:20837415

  17. Calcipotriol delivery into the skin as emulgel for effective permeation

    PubMed Central

    Naga Sravan Kumar Varma, V.; Maheshwari, P.V.; Navya, M.; Reddy, Sharath Chandra; Shivakumar, H.G.; Gowda, D.V.

    2014-01-01

    The objective of this work is to formulate and evaluate an emulgel containing calcipotriol for treatment of psoriasis. Emulgels have emerged as a promising drug delivery system for the delivery of hydrophobic drugs. Isopropyl alcohol and polyethylene glycol have been employed as permeation enhancers. Formulation chart is made with seven formulations, evaluated for physical parameters, drug content, viscosity, thixotropy, spreadability, extrudability, mucoadhesion, diffusion studies, skin irritation test along with short term stability studies. Carbopolis is reported to have a direct influence on appearance and viscosity of final formulation. The photomicroscopic evaluations showed the presence of spherical globules in size range of 10–15 μm. Rheograms revealed that all the formulations exhibited pseudoplastic flow. Optimized formulation (F6) had shown 86.42 ± 2.0% drug release at the end of 8 h study. The release rate through dialysis membrane and rat skin is higher when compared to commercial calcipotriol ointment. Hence it is concluded that calcipotriol can be delivered topically with enhanced penetration properties when formulated as emulgel. PMID:25561873

  18. Reactive oxygen species at phospholipid bilayers: distribution, mobility and permeation.

    PubMed

    Cordeiro, Rodrigo M

    2014-01-01

    Reactive oxygen species (ROS) are involved in biochemical processes such as redox signaling, aging, carcinogenesis and neurodegeneration. Although biomembranes are targets for reactive oxygen species attack, little is known about the role of their specific interactions. Here, molecular dynamics simulations were employed to determine the distribution, mobility and residence times of various reactive oxygen species at the membrane-water interface. Simulations showed that molecular oxygen (O2) accumulated at the membrane interior. The applicability of this result to singlet oxygen ((1)O2) was discussed. Conversely, superoxide (O2(-)) radicals and hydrogen peroxide (H2O2) remained at the aqueous phase. Both hydroxyl (HO) and hydroperoxyl (HO2) radicals were able to penetrate deep into the lipid headgroups region. Due to membrane fluidity and disorder, these radicals had access to potential peroxidation sites along the lipid hydrocarbon chains, without having to overcome the permeation free energy barrier. Strikingly, HO2 radicals were an order of magnitude more concentrated in the headgroups region than in water, implying a large shift in the acid-base equilibrium between HO2 and O2(-). In comparison with O2, both HO and HO2 radicals had lower lateral mobility at the membrane. Simulations revealed that there were intermittent interruptions in the H-bond network around the HO radicals at the headgroups region. This effect is expected to be unfavorable for the H-transfer mechanism involved in HO diffusion. The implications for lipid peroxidation and for the effectiveness of membrane antioxidants were evaluated. PMID:24095673

  19. Quantitative Analysis of the Enhanced Permeation and Retention (EPR) Effect

    PubMed Central

    Ulmschneider, Martin B.; Searson, Peter C.

    2015-01-01

    Tumor vasculature is characterized by a variety of abnormalities including irregular architecture, poor lymphatic drainage, and the upregulation of factors that increase the paracellular permeability. The increased permeability is important in mediating the uptake of an intravenously administered drug in a solid tumor and is known as the enhanced permeation and retention (EPR) effect. Studies in animal models have demonstrated a cut-off size of 500 nm - 1 µm for molecules or nanoparticles to extravasate into a tumor, however, surprisingly little is known about the kinetics of the EPR effect. Here we present a pharmacokinetic model to quantitatively assess the influence of the EPR effect on the uptake of a drug into a solid tumor. We use pharmacokinetic data for Doxil and doxorubicin from human clinical trials to illustrate how the EPR effect influences tumor uptake. This model provides a quantitative framework to guide preclinical trials of new chemotherapies and ultimately to develop design rules that can increase targeting efficiency and decrease unwanted side effects in normal tissue. PMID:25938565

  20. PEP Support: Laboratory Scale Leaching and Permeate Stability Tests

    SciTech Connect

    Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.; Buchmiller, William C.

    2010-05-21

    This report documents results from a variety of activities requested by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The activities related to caustic leaching, oxidative leaching, permeate precipitation behavior of waste as well as chromium (Cr) leaching are: • Model Input Boehmite Leaching Tests • Pretreatment Engineering Platform (PEP) Support Leaching Tests • PEP Parallel Leaching Tests • Precipitation Study Results • Cr Caustic and Oxidative Leaching Tests. Leaching test activities using the PEP simulant provided input to a boehmite dissolution model and determined the effect of temperature on mass loss during caustic leaching, the reaction rate constant for the boehmite dissolution, and the effect of aeration in enhancing the chromium dissolution during caustic leaching. Other tests were performed in parallel with the PEP tests to support the development of scaling factors for caustic and oxidative leaching. Another study determined if precipitate formed in the wash solution after the caustic leach in the PEP. Finally, the leaching characteristics of different chromium compounds under different conditions were examined to determine the best one to use in further testing.

  1. Permeation of oxygen through high purity, large grain silver

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Peregoy, W. K.; Hoflund, Gar B.

    1987-01-01

    The permeation of high purity, large grain Ag membranes by oxygen has been studied over the temperature range 400 to 800 C. The permeability was found to be quite linear and repeatable, but the magnitude was 3.2 times smaller than that determined by past research. Since previous investigators studied substantially less pure Ag and conducted experiments within much poorer vacuum environments (which indicates that their grain boundary density was much greater), the data presented here suggest oxygen transport through the membrane is primarily by grain boundary diffusion. The diffusivity measurements were found to exhibit two distinct linear regions, one above and one below a critical temperature of 630 C. The high-temperature data have an activation energy (11.1 kcal/mole) similar to that reported by others, but the low-temperature data have a higher activation energy (15.3 kcal/mole), which can be explained by impurity trapping in the grain boundaries. Vacuum desorption of the oxygen-saturated Ag was found to occur at a threshold of 630 C, which is consistent with the onset of increased mobility within the grain boundaries.

  2. Dynamics and energetics of water permeation through the aquaporin channel.

    PubMed

    Vidossich, Pietro; Cascella, Michele; Carloni, Paolo

    2004-06-01

    Structural properties of water inside bovine aquaporin-1 are investigated by molecular simulation. The calculations, which are based on the recently determined X-ray structure at 2.2 A resolution (Sui et al., Nature 2001;414:872-878), are carried out on one monomeric subunit immersed in a water-n-octane-water bilayer. Molecular dynamics (MD) simulations suggest that His182, a fully conserved residue in the channel pore, is protonated in the delta position. Furthermore, they reveal a highly ordered water structure in the channel, induced by the electrostatic properties of the protein. Multiple-steering MD simulations are used to calculate the free-energy of water diffusion. To the best of our knowledge, this represents the first free-energy calculation based on the new, high-resolution structure of the pore. The calculated barrier is 2.5 kcal/mol, and it is associated to water permeation through the Asn-Pro-Ala (NPA) region of the pore, where water molecules are only hydrogen-bonded with themselves. These findings are fully consistent with those based on the previous MD studies on the human protein (de Groot and Grubmüller, Science 2001;294:2353-2357). PMID:15146490

  3. Membrane Permeation Induced by Aggregates of Human Islet Amyloid Polypeptides

    PubMed Central

    Poojari, Chetan; Xiao, Dequan; Batista, Victor S.; Strodel, Birgit

    2013-01-01

    Several neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases as well as nonneuropathic diseases such as type II diabetes and atrial amyloidosis are associated with aggregation of amyloid polypeptides into fibrillar structures, or plaques. In this study, we use molecular dynamics simulations to test the stability and orientation of membrane-embedded aggregates of the human islet amyloid polypeptide (hIAPP) implicated in type II diabetes. We find that in both monolayers and bilayers of dipalmitoylphosphatidylglycerol (DPPG) hIAPP trimers and tetramers remain inside the membranes and preserve their β-sheet secondary structure. Lipid bilayer-inserted hIAPP trimers and tetramers orient inside DPPG at 60° relative to the membrane/water interface and lead to water permeation and Na+ intrusion, consistent with ion-toxicity in islet β-cells. In particular, hIAPP trimers form a water-filled β-sandwich that induce water permeability comparable with channel-forming proteins, such as aquaporins and gramicidin-A. The predicted disruptive orientation is consistent with the amphiphilic properties of the hIAPP aggregates and could be probed by chiral sum frequency generation (SFG) spectroscopy, as predicted by the simulated SFG spectra. PMID:24268144

  4. Permeation characteristics of some iron and nickel based alloys

    SciTech Connect

    Mitchell, D.J.; Edge, E.M.

    1985-06-15

    The permeation characteristics of deuterium in several iron and nickel based alloys were measured by the gas phase breakthrough technique in the temperature range 100 to 500 /sup 0/C with applied pressures ranging from 10 Pa to 100 kPa. The restriction of the gas flux imposed by surface oxides was modeled in order to evaluate the effects of surface oxide retardation of the gas flux on the effective values of the deuterium permeabilities and diffusivities in the alloys. The most permeable alloys were 430 and 431 stainless steels. The next most permeable alloy was Monel K-500, which exceeded the permeability of pure Ni by more than a factor of five at room temperature. The alloys with permeabilities less than pure Ni were, in order of decreasing permeability: the Inconels 625, 718, and 750, the Fe-Ni-Co glass-sealing alloys Kovar and Ceramvar, and the 300-series stainless steels. Deuterium trapping within the alloys appeared to influence the values of bulk diffusivities, which were not correlated with either the permeabilities or the chemical compositions of the alloys.

  5. Transdermal absorption of radioprotectors using permeation-enhancing vehicles

    SciTech Connect

    Sodicoff, M.; Lamperti, A.; Ziskin, M.C. )

    1990-02-01

    Radioprotectors are not currently used clinically due to concerns regarding toxicity and uncertainties regarding tumor protection. Topical radioprotection of skin might find clinical applications with protectors such as WR-2721, but laboratory studies in which protectors have been applied in water have not been promising. We have studied the absorption of 14C-WR-2721 and ({sup 14}C)cysteine dissolved in skin permeation-enhancing vehicles through the skin of hairless mice and compared the absorption to that in water. Skin concentration of WR-2721 was increased most by dimethylformamide (DMF), but only propylene glycol increased absorption as far as the dermis, as measured by plasma concentration. Skin concentration of cysteine was improved by DMF, 2-pyrrolidone (2-P), and methyl-2-pyrrolidone (M-2-P); only dimethylsulfoxide (DMSO) resulted in increased plasma levels of the protector. Pretreating skin with DMSO before application of WR-2721, irrespective of the vehicle, improved its concentration within the skin. Plasma levels were improved (10 and 12 times) only with 2-P and DMF. Therefore, by choosing the appropriate vehicle, it is possible to breach the barrier of the stratum corneum and enhance the presence of the protector in all layers of the skin.

  6. Drug permeation across intestinal epithelial cells using porous silicon nanoparticles.

    PubMed

    Bimbo, Luis M; Mäkilä, Ermei; Laaksonen, Timo; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2011-04-01

    Mesoporous silicon particles hold great potential in improving the solubility of otherwise poorly soluble drugs. To effectively translate this feature into the clinic, especially via oral or parenteral administration, a thorough understanding of the interactions of the micro- and nanosized material with the physiological environment during the delivery process is required. In the present study, the behaviour of thermally oxidized porous silicon particles of different sizes interacting with Caco-2 cells (both non-differentiated and polarized monolayers) was investigated in order to establish their fate in a model of intestinal epithelial cell barrier. Particle interactions and TNF-α were measured in RAW 264.7 macrophages, while cell viabilities, reactive oxygen species and nitric oxide levels, together with transmission electron microscope images of the polarized monolayers, were assessed with both the Caco-2 cells and RAW 264.7 macrophages. The results showed a concentration and size dependent influence on cell viability and ROS-, NO- and TNF-α levels. There was no evidence of the porous nanoparticles crossing the Caco-2 cell monolayers, yet increased permeation of the loaded poorly soluble drug, griseofulvin, was shown. PMID:21194747

  7. Comparison of chemical permeation data obtained with ASTM and ISO permeation test cells--II. The ISO/DIS standard test procedure.

    PubMed

    Mellström, G A

    1991-04-01

    ASTM and ISO/DIS test cells were used for permeation testing according to the procedure proposed in draft international standard ISO/DIS 6259. Two compounds, toluene and 1,1,1-trichloroethane, were tested with one neoprene glove and one made of a specially prepared Neoprene material. Different open-loop systems, direct-flow measurement and a sampling system with different gas flow rates were compared, and the effects on the test result were evaluated. The initial breakthrough (BTT) times and cumulative breakthrough times (lag-BTT) were significantly influenced only by the measurement systems. Neither cell configuration nor changes in the gas flow rate influenced them to any degree relevant for comparison of the test values on a relative basis in most cases. The permeation rates (PER) and the cumulative amount permeating per cm2 in 60 min showed significant differences between measuring systems, gas flow rates and the ASTM vs the ISO/DIS test procedures. PMID:2042883

  8. Alteration of skin hydration and its barrier function by vehicle and permeation enhancers: a study using TGA, FTIR, TEWL and drug permeation as markers.

    PubMed

    Shah, D K; Khandavilli, S; Panchagnula, R

    2008-09-01

    Vehicles and permeation enhancers (PEs) used in transdermal drug delivery (TDD) of a drug can affect skin hydration, integrity and permeation of the solute administered. This investigation was designed to study the effect of the most commonly used vehicles and PEs on rat skin hydration, barrier function and permeation of an amphiphilic drug, imipramine hydrochloride (IMH). An array of well-established techniques were used to confirm the findings of the study. Thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy were used to determine changes in skin hydration. Alteration of the stratum corneum (SC) structure was investigated using FTIR studies. To monitor the barrier function alteration, transepidermal water loss (TEWL) measurement and permeation studies were performed. Our findings indicate that with hydration, there was an increase in the bound water content of the skin, and pseudoequilibrium of hydration (a drastic decrease in hydration rate) was achieved at around 12 h. Hydration increased the ratio between amide-I and amide-II peaks in FTIR and reduced the C-H stretching peak area. Both propylene glycol (PG) and ethanol (EtOH) dehydrated skin, with the latter showing a predominant effect. Furthermore, it was confirmed that PG and EtOH decreased the bound water content due to alteration in the protein domains and extraction of SC lipids, respectively. The effect of hydration on the SC was found to be similar to that reported for temperature. Permeation studies revealed that the dehydration caused by vehicles decreased IMH flux, whereas the flux was enhanced by PEs. The role of partition was predominant for the permeation of IMH through dehydrated skin. A synergistic effect was observed for PG and menthol in the enhancement of IMH. Further findings provided strong evidence that PG affects protein domains and EtOH extracts lipids from the bilayer. Both PG and EtOH, with or without PEs, increased TEWL. Initial TEWL was well

  9. Mechanism of ion permeation through a model channel: roles of energetic and entropic contributions.

    PubMed

    Sumikama, Takashi; Saito, Shinji; Ohmine, Iwao

    2013-10-28

    Mechanism of ion permeation through an anion-doped carbon nanotube (ANT), a model of ion channel, is investigated. Using this model system, many trajectory calculations are performed to obtain the potential energy profile, in addition to the free energy profile, that enables to separate the energy and the entropic contributions, along the ion permeation. It is found that the mechanism of the transport is governed by the interplay between the energetic and the entropic forces. The rate of the ion permeation can be controlled by changing the balance between these contributions with altering, for example, the charge and/or the length of ANT, which increases the rate of the ion permeation by nearly two orders of magnitude. The dominant free energy barrier at the entrance of ANT is found to be caused by the entropy bottleneck due to the narrow phase space for the exchange of a water molecule and an incoming ion. PMID:24182087

  10. Potential Stable Low-Permeation Rate Standard Based on Micro-machined Silicon

    PubMed Central

    Verwolf, Adrian; Poling, Chris; Barbosa, Nick; White, Grady; Rentz, Nikki

    2015-01-01

    Silicon wafers with micro-machined holes were evaluated for use as low-permeation-rate standard artifacts. Accuracy, stability, and reliability were assessed. Two independent experimental techniques for evaluating permeation were used: chilled mirror hygrometer and mass loss. The wafers exhibited a well-defined linear relationship between hole area and resultant water partial pressure for both techniques, although the mass loss curve exhibited a constant vertical offset from the hygrometer curve, attributed to water loss through the O-ring seal. In contrast to polymer permeation standards, Si wafers provided long-term reproducible permeation rates. However, they were also highly fragile, with most of them cracking during the course of the investigation. PMID:26958454

  11. NOVEL CERAMIC-ORGANIC VAPOR PERMEATION MEMBRANES FOR VOC REMOVAL - PHASE I

    EPA Science Inventory

    Vapor permeation holds much promise for becoming a highly efficient means of preventing VOC emissions that are now generated by a variety of stationary sources, including solvent and surface coating operations, gasoline storage operations, and printing operations. A limitation of...

  12. A new method of measuring hydrogen diffusivity by hydrogen permeation technique . 1: Theoretical modeling

    SciTech Connect

    Zhang, T.Y.; Zheng, Y.P.

    1998-12-31

    A new model on hydrogen permeation is proposed, considering absorption and desorption processes on the sample surfaces. Analytical solution, satisfying the flux continuity rather than the concentration boundary conditions, is derived from the model. Drift velocity through surface and drift velocity in bulk are introduced and their ratio determines the validity of the time-lag model. When the ratio of drift velocity through surface over that in bulk approaches infinity, the proposed model is reduced to the time-lag one. The diffusivity and the drift velocity through surface can be evaluated by fitting the entire normalized permeation curve. The obtained results can predict the effects of temperature, sample thickness and energy barriers of absorption and desorption on the permeation process. The thickness effect occurred in using the time-lag model is well explained by the effects of absorption and desorption on the permeation process.

  13. Experimental Validation of Hybrid Distillation-Vapor Permeation Process for Energy Efficient Ethanol-Water Separation

    EPA Science Inventory

    The energy demand of distillation-based systems for ethanol recovery and dehydration can be significant, particularly for dilute solutions. An alternative separation process integrating vapor stripping with a vapor compression step and a vapor permeation membrane separation step...

  14. Experimental Validation of Hybrid Distillation-Vapor Permeation Process for Energy Efficient Ethanol-Water Separation

    EPA Science Inventory

    The energy demand of distillation-based systems for ethanol recovery and dehydration can be significant, particularly for dilute solutions. An alternative separation process integrating vapor stripping with a vapor compression step and a vapor permeation membrane separation step,...

  15. Pervaporation & Vapor Permeation Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures

    EPA Science Inventory

    Pervaporation and vapor permeation are membrane-based processes which have been proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol or butanol recovery from dilute fermentation broths, solvent/biofu...

  16. Pervaporation and Vapor Permeation Tutorial: Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures

    EPA Science Inventory

    Pervaporation and vapor permeation are membrane-based processes proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol or butanol recovery from fermentation broths, solvent/biofuel dehydration to meet ...

  17. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... requirements specified in 40 CFR 1051.110 or in this section. (4) Small SI fuel tanks must meet the permeation... follows: (1) Marine SI fuel tanks, including engine-mounted fuel tanks and portable marine fuel...

  18. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirements specified in 40 CFR 1051.110 or in this section. (4) Small SI fuel tanks must meet the permeation... follows: (1) Marine SI fuel tanks, including engine-mounted fuel tanks and portable marine fuel...

  19. New Conceptual Design of a Test Module Assembly for Tritium Permeation Experiment

    SciTech Connect

    O'hira, S.; Luo, G.-N.; Nakamura, H.; Shu, W.M.; Kitamura, K.; Nishi, M.

    2005-07-15

    A new conceptual design of a tritium permeation test module assembly was developed, for simulation of tritium permeation in the real plasma facing components and validation of the models and codes for evaluation of the tritium permeation. The assembly was designed for tests using powerful ion sources, which has a capability to simulate condition relevant to that of the ITER divertor. The heat load test of the prototype module has been performed using an electron beam to verify thermal and mechanical behavior of the bonded structure and to assess its structural integrity under the cyclic heat loads. Then, the first tests using tritium ion beam generated by the TPE apparatus at TSTA/LANL with the prototype module was performed and procedure to measure tritium permeated was established. Considerations for tests using the target module with defects generated by neutron irradiation or accelerated ion beam irradiation will be also taken in the new module design.

  20. Permeation behavior of deuterium implanted into Ti sbnd 6Al sbnd 4V alloy

    NASA Astrophysics Data System (ADS)

    Arita, M.; Hayashi, T.; Okuno, K.; Hayashi, Y.

    1997-09-01

    Permeation of deuterium implanted into Ti sbnd 6Al sbnd 4V alloy has been studied using 0.5 keV D + ion beam in the temperature range of 323 to 753 K. Above 600 K, the ratio of steady state permeation flux/incident flux ranges from 3.3 × 10 -3 at 633 K to 4.8 × 10 -3 at 753 K. The activation energy of permeation is about 0.12 eV in this temperature range. At temperatures below 600 K, the permeation flux of deuterium decreases drastically. Deuterium implanted in the lower temperature range desorbed from the alloy by heating after implantation. Thus, the most of the implanted ions remain in the alloy at low temperatures.

  1. NOVEL CERAMIC-ORGANIC VAPOR PERMEATION MEMBRANES FOR VOC REMOVAL - PHASE II

    EPA Science Inventory

    Vapor permeation with highly permeable and organic-selective membranes is becoming an increasingly popular technique for preventing VOC emissions that are generated by a variety of stationary sources, including solvent and surface coating operations, gasoline storage operat...

  2. Structure activity relationships in alkylammonium C12-gemini surfactants used as dermal permeation enhancers.

    PubMed

    Silva, Sérgio M C; Sousa, João J S; Marques, Eduardo F; Pais, Alberto A C C; Michniak-Kohn, Bozena B

    2013-10-01

    The purpose of this study was to determine the ability and the safety of a series of alkylammonium C12-gemini surfactants to act as permeation enhancers for three model drugs, namely lidocaine HCl, caffeine, and ketoprofen. In vitro permeation studies across dermatomed porcine skin were performed over 24 h, after pretreating the skin for 1 h with an enhancer solution 0.16 M dissolved in propylene glycol. The highest enhancement ratio (enhancement ratio (ER)=5.1) was obtained using G12-6-12, resulting in a cumulative amount of permeated lidocaine HCl of 156.5 μg cm−2. The studies with caffeine and ketoprofen revealed that the most effective gemini surfactant was the one with the shorter spacer, G12-2-12. The use of the latter resulted in an ER of 2.4 and 2.2 in the passive permeation of caffeine and ketoprofen, respectively. However, Azone was found to be the most effective permeation enhancer for ketoprofen, attaining a total of 138.4 μg cm−2 permeated, 2.7-fold over controls. This work demonstrates that gemini surfactants are effective in terms of increasing the permeation of drugs, especially in the case of hydrophilic ionized compounds, that do not easily cross the stratum corneum. Skin integrity evaluation studies did not indicate the existence of relevant changes in the skin structure after the use of the permeation enhancers, while the cytotoxicity studies allowed establishing a relative cytotoxicity profile including this class of compounds, single chain surfactants, and Azone. A dependence of the toxicity to HEK and to HDF cell lines on the spacer length of the various gemini molecules was found. PMID:23959685

  3. A moving robotic hand system for whole-glove permeation and penetration: captan and nitrile gloves.

    PubMed

    Phalen, Robert; Hee, Shane Que

    2008-04-01

    The aim of this study was to develop a robotic hand to test the influence of hand movement on the permeation/penetration of captan through disposable nitrile rubber gloves. An available robotic hand was modified to within one standard deviation of the anthropometric 50th percentile male hand. Permeation tests used a nylon inspection glove interposed between medium-size outer and inner nitrile gloves, the latter protected the hand. Permeation of an aqueous emulsion (217 mg/mL) of captan was conducted at 35 degrees C +/- 0.7 degrees C. A new surface wipe technique facilitated collection of captan from the inner surface of the exposed nitrile gloves, a technique favored above rinse methods that extracted captan from within the glove. With hand movement, the permeated mass of captan collected after 8 hr ranged from 1.6 to 970 microg (Brand A) and 8.6 +/- 1.2 microg (Brand B). Without hand movement, the corresponding masses ranged from 1.4 to 8.4 microg (Brand A) and 11 +/- 3 mg (Brand B). These results were not significantly different at p < or = 0.05 using parametric and nonparametric statistical tests but indicated that hand movement could influence the precision of permeation (F-test p < or = 0.05). One glove exhibited failure after 2 hr with movement, in comparison with 0.5 to 9.9 microg captan with no movement. Hand movement did not appear to significantly affect the permeation of captan through nitrile gloves. However, hand movement did influence physical and/or chemical degradation, resulting in glove failures. The robotic hand simulated normal hand motions, was reliable, and could be used to assess the influence of hand movement on the permeation of nonvolatile components through gloves. Future research should continue to investigate the influence of hand movement and additional work factors on the permeation, penetration, and physical integrity of protective gloves. PMID:18286423

  4. Permeation barrier coating and plasma sterilization of PET bottles and foils

    NASA Astrophysics Data System (ADS)

    Steves, Simon; Deilmann, Michael; Bibinov, Nikita; Awakowicz, Peter

    2009-10-01

    Modern packaging materials such as polyethylene terephthalate (PET) offer various advantages over glass or metal containers. Beside this they only offer poor barrier properties against gas permeation. Therefore, the shelf-live of packaged food is reduced. Additionally, common sterilization methods like heat, hydrogen peroxide or peracetic acid may not be applicable due to reduced heat or chemical resistance of the plastic packaging material. For the plasma sterilization and permeation barrier coating of PET bottles and foils, a microwave driven low pressure plasma reactor is developed based on a modified Plasmaline antenna. The dependencies of important plasma parameters, such as gas mixture, process pressure, power and pulse conditions on oxygen permeation through packaging foil are investigated. A residual permeation as low as J = 1.0 ±0.3 cm^3m-2day-1bar-1 for 60 nm thick silicon oxide (SiOx) coated PET foils is achieved. To discuss this residual permeation, coating defects are visualized by capacitively coupled atomic oxygen plasma etching of coated substrate. A defect density of 3000 mm-2 is revealed responsible for permeation. For plasma sterilization, optimized plasma parameters based on fundamental research of plasma sterilization mechanisms permit short treatment times of a few seconds.

  5. Inhibition effect of a non-permeating component on gas permeability of nanoporous graphene membranes.

    PubMed

    Wen, Boyao; Sun, Chengzhen; Bai, Bofeng

    2015-09-28

    We identify the inhibition effect of a non-permeating gas component on gases permeating through the nanoporous graphene membranes and reveal its mechanisms from molecular dynamics insights. The membrane separation process involves the gas mixtures of CH4/H2 and CH4/N2 with different partial pressures of the non-permeating gas component (CH4). The results show that the permeance of the H2 and N2 molecules decreases sharply in the presence of the CH4 molecules. The permeance of the N2 molecules can be reduced to as much as 64.5%. The adsorption of the CH4 molecules on the graphene surface weakens the surface adsorption of the H2 and N2 molecules due to a competitive mechanism, accordingly reducing the permeability of the H2 and N2 molecules. For the N2 molecules with stronger adsorption ability, the reduction of the permeance is greater. On the other hand, the CH4 molecules near the nanopore have a blocking effect, which further inhibits the permeation of the H2 and N2 molecules. In addition, we predict the selectivity of the nanopore by using density functional theory calculations. This work can provide valuable guidance for the application of nanoporous graphene membranes in the separation of the gas mixtures consisting of permeating and non-permeating components with different adsorption abilities. PMID:26299564

  6. Doxorubicin liposomes as an investigative model to study the skin permeation of nanocarriers.

    PubMed

    Boakye, Cedar H A; Patel, Ketan; Singh, Mandip

    2015-07-15

    The objectives of this study were to develop an innovative investigative model using doxorubicin as a fluorophore to evaluate the skin permeation of nanocarriers and the impact of size and surface characteristics on their permeability. Different doxorubicin-loaded liposomes with mean particle size <130 nm and different surface chemistry were prepared by ammonium acetate gradient method using DPPC, DOPE, Cholesterol, DSPE-PEG 2000 and 1,1-Di-((Z)-octadec-9-en-1-yl) pyrrolidin-1-ium chloride (CY5)/DOTAP/1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) as the charge modifier. There was minimal release of doxorubicin from the liposomes up to 8h; indicating that fluorescence observed within the skin layers was due to the intact liposomes. Liposomes with particle sizes >600 nm were restricted within the stratum corneum. DOTAP (p<0.01) and CY5 (p<0.05) liposomes demonstrated significant permeation into the skin than DOPA and PEG liposomes. Tape stripping significantly (p<0.01) enhanced the skin permeation of doxorubicin liposomes but TAT-decorated doxorubicin liposomes permeated better (p<0.005). Blockage of the hair follicles resulted in significant reduction in the extent and intensity of fluorescence observed within the skin layers. Overall, doxorubicin liposomes proved to be an ideal fluorophore-based model. The hair follicles were the major route utilized by the liposomes to permeate skin. Surface charge and particle size played vital roles in the extent of permeation. PMID:25910414

  7. Kinetics of Permeate Flux Decline in Crossflow Membrane Filtration of Colloidal Suspensions.

    PubMed

    Hong; Faibish; Elimelech

    1997-12-15

    A series of well-controlled membrane filtration experiments are performed to systematically investigate the dynamic behavior of permeate flux in crossflow membrane filtration of colloidal suspensions. Results are analyzed by a transient permeate flux model which includes an approximate closed-form analytical expression for the change of permeate flux with time. The model is based on a simplified particle mass balance for the early stages of crossflow filtration before a steady-state flux is attained, and Happel's cell model for the hydraulic resistance of the formed particle cake layer. The filtration experiments demonstrate that permeate flux declines faster with increasing feed particle concentration and transmembrane pressure and with a decrease in the particle size of the suspension. It is also shown that crossflow velocity (shear rate) has no effect on permeate flux at the transient stages of crossflow filtration. Pressure relaxation experiments indicate that the particle cake layer is reversible, implying no irreversible deposition (attachment) of particles onto the membrane surface or the accumulated (retained) particles. The experimental results are shown to be in very good agreement with the theoretical predictions, thus verifying the validity of the model for the transient permeate flux in crossflow filtration and the underlying assumptions in the derivation of the model. Copyright 1997 Academic Press. PMID:9792752

  8. Ionisation effects on the permeation of pharmaceutical compounds through silicone membrane.

    PubMed

    Waters, L J; Bhuiyan, A K M M H

    2016-05-01

    Silicone membrane is frequently used as an in vitro skin mimic whereby experiments incorporate a range of buffered media which may vary in pH. As a consequence of such variability in pH there is a corresponding variability in the degree of ionisation which in turn, could influence permeation through the mainly hydrophobic-rich membrane structure. This study reports the effect of pH on the permeation of five model compounds (benzoic acid, benzotriazole, ibuprofen, ketoprofen and lidocaine). For the five compounds analysed, each at three distinct percentages of ionisation, it was found that the greater extent of permeation was always for the more 'neutral', i.e. more greatly unionised, species rather than the anionic or cationic species. These findings fit with the theory that the hydrophobic membrane encourages permeation of 'lipid-like' structures, i.e. the more unionised form of compounds. However, results obtained with an Inverse Gas Chromatography Surface Energy Analyser (iGC SEA) indicate the membrane surface to be an electron dense environment. In the knowledge that unionised forms of compounds permeate (rather than the charged species) this negatively charged surface was not anticipated, i.e. the basic membrane surface did not appear to affect permeation. PMID:26896663

  9. In vitro permeation and in vivo whitening effect of topical hesperetin microemulsion delivery system.

    PubMed

    Tsai, Yi-Hung; Lee, Ko-Feng; Huang, Yaw-Bin; Huang, Chi-Te; Wu, Pao-Chu

    2010-03-30

    Hesperetin is one of the flavonoids and possess anti-inflammatory, UV-protecting and antioxidant effects. Permeation issues for topical delivery systems of such effects are occasionally problematic, and in view of the fact that microemulsions are potential carriers for transdermal delivery system, the objective of this study was to design an optimal microemulsion formulation by in vitro permeation study for hesperetin topical dosage form and determine its topical photoprotective effect and skin irritation by in vivo study. The hesperetin-loaded microemulsion showed an enhanced in vitro permeation compared to the aqueous and isopropyl myristate (IPM) suspension dosage form of hesperetin. In comparison, the effect of co-surfactant on the drug permeation capacity, propylene glycol showed highest permeation rate, followed by ethanol, glycerol and polyethylene glycol (PEG 400). Sunscreen agent padimate O, as a transdermal enhancer could increase the permeation rate of hesperetin. In case of in vivo study, the hesperetin-loaded microemulsion showed significant topical whitening effect and diminished skin irritation when compared with the non-treatment group, indicating that the hesperetin microemulsion could be used as an effective whitening agent. PMID:20060453

  10. EFFECT OF DIFFERENT ENHANCERS ON THE TRANSDERMAL PERMEATION OF INSLUIN ANALOG

    PubMed Central

    Yerramsetty, K. M.; Rachakonda, V. K.; Neely, B. J.; Madihally, S. V.; Gasem, K. A. M.

    2010-01-01

    Using chemical penetration enhancers (CPEs), transdermal drug delivery (TDD) offers an alternative route for insulin administration, wherein the CPEs reversibly reduce the barrier resistance of the skin. However, there is a lack of sufficient information concerning the effect of CPE chemical structure on insulin permeation. To address this limitation, we examined the effect of CPE functional groups on the permeation of insulin. A virtual design algorithm that incorporates quantitative structure-property relationship (QSPR) models for predicting the CPE properties was used to identify 43 potential CPEs. This set of CPEs was prescreened using a resistance technique, and the 22 best CPEs were selected. Next, standard permeation experiments in Franz cells were performed to quantify insulin permeation. Our results indicate that specific functional groups are not directly responsible for enhanced insulin permeation. Rather, permeation enhancement is produced by molecules that exhibit positive log Kow values and possess at least one hydrogen donor or acceptor. Toluene was the only exception among the 22 potential CPEs considered. In addition, toxicity analyses of the 22 CPEs were performed. A total of eight CPEs were both highly enhancing (permeability coefficient at least four times the control value) and non-toxic, five of which are new discoveries. PMID:20667506

  11. Evaluation of the transdermal permeation of different paraben combinations through a pig ear skin model.

    PubMed

    Caon, Thiago; Costa, Ana Carolina Oliveira; de Oliveira, Marcone Augusto Leal; Micke, Gustavo Amadeu; Simões, Cláudia Maria Oliveira

    2010-05-31

    Although parabens have several features of ideal preservatives, different studies have shown that they may affect human health due to their estrogenic activity. Therefore, various strategies have been applied to reduce their skin penetration. However, the effect of paraben combinations on transdermal permeation has not yet been investigated. Thus, the objective of this study was to evaluate paraben permeation in pig ear skin using a Franz diffusion cell system with capillary electrophoresis detection, in order to identify which paraben combinations (defined by a factorial design) have the lowest skin permeation. The permeation of isolated parabens was also evaluated and the permeation characteristics, obtained by the Moser model, confirmed that lipophilicity and molecular weight may influence the systemic absorption of these compounds. In previous tests using isolated parabens, methyl and ethyl parabens presented greater retention in the epidermis compared to the dermis, while propyl and butyl parabens had similar retention profiles in these layers. An increase in ethanol concentration and experimental time promoted greater parabens retention in the dermis compared to the epidermis. The binary combinations of methyl and ethyl parabens as well as of methyl and propyl parabens (added to several cosmetic products in order to increase the antimicrobial spectrum) reduced significantly their permeation rates through pig ear skin (with the exception of EP), probably due to the high retention of these parabens in the epidermis and dermis. PMID:20156540

  12. Enhanced skin permeation of naltrexone by pulsed electromagnetic fields in human skin in vitro.

    PubMed

    Krishnan, Gayathri; Edwards, Jeffrey; Chen, Yan; Benson, Heather A E

    2010-06-01

    The aim of the present study was to evaluate the skin permeation of naltrexone (NTX) under the influence of a pulsed electromagnetic field (PEMF). The permeation of NTX across human epidermis and a silicone membrane in vitro was monitored during and after application of the PEMF and compared to passive application. Enhancement ratios of NTX human epidermis permeation by PEMF over passive diffusion, calculated based on the AUC of cumulative NTX permeation to the receptor compartment verses time for 0-4 h, 4-8 h, and over the entire experiment (0-8 h) were 6.52, 5.25, and 5.66, respectively. Observation of the curve indicated an initial enhancement of NTX permeation compared to passive delivery whilst the PEMF was active (0-4 h). This was followed by a secondary phase after termination of PEMF energy (4-8 h) in which there was a steady increase in NTX permeation. No significant enhancement of NTX penetration across silicone membrane occurred with PEMF application in comparison to passively applied NTX. In a preliminary experiment PEMF enhanced the penetration of 10 nm gold nanoparticles through the stratum corneum as visualized by multiphoton microscopy. This suggests that the channels through which the nanoparticles move must be larger than the 10 nm diameter of these rigid particles. PMID:20014281

  13. Permeation of a straight oil metalworking fluid through a disposable and a chemically protective nitrile glove.

    PubMed

    Xu, Wenhai; Que Hee, Shane S

    2006-09-21

    The aim of the present study was to quantify the permeation parameters of a complex water-insoluble straight oil metalworking fluid (MWF) of low volatility through nitrile gloves. The permeation through a chemically protective and a disposable glove was investigated using the American Society for Testing and Materials (ASTM) F739-99a method with hexane as the collection medium. Analysis of collection side samples involved gas chromatography-mass spectrometry (GC-MS) and gravimetry. The detection breakthrough time for the chemically protective glove was >10 h. For the disposable glove, the detection breakthrough time was 0.7+/-0.3 h, the lag time was 1.6+/-0.1 h, the diffusion coefficient was (3.7+/-0.3)x10(-9) cm2/min, and the steady state permeation rate was 3.5+/-2.2 microg/cm2/min. The disposable nitrile glove can be worn for about 30 min for incidental contact with straight oil MWFs without known carcinogens. The chemically protective nitrile glove should be worn otherwise. The chromatogram for the permeate differed from that of the original MWF, resulting from the faster permeation of lower molecular weight congeners. The combination of chromatography and gravimetry allowed quantifying the permeation parameters of complex water-insoluble non-volatile mixtures. PMID:16650529

  14. Permeation of a straight oil metalworking fluid through disposable nitrile, chloroprene, vinyl, and latex gloves.

    PubMed

    Xu, Wenhai; Que Hee, Shane S

    2007-08-25

    The aim was to investigate the permeation of a straight oil metalworking fluid (MWF) through four types of glove materials using the gravimetric method and the modified American Society for Testing and Materials (ASTM) F739-99a method with perfluorohexane and hexane as collection solvents. The residual masses on the collection side were determined after solvent evaporation for both MWF and blank (air) challenges. With perfluorohexane, the permeated MWF through gloves after 8h was around the lower quantifiable limit for nitrile, 0.7+/-0.2mg/cm(2) for vinyl, 10.0+/-1.2mg/cm(2) for chloroprene, and 33.0+/-0.7mg/cm(2) for latex. Hexane increased the amounts and rates of MWF permeating all gloves 39-73 times, except for vinyl where extractable mass was so high that the residues for MWF challenges and for hexane blanks were indistinguishable. Hexane as a collection solvent also extracted more glove components than did perfluorohexane, and back-permeated gloves in much larger amounts. Perfluorohexane allows better estimates of the real permeation rates and breakthrough times than does hexane. Recommendations based on breakthrough times and permeation rates with hexane collection are thus too conservative, although the relative ranking of these four types of gloves was the same with either collection solvent. PMID:17324502

  15. Study on hydrogen isotopes permeation in fluidized state of liquid lithium-lead

    SciTech Connect

    Yoshimura, S.; Yoshimura, R.; Okada, M.; Fukada, S.; Edao, Y.

    2015-03-15

    Lithium-lead (Li-Pb) is one of the most promising candidate materials for the liquid blanket of fusion reactors. Hydrogen transfer under a fluidized condition of Li-Pb is investigated experimentally to design a Li-Pb blanket system. Li-Pb eutectic alloy flows inside a Ni tube in the experimental system, where H{sub 2} permeates into and out of the forced Li-Pb flow. The overall H{sub 2} permeation rate is analyzed using a mass balance model. Hydrogen atoms diffuse in Ni and Li-Pb. The steady-state H{sub 2} permeation rate obtained by this experiment is smaller than the result of the calculation model. A resistance factor is introduced to the present analysis in order to evaluate the influence of other H{sub 2} transfer mechanisms, such as diffusion in Li-Pb and dissolution reaction between Ni and Li-Pb. The contribution of the resistance to the overall H{sub 2} permeation rate becomes large when the flow rate of Li-Pb is low. This is because the boundary layer thickness between Ni and Li-Pb affects the overall H{sub 2} permeation rate. When the flow velocity of Li-Pb increases, the thickness of the boundary layer becomes thin, and the driving force of H{sub 2} permeation through the Ni wall becomes bigger. (authors)

  16. Scoping Analyses on Tritium Permeation to VHTR Integarted Industrial Application Systems

    SciTech Connect

    Chang H. Oh; Eung S. Kim

    2011-03-01

    Tritium permeation is a very important current issue in the very high temperature reactor (VHTR) because tritium is easily permeated through high temperature metallic surfaces. Tritium permeations in the VHTR-integrated systems were investigated in this study using the tritium permeation analysis code (TPAC) that was developed by Idaho National Laboratory (INL). The INL TPAC is a numerical tool that is based on the mass balance equations of tritium containing species and hydrogen (i.e. HT, H2, HTO, HTSO4, TI) coupled with a variety of tritium sources, sink, and permeation models. In the TPAC, ternary fission and thermal neutron caption reactions with 6Li, 7Li 10B, 3He were taken into considerations as tritium sources. Purification and leakage models were implemented as main tritium sinks. Permeation of tritium and H2 through pipes, vessels, and heat exchangers were considered as main tritium transport paths. In addition, electroyzer and isotope exchange models were developed for analyzing hydrogen production systems including high temperature electrolysis (HTSE) and sulfur-iodine processes.

  17. Inorganic particles increase biofilm heterogeneity and enhance permeate flux.

    PubMed

    Chomiak, A; Sinnet, B; Derlon, N; Morgenroth, E

    2014-11-01

    This study investigated the influence of inorganic particles on the hydraulic resistance of biofilm grown on membrane surface during low-pressure dead-end ultrafiltration. Gravity-driven ultrafiltration membrane systems were operated during several weeks without any flushing or cleaning. Smaller (kaolin d0.5 = 3.6 μm) or larger (kaolin with diatomaceous earth 50/50%, d0.5 = 18.1 μm) particles were added to pre-filtered creek water or to unfiltered creek water. It was demonstrated in both experiments that presence of finer particles in the feed water (kaolin) induced formation of compact and homogeneous biofilm structure. On the other hand presence of the larger particles (diatomite) helped to counterbalance the effect of fine particles due to the formation of more heterogeneous and permeable biofilm structure. The hydraulic resistance of biofilms formed with fine particles was significantly higher than the resistance of biofilm formed in (1) absence of any inorganic particles or (2) in presence of the mixed particle population. The membrane orientation (vertical or horizontal) determined which particles were accumulating at the membrane surface, with structural differences shown by Scanning Electron Microscopy (SEM). For vertical membranes, the larger particles were selectively removed due to sedimentation and did not contribute to the biofilm development. Thus the selection of smaller particles due to vertical membrane configuration negatively affected the biofilm structure and permeation rates, and such selective accumulation of fine particles should be avoided. PMID:25058736

  18. Human skin permeation of emerging mycotoxins (beauvericin and enniatins).

    PubMed

    Taevernier, Lien; Veryser, Lieselotte; Roche, Nathalie; Peremans, Kathelijne; Burvenich, Christian; Delesalle, Catherine; De Spiegeleer, Bart

    2016-05-01

    Currently, dermal exposure data of cyclic depsipeptide mycotoxins are completely absent. There is a lack of understanding about the local skin and systemic kinetics and effects, despite their widespread skin contact and intrinsic hazard. Therefore, we provide a quantitative characterisation of their dermal kinetics. The emerging mycotoxins enniatins (ENNs) and beauvericin (BEA) were used as model compounds and their transdermal kinetics were quantitatively evaluated, using intact and damaged human skin in an in vitro Franz diffusion cell set-up and ultra high-performance liquid chromatography (UHPLC)-MS analytics. We demonstrated that all investigated mycotoxins are able to penetrate through the skin. ENN B showed the highest permeation (kp,v=9.44 × 10(-6) cm/h), whereas BEA showed the lowest (kp,v=2.35 × 10(-6) cm/h) and the other ENNs ranging in between. Combining these values with experimentally determined solubility data, Jmax values ranging from 0.02 to 0.35 μg/(cm(2) h) for intact skin and from 0.07 to 1.11 μg/(cm(2) h) for damaged skin were obtained. These were used to determine the daily dermal exposure (DDE) in a worst-case scenario. On the other hand, DDE's for a typical occupational scenario were calculated based on real-life mycotoxin concentrations for the industrial exposure of food-related workers. In the latter case, for contact with intact human skin, DDE's up to 0.0870 ng/(kg BW × day) for ENN A were calculated, whereas for impaired skin barrier this can even rise up to 0.3209 ng/(kg BW × day) for ENN B1. This knowledge is needed for the risk assessment after skin exposure of contaminated food, feed, indoor surfaces and airborne particles with mycotoxins. PMID:25757886

  19. A permeation theory for single-file ion channels: One- and two-step models

    NASA Astrophysics Data System (ADS)

    Nelson, Peter Hugo

    2011-04-01

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  20. Regional intestinal drug permeation: biopharmaceutics and drug development.

    PubMed

    Lennernäs, Hans

    2014-06-16

    Over the last 25 years, profound changes have been seen in both the development and regulation of pharmaceutical dosage forms, due primarily to the extensive use of the biopharmaceutical classification system (BCS) in both academia and industry. The BCS and the FDA scale-up and post-approval change guidelines were both developed during the 1990s and both are currently widely used to claim biowaivers. The development of the BCS and its wide acceptance were important steps in pharmaceutical science that contributed to the more rational development of oral dosage forms. The effective permeation (Peff) of drugs through the intestine often depends on the combined outcomes of passive diffusion and multiple parallel transport processes. Site-specific jejunal Peff cannot reflect the permeability of the whole intestinal tract, since this varies along the length of the intestine, but is a useful approximation of the fraction of the oral dose that is absorbed. It appears that drugs with a jejunal Peff>1.5×10(-4)cm/s will be completely absorbed no matter which transport mechanisms are utilized. In this paper, historical clinical data originating from earlier open, single-pass perfusion studies have been used to calculate the Peff of different substances from sites in the jejunum and ileum. More exploratory in vivo studies are required in order to obtain reliable data on regional intestinal drug absorption. The development of experimental and theoretical methods of assessing drug absorption from both small intestine and various sites in the colon is encouraged. Some of the existing human in vivo data are discussed in relation to commonly used cell culture models. It is crucial to accurately determine the input parameters, such as the regional intestinal Peff, as these will form the basis for the expected increase in modeling and simulation of all the processes involved in GI drug absorption, thus facilitating successful pharmaceutical development in the future. It is suggested

  1. Transdermal permeation of Kaempferia parviflora methoxyflavones from isopropyl myristate-based vehicles.

    PubMed

    Tuntiyasawasdikul, Sarunya; Limpongsa, Ekapol; Jaipakdee, Napaphak; Sripanidkulchai, Bungorn

    2014-08-01

    Kaempferia parviflora (K. parviflora) rhizomes have long been used in traditional folk medicines and as general health-promoting agents. Several biological activities of K. parviflora, especially its anti-inflammatory effect, are due to its major constituents, methoxyflavones. However, the oral bioavailability of these methoxyflavones has been shown to be low. The aim of this study was to investigate the permeation behaviors of K. parviflora methoxyflavones from isopropyl myristate (IPM)-based vehicles. We studied the effects of ethanol and propylene glycol (PG) as the hydrophilic, solvent-type vehicles as well as fatty acids as the permeation enhancers. A permeation experiment was performed in vitro, using side-by-side diffusion cells through the full thickness of pig ear skin. The solubility and permeation of methoxyflavones were able to be modified by choice and ratio of vehicles. The ethanol/IPM vehicle was shown to be more effective in enhancing the solubility and permeation of methoxyflavones when compared to the PG/IPM vehicle. Regarding an optimal balance between solubility or affinity to vehicle and skin to vehicle partition coefficient, the ethanol/IPM vehicle in the ratio of 1:9 maximized the flux. Among the investigated fatty acids, oleic acid showed the greatest enhancing effect on the permeation of methoxyflavones, indicating that saturated fatty acids are less effective than unsaturated fatty acids. Long chain fatty acids increased diffusion coefficient parameter and shortened the lag time. The number of carbon atoms and double bonds of fatty acids did not show direct relation to the profile of permeation of methoxyflavones. PMID:24789664

  2. High Pressure Gas Permeation and Liquid Diffusion Studies of Coflon and Tefzel Thermoplastics. Revision

    NASA Technical Reports Server (NTRS)

    Morgan, G. J.; Campion, R. P.

    1997-01-01

    The life of fluid-carrying flexible or umbilical pipes during service at elevated temperatures and pressures depends inter alia on their resistance to attack by the fluids present and the rate at which these fluids are absorbed by the pipe lining materials. The consequences of fluid ingress into the thermoplastic lining could mean a) a reduction in its mechanical strength, to increase chances of crack formation and growth and thus a loss of integrity, b) the occurrence of permeation right through the lining material, with pressure build- up in the outer pipe wall construction (of flexible pipes) or chemical attack (from a hostile permeant) on outer layers of reinforcements. Therefore it is important within this project to have relevant permeation data for Coflon and Tefzel thermoplastics: the former is plasticised, the latter is not. A previous report (CAPP/M.2) described experimental equipment and techniques used by MERL when measuring high pressure (up to 5000 psi) gas permeation and liquid diffusion through thermoplastic samples cut from extruded bar or pipe, and provided the basic theory involved. Norsk Hydro are also performing gas permeation tests on pipe sections, at up to 100 bars (1450 psi) pressure or so, and reporting separately. Some comparisons between data from Norsk Hydro and MERL have been made herein. The tests should be considered as complementary, as the Norsk Hydro test has the obvious benefit of using complete pipe sections, whilst MERL can test at much higher pressures, up to 1000 bar if necessary. The sophisticated analytical measuring equipment of Norsk Hydro can distinguish the individual components of mixed gases and hence the various permeation-linked coefficients whereas MERL, in using pressure increase at constant volume to determine permeation rate, is limited to obtaining single gas data, or apparent (or representative) coefficients for a mixed gas as a whole. Except for the initial fluid diffusion data for Tefzel described in CAPP

  3. Protective gloves of polymeric materials. Experimental permeation testing and clinical study of side effects.

    PubMed

    Mellström, G

    1991-01-01

    In the occupational use and handling of hazardous chemicals and infectious materials, exposure must be minimized. To diminish the risk of direct skin contact and percutaneous toxicity, the use of protective gloves is one of the most important measures to consider. For effective protection, the selection process must include evaluation of permeation test data as well as the risk of side effects possibly caused by the glove materials. In permeation testing (in vitro), breakthrough time and permeation rate are key values measured. Test conditions such as size and design of the permeation test cell, flow rate of the collecting medium through the test cell, measurement systems, testing procedures and analytical equipment can vary and can have crucial influence on the test results. In the present investigation, five permeation test cells of different sizes and design were used, the collecting gas flow rate was varied between 60 and 120 ml/min and 120 to 500 ml/min, the ASTM F 739 and ISO/DIS standard test procedures were performed using two different measurement systems, and in vitro versus in vivo testing techniques were studied. Gloves and glove materials of neoprene were exposed to four organic solvents. The breakthrough times (in vitro) for the test chemicals were slightly influenced by variations in cell size and design, flow rate and test procedure. The only significant influence on the breakthrough time values was between the two measurement systems, direct flow and automatic sampling. On the other hand, the permeation rate values were affected to a much greater extent, in most cases significantly. The test conditions in the in vitro and in vivo procedures differed in many ways and the test results were therefore compared on a relative basis. The breakthrough time values for the solvents through gloves of vinyl, natural rubber and butyl rubber were in the same rank order in both in vitro and in vivo testing. There was no evident correlation between the relative

  4. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition

    NASA Astrophysics Data System (ADS)

    Li Tong, Wei; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K.; Mun Hung, Yew

    2015-06-01

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications.

  5. Counter-Permeation of Deuterium and Hydrogen Through INCONEL 600[reg

    SciTech Connect

    Takeda, Tetsuaki; Iwatsuki, Jin

    2004-04-15

    Permeation of hydrogen isotopes through a high-temperature alloy used for heat exchanger and catalyst pipes is an important problem in the hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR). The objective of this study is to investigate the effect of the existence of hydrogen in an outside pipe on the amount of permeated deuterium through the pipe. It was found that the amount of permeated deuterium decreases by increasing the partial pressure of hydrogen in the outside pipe when the partial pressure of deuterium in the pipe is lower than 100 Pa and that of hydrogen in the outside pipe is larger than 10 kPa. The amount of permeated deuterium on counter permeation was predicted quantitatively by using an effectiveness factor for diffusivity of deuterium in metals and by taking into account the equilibrium state for hydrogen, deuterium, and HD molecules on the metal surface. From the results obtained in this study, it is supposed that the amount of tritium transferred from the primary circuit of the HTTR to the hydrogen production system will be reduced by the existence of high-pressure hydrogen in the catalyst pipe of the steam reformer.

  6. Impact of Humidity on In Vitro Human Skin Permeation Experiments for Predicting In Vivo Permeability.

    PubMed

    Ishida, Masahiro; Takeuchi, Hiroyuki; Endo, Hiromi; Yamaguchi, Jun-Ichi

    2015-12-01

    In vitro skin permeation studies have been commonly conducted to predict in vivo permeability for the development of transdermal therapeutic systems (TTSs). We clarified the impact of humidity on in vitro human skin permeation of two TTSs having different breathability and then elucidated the predictability of in vivo permeability based on in vitro experimental data. Nicotinell(®) TTS(®) 20 and Frandol(®) tape 40mg were used as model TTSs in this study. The in vitro human skin permeation experiments were conducted under humidity levels similar to those used in clinical trials (approximately 50%) as well as under higher humidity levels (approximately 95%). The skin permeability values of drugs at 95% humidity were higher than those at 50% humidity. The time profiles of the human plasma concentrations after TTS application fitted well with the clinical data when predicted based on the in vitro permeation parameters at 50% humidity. On the other hand, those profiles predicted based on the parameters at 95% humidity were overestimated. The impact of humidity was higher for the more breathable TTS; Frandol(®) tape 40mg. These results show that in vitro human skin permeation experiments should be investigated under realistic clinical humidity levels especially for breathable TTSs. PMID:26461468

  7. Vehicle effects on in vitro release and skin permeation of octylmethoxycinnamate from microemulsions.

    PubMed

    Montenegro, L; Carbone, C; Puglisi, G

    2011-02-28

    The high content of surfactants is one of the major limits to microemulsions (MEs) use in pharmaceutical and cosmetic field. In this work MEs with low surfactant content were prepared by the phase inversion temperature (PIT) method using different oil phases and emulsifiers. The effects of vehicle composition on in vitro release and skin permeation of octylmethoxycinnamte (OMC), one of the most used UVB filter, was evaluated. These MEs showed droplet sizes in the range 32-77nm and a single peak in size distribution. MEs prepared using the most lipophilic lipids (decyl oleate or cetyl stearyl isononanoate) showed the lowest stability. In vitro release and skin permeation profiles were affected by both lipophilicty and structure of the lipid used as internal phase and the formulation that released the lowest amount of OMC provided the lowest active compound skin permeation. It is noteworthy that no OMC release and skin permeation were observed using oleth-20/glyceryl oleate as emulsifiers. Furthermore, a skin permeation enhancement effect was observed depending on the vehicle components. The results of this work suggest that PIT MEs could provide controlled skin drug delivery by choosing proper associations of oil phase lipids and emulsifiers. PMID:21129459

  8. Surface-functionalized nanoparticle permeation triggers lipid displacement and water and ion leakage.

    PubMed

    Oroskar, Priyanka A; Jameson, Cynthia J; Murad, Sohail

    2015-01-27

    Functionalized nanoparticles (NPs) are considered suitable carriers for targeted drug delivery systems. However, the ion and water leakage induced by permeation of these nanoparticles is a challenge in these drug delivery methods because of cytotoxic effects of some ions. In this study, we have carried out a series of coarse-grained molecular dynamics simulations to investigate the effect of length of ligands on permeation of a nanoparticle across a protein-free phospholipid bilayer membrane. Water and ion penetration as well as incidence of lipid flip-flop events and loss of lipid molecules from the membrane are explored in this study while varying the nanoparticle size, length of ligand, ion concentration gradient, pressure differential across the membrane, and nanoparticle permeation velocity. Some results from our studies include (1) the number of water molecules in the interior of the membrane during ligand-coated nanoparticle permeation increases with nanoparticle size, ligand length, pressure differential, and permeation velocity but is not sensitive to the ion concentration gradient; (2) some lipid molecules leave the membrane by being entangled with ligands of the NP instead of completing the flip-flop that permits them to rejoin the membrane, thereby leading to fewer flip-flop events; and (3) the formation of water columns or water "fingers" provides a mechanism of ion transport across lipid bilayer membranes, but such ion penetration events are less likely for sodium ions than chloride ions and less likely for nanoparticles with longer-ligands. PMID:25549137

  9. Liposomal buccal mucoadhesive film for improved delivery and permeation of water-soluble vitamins.

    PubMed

    Abd El Azim, Heba; Nafee, Noha; Ramadan, Alyaa; Khalafallah, Nawal

    2015-07-01

    This study aims at improving the buccal delivery of vitamin B6 (VB6) as a model highly water-soluble, low permeable vitamin. Two main strategies were combined; first VB6 was entrapped in liposomes, which were then formulated as mucoadhesive film. Both plain and VB6-loaded liposomes (LPs) containing Lipoid S100 and propylene glycol (∼ 200 nm) were then incorporated into mucoadhesive film composed of SCMC and HPMC. Results showed prolonged release of VB6 (72.65%, T50% diss 105 min) after 6h from LP-film compared to control film containing free VB6 (96.37%, T50% diss 30 min). Mucoadhesion was assessed both ex vivo on chicken pouch and in vivo in human. Mucoadhesive force of 0.2N and residence time of 4.4h were recorded. Ex vivo permeation of VB6, across chicken pouch mucosa indicated increased permeation from LP-systems compared to corresponding controls. Interestingly, incorporation of the vesicles in mucoadhesive film reduced the flux by 36.89% relative to LP-dispersion. Meanwhile, both films provided faster initial permeation than the liquid forms. Correlating the cumulative percent permeated ex vivo with the cumulative percent released in vitro indicated that LPs retarded VB6 release but improved permeation. These promising results represent a step forward in the field of buccal delivery of water-soluble vitamins. PMID:25899288

  10. Tritium permeation in EUROFER97 steel in EXOTIC-9/1 irradiation experiment

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Magielsen, A. J.; Stijkel, M. P.

    2014-05-01

    This paper presents the results of the tritium permeation study in EUROFER97 carried out within the EXOTIC (EXtraction Of Tritium In Ceramics) irradiation experiment. In the EXOTIC 9/1 experiment, a pebble bed assembly containing Lithium Titanate (Li2TiO3) pebbles is irradiated for 300 days in the High Flux Reactor (HFR), in the temperature range between 340 and 580 °C, reaching a lithium burn up of 3.5% and 1.2 dpa of damage in steel. The primary objective of this experiment was to measure the in-pile tritium release characteristics of Li2TiO3 pebbles. Additionally tritium permeation through the EUROFER97 pebble bed wall was measured on line. The permeation of tritium was studied at steady state conditions, during temperature transients, and at different hydrogen concentrations in the helium purge gas flow. The model used in the analysis of the experimental data which account for co-permeation of tritium and hydrogen is presented. It has been demonstrated that the permeation of tritium under experiment conditions proceeds in the diffusion limited regime. From the analysis of the experimental data the permeability and diffusivity of tritium in EUROFER97 is determined.

  11. A method to visualize transdermal nickel permeation in mouse skin using a nickel allergy patch

    PubMed Central

    Sugiyama, Tomoko; Uo, Motohiro; Wada, Takahiro; Hongo, Toshio; Omagari, Daisuke; Komiyama, Kazuo; Oikawa, Masakazu; Kusama, Mikio; Mori, Yoshiyuki

    2015-01-01

    Metal patch test is often used in clinical settings when metal-induced contact dermatitis is suspected. However, the transdermal permeation behavior of metal ions from the patch test remains unclear. Current patch tests using high concentrations of metal salt solutions have some side effects, e.g. acute skin reactions to high concentrations of metal salt. To resolve these, estimating metal ion transdermal permeation is wished. In this study, synchrotron radiation X-ray fluorescence (SR-XRF) and micro-focused particle-induced X-ray emission (micro-PIXE) were used to visualize the time-dependent Ni permeation in mouse skin. The cross-sectional diffusion of Ni was visualized in a time-dependent manner. Our results indicate that maximum Ni permeation occurs after 24 h of patch treatment, and the permeated Ni content was high in the epidermis and spread into the dermis beyond the basal layer. This method may be useful to determine the appropriate solution concentration and duration of administration for the patch test. PMID:26484550

  12. Hydrolysis of lactose in whey permeate for subsequent fermentation to ethanol.

    PubMed

    Coté, A; Brown, W A; Cameron, D; van Walsum, G P

    2004-06-01

    Fermentation of lactose in whey permeate directly into ethanol has had only limited commercial success, as the yields and alcohol tolerances of the organisms capable of directly fermenting lactose are low. This study proposes an alternative strategy: treat the permeate with acid to liberate monomeric sugars that are readily fermented into ethanol. We identified optimum hydrolysis conditions that yield mostly monomeric sugars and limit formation of fermentation inhibitors such as hydroxymethyl furfural by caramelization reactions. Both lactose solutions and commercial whey permeates were hydrolyzed using inorganic acids and carbonic acid. In all cases, more glucose was consumed by secondary reactions than galactose. Galactose was recovered in approximately stoichiometric proportions. Whey permeate has substantial buffering capacity-even at high partial pressures (>5500 kPa[g]), carbon dioxide had little effect on the pH in whey permeate solutions. The elevated temperatures required for hydrolysis with CO2-generated inhibitory compounds through caramelization reactions. For these reasons, carbon dioxide was not a feasible acidulant. With mineral acids reversion reactions dominated, resulting in a stable amount of glucose released. However, the Maillard browning reactions also appeared to be involved. By applying Hammet's acidity function, kinetic data from all experiments were described by a single line. With concentrated inorganic acids, low reaction temperatures allowed lactose hydrolysis with minimal by-product formation and generated a hexose-rich solution amenable to fermentation. PMID:15453474

  13. Shed king cobra and cobra skins as model membranes for in-vitro nicotine permeation studies.

    PubMed

    Pongjanyakul, Thaned; Prakongpan, Sompol; Panomsuk, Suwannee; Puttipipatkhachorn, Satit; Priprem, Aroonsri

    2002-10-01

    Shed king cobra skin (SKCS) and shed cobra skin (SCS) were investigated for use as barrier membranes, including some pre-hydration factors, for in-vitro nicotine permeation. Inter-specimen variations in nicotine fluxes using shed snake skin were compared with those using human epidermis. Nicotine in the form of 1% w/v aqueous buffer solution at pH 5 and transdermal patches (dose 14 mg day(-1)) were used. The nicotine fluxes across the shed snake skin were not significantly affected (P > 0.05) by temperature and duration of hydration pre-treatment. Scanning electron micrographs of SKCS and SCS revealed a remarkable difference in surface morphology, but the nicotine fluxes using both shed skins were not significantly different (P > 0.05). When compared with the results obtained using human epidermis, there were similarities in fluxes and permeation profiles of nicotine. Using nicotine solution, the nicotine permeation profiles of all membranes followed zero order kinetics. The amount of nicotine permeated provided good linearity with the square root of time over 24 h (R(2) > 0.98) when using nicotine patches. The nicotine fluxes using SKCS and SCS had less inter-specimen variation than those using human epidermis. The results suggest a potential use for SKCS or SCS as barrier membranes for in-vitro nicotine permeation studies. PMID:12396295

  14. A model to predict the permeation kinetics of dimethyl sulfoxide in articular cartilage.

    PubMed

    Yu, Xiaoyi; Chen, Guangming; Zhang, Shaozhi

    2013-02-01

    Cryopreservation of articular cartilage (AC) has excited great interest due to the practical surgical importance of this tissue. Characterization of permeation kinetics of cryoprotective agents (CPA) in AC is important for designing optimal CPA addition/removal protocols to achieve successful cryopreservation. Permeation is predominantly a mass diffusion process. Since the diffusivity is a function of temperature and concentration, analysis of the permeation problem would be greatly facilitated if a predictive method were available. This article describes, a model that was developed to predict the permeation kinetics of dimethyl sulfoxide (DMSO) in AC. The cartilage was assumed as a porous medium, and the effect(s) of composition and thermodynamic nonideality of the DMSO solution were considered in model development. The diffusion coefficient was correlated to the infinite dilution coefficients through a binary diffusion thermodynamic model. The UNIFAC model was used to evaluate the activity coefficient, the Vignes equation was employed to estimate the composition dependence of the diffusion coefficient, and the Siddiqi-Lucas correlation was applied to determine the diffusion coefficients at infinite dilution. Comparisons of the predicted overall DMSO uptake by AC with the experimental data over wide temperature and concentration ranges [1~37°C, 10~47% (w/w)] show that the model can accurately describe the permeation kinetics of DMSO in AC [coefficient of determination (R(2)): 0.961~0.996, mean relative error (MRE): 2.2~9.1%]. PMID:24845255

  15. Test conditions greatly influence permeation of water soluble molecules through the intestinal mucosa: need for standardisation.

    PubMed Central

    Peeters, M; Hiele, M; Ghoos, Y; Huysmans, V; Geboes, K; Vantrappen, G; Rutgeerts, P

    1994-01-01

    Permeability tests are widely used to investigate the pathogenesis of various gastrointestinal diseases including coeliac disease, infectious diarrhoea, and inflammatory bowel disease. In Crohn's disease they are used as activity parameters by some investigators. Lack of standardisation, however, makes it very difficult to compare data reported in different studies. The aim of this study was to gather permeation data in well controlled test conditions to standardise the methods. Nine healthy volunteers each received five consecutive permeability tests by mouth using polyethylene glycol-400 (PEG-400) and 51Cr-EDTA as probe molecules. The probes were dissolved in water, a glucose solution, a starch solution, a hyperosmolar lactulose-mannitol solution, and a liquid meal. A significantly decreased permeation for both probes was found when given with the hyperosmolar solution. The 51Cr-EDTA permeation was also decreased with water. The permeability index, 51Cr-EDTA/PEG-400, corrected for influencing factors, confirmed that the lactulose-mannitol solution and plain water yield lower values of macro-molecule permeation than starch, glucose or liquid meal. Hyperosmolarity was clearly accompanied by a decrease in permeability probably caused by reversed solvent drag. Interindividual variability of probe permeation and permeability index is very low with a standard liquid meal. It is proposed that for permeability studies a standard liquid meal is always used. PMID:7959195

  16. Test conditions greatly influence permeation of water soluble molecules through the intestinal mucosa: need for standardisation.

    PubMed

    Peeters, M; Hiele, M; Ghoos, Y; Huysmans, V; Geboes, K; Vantrappen, G; Rutgeerts, P

    1994-10-01

    Permeability tests are widely used to investigate the pathogenesis of various gastrointestinal diseases including coeliac disease, infectious diarrhoea, and inflammatory bowel disease. In Crohn's disease they are used as activity parameters by some investigators. Lack of standardisation, however, makes it very difficult to compare data reported in different studies. The aim of this study was to gather permeation data in well controlled test conditions to standardise the methods. Nine healthy volunteers each received five consecutive permeability tests by mouth using polyethylene glycol-400 (PEG-400) and 51Cr-EDTA as probe molecules. The probes were dissolved in water, a glucose solution, a starch solution, a hyperosmolar lactulose-mannitol solution, and a liquid meal. A significantly decreased permeation for both probes was found when given with the hyperosmolar solution. The 51Cr-EDTA permeation was also decreased with water. The permeability index, 51Cr-EDTA/PEG-400, corrected for influencing factors, confirmed that the lactulose-mannitol solution and plain water yield lower values of macro-molecule permeation than starch, glucose or liquid meal. Hyperosmolarity was clearly accompanied by a decrease in permeability probably caused by reversed solvent drag. Interindividual variability of probe permeation and permeability index is very low with a standard liquid meal. It is proposed that for permeability studies a standard liquid meal is always used. PMID:7959195

  17. Permeation of halide anions through phospholipid bilayers occurs by the solubility-diffusion mechanism

    NASA Technical Reports Server (NTRS)

    Paula, S.; Volkov, A. G.; Deamer, D. W.

    1998-01-01

    Two alternative mechanisms are frequently used to describe ionic permeation of lipid bilayers. In the first, ions partition into the hydrophobic phase and then diffuse across (the solubility-diffusion mechanism). The second mechanism assumes that ions traverse the bilayer through transient hydrophilic defects caused by thermal fluctuations (the pore mechanism). The theoretical predictions made by both models were tested for halide anions by measuring the permeability coefficients for chloride, bromide, and iodide as a function of bilayer thickness, ionic radius, and sign of charge. To vary the bilayer thickness systematically, liposomes were prepared from monounsaturated phosphatidylcholines (PC) with chain lengths between 16 and 24 carbon atoms. The fluorescent dye MQAE (N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide) served as an indicator for halide concentration inside the liposomes and was used to follow the kinetics of halide flux across the bilayer membranes. The observed permeability coefficients ranged from 10(-9) to 10(-7) cm/s and increased as the bilayer thickness was reduced. Bromide was found to permeate approximately six times faster than chloride through bilayers of identical thickness, and iodide permeated three to four times faster than bromide. The dependence of the halide permeability coefficients on bilayer thickness and on ionic size were consistent with permeation of hydrated ions by a solubility-diffusion mechanism rather than through transient pores. Halide permeation therefore differs from that of a monovalent cation such as potassium, which has been accounted for by a combination of the two mechanisms depending on bilayer thickness.

  18. Assessment of diclofenac permeation with different formulations: anti-inflammatory study of a selected formula.

    PubMed

    Escribano, Elvira; Calpena, Ana Cristina; Queralt, Josep; Obach, Rossend; Doménech, Jose

    2003-07-01

    The aim of this study was to improve the transdermal permeation of sodium diclofenac. Permeation studies were carried out in vitro using human skin (0.4 mm thick) from plastic surgery as a membrane. Four liquid formulations of 1% (w/w) sodium diclofenac were assayed: three ternary solvent systems (M4, M5, M6) and one microemulsion (M3). A 1% (w/w) solution of sodium diclofenac and a commercially available semisolid preparation were tested as reference formulations. The following permeation parameters for diclofenac were assessed: permeability coefficient, flux and drug permeated and retained in the skin at 24 h. The highest values of these parameters were obtained with formula M4, which contains transcutol 59.2%, oleic acid 14.9% and d-limonene 5% (w/w) as permeation enhancers. The anti-inflammatory activity of this formula was compared with that of the semisolid preparation on carrageenan-induced paw edema in rats. As expected from in vitro results, the M4 diclofenac delivery system showed higher activity than the semisolid preparation, both when applied locally (to the inflammation area) and when applied systemically (to the back). Neither treatment irritated the skin when tested on rabbits in a 72-h trial. These results suggest that topical delivery of sodium diclofenac with an absorption enhancer such as a mixture of oleic acid and d-limonene (M4) may be an effective medication for both dermal and subdermal injuries. PMID:12885384

  19. Comparison of implantation-driven permeation characteristics of fusion reactor structural materials

    SciTech Connect

    Longhurst, G.R.; Anderl, R.A.; Struttmann, D.A.

    1986-04-04

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D/sub 3//sup +/ ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation ''spike'' followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Ion-beam sputtering of the surface in the steel experiments resulted in enhanced remission at the front surface, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. This may be due to a phase change in the material. We conclude that for conditions comparable to those of these experiments, tritium retention and loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti.

  20. Determination of solvents permeating through chemical protective clothing with a microsensor array.

    PubMed

    Park, J; Zellers, E T

    2000-08-01

    The performance of a novel prototype instrument in determining solvents and solvent mixtures permeating through samples of chemical protective clothing (CPC) materials was evaluated. The instrument contains a mini-preconcentrator and an array of three polymer-coated surface-acoustic-wave (SAW) microsensors whose collective response patterns are used to discriminate among multiple permeants. Permeation tests were performed with a 2.54 cm diameter test cell in an open-loop configuration on samples of common glove materials challenged with four individual solvents, three binary mixtures, and two ternary mixtures. Breakthrough times, defined as the times required for the permeation rate to reach a value of 1 microg cm(-2) min(-1), determined by the instrument were within 3 min of those determined in parallel by manual sampling and gas chromatographic analysis. Permeating solvents were recognized (identified) from their response patterns in 59 out of 64 measurements (92%) and their vapor concentrations were quantified to an accuracy of +/- 31% (typically +/- 10%). These results demonstrate the potential for such instrumentation to provide semi-automated field or bench-top screening of CPC permeation resistance. PMID:11249783

  1. Skin permeation of organic gunshot residue: implications for sampling and analysis.

    PubMed

    Moran, Jordan Wade; Bell, Suzanne

    2014-06-17

    Traditional gunshot residue (GSR) analysis is based on detection of particulates formed from metals found in the primer. Recent concerns regarding the interpretation of GSR evidence has led to interest in alternatives such as the organic constituents (organic gunshot residue, OGSR) found in propellants. Previous work has shown OGSR to be detectable on hands for several hours after a firing event, and given the lipophilic nature of these compounds, it was expected that losses due to secondary transfer (an issue with GSR particulates) would be negligible. However, other loss mechanisms have been identified, specifically skin permeation and evaporation. This paper describes experimental and modeling studies used to elucidate characteristics of skin permeation of 5 compounds present in OGSR. Pharmaceutical methods were adapted to characterize skin permeation using a skin surrogate and Franz diffusion cells. The amount of compounds deposited on skin after an authentic firing event (1 and 2 shots) was experimentally determined and applied for the permeation experiments. A fully validated selected ion monitoring GC/MS method was developed for quantitative analysis, and easily accessible online tools were employed for modeling. Results showed that OGSR residues should be detectable on skin for many hours after a firing event of as few as one or two shots, with detection capability being a function of the efficacy of sampling and sample preparation and the instrumental method employed. The permeation rates of the OGSR compounds were sufficiently different to suggest the potential to develop methods to approximate time-since-deposition. PMID:24837230

  2. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition

    PubMed Central

    Li Tong, Wei; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K.; Mun Hung, Yew

    2015-01-01

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications. PMID:26100977

  3. Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition.

    PubMed

    Tong, Wei Li; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K; Hung, Yew Mun

    2015-01-01

    The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications. PMID:26100977

  4. A method to visualize transdermal nickel permeation in mouse skin using a nickel allergy patch.

    PubMed

    Sugiyama, Tomoko; Uo, Motohiro; Wada, Takahiro; Hongo, Toshio; Omagari, Daisuke; Komiyama, Kazuo; Oikawa, Masakazu; Kusama, Mikio; Mori, Yoshiyuki

    2015-01-01

    Metal patch test is often used in clinical settings when metal-induced contact dermatitis is suspected. However, the transdermal permeation behavior of metal ions from the patch test remains unclear. Current patch tests using high concentrations of metal salt solutions have some side effects, e.g. acute skin reactions to high concentrations of metal salt. To resolve these, estimating metal ion transdermal permeation is wished. In this study, synchrotron radiation X-ray fluorescence (SR-XRF) and micro-focused particle-induced X-ray emission (micro-PIXE) were used to visualize the time-dependent Ni permeation in mouse skin. The cross-sectional diffusion of Ni was visualized in a time-dependent manner. Our results indicate that maximum Ni permeation occurs after 24 h of patch treatment, and the permeated Ni content was high in the epidermis and spread into the dermis beyond the basal layer. This method may be useful to determine the appropriate solution concentration and duration of administration for the patch test. PMID:26484550

  5. Tritium recovery from Li17 sbnd Pb83 liquid breeder by permeation window method

    NASA Astrophysics Data System (ADS)

    Terai, T.; Suzuki, A.; Tanaka, S.

    1997-09-01

    The tritium permeation window method was demonstrated by out-pile deuterium permeation experiments. The deuterium permeation rate was measured at changing parameters such as the chemical composition of purge gas, the fluidity of Li17 sbnd Pb83, the temperature and the condition of surface oxide film to clarify the rate-determining process. The overall mass-transfer coefficient of deuterium from Li17 sbnd Pb83 to purge gas through the Nb wall was smaller by 2-5 orders in magnitude than that determined by deuterium diffusion in Nb. This is not due to deuterium diffusion in Li17 sbnd Pb83 liquid film but due to the formation of niobium oxides on the surface as a permeation barrier. The permeation rate severely decreased with the growth of surface oxide film and it became too small for an actual blanket system. Therefore, it is necessary to protect the Nb surface from oxidation or to use nobler metals instead of Nb.

  6. Simulation Studies of Ion Permeation and Selectivity in Voltage-Gated Sodium Channels.

    PubMed

    Ing, C; Pomès, R

    2016-01-01

    Voltage-gated ion channels are responsible for the generation and propagation of action potentials in electrically excitable cells. Molecular dynamics simulations have become a useful tool to study the molecular basis of ion transport in atomistic models of voltage-gated ion channels. The elucidation of several three-dimensional structures of bacterial voltage-gated sodium channels (Nav) in 2011 and 2012 opened the way to detailed computational investigations of this important class of membrane proteins. Here we review the numerous simulation studies of Na(+) permeation and selectivity in bacterial Nav channels published in the past 5years. These studies use a variety of simulation methodologies differing in force field parameters, molecular models, sampling algorithms, and simulation times. Although results disagree on the details of ion permeation mechanisms, they concur in the presence of two primary Na(+) binding sites in the selectivity filter and support a loosely coupled knock-on mechanism of Na(+) permeation. Comparative studies of Na(+), K(+), and Ca(2+) permeation reveal sites within Nav channels that are Na(+) selective, yet a consensus model of selectivity has not been established. We discuss the agreement between simulation and experimental results and propose strategies that may be used to resolve discrepancies between simulation studies in order to improve future computational studies of permeation and selectivity in ion channels. PMID:27586286

  7. Effect of permeation enhancers in the mucoadhesive buccal patches of salbutamol sulphate for unidirectional buccal drug delivery

    PubMed Central

    Prasanth, V.V.; Puratchikody, A.; Mathew, S.T.; Ashok, K.B.

    2014-01-01

    The purpose of this work was to study the effect of various permeation enhancers on the permeation of salbutamol sulphate (SS) buccal patches through buccal mucosa in order to improve the bioavailability by avoiding the first pass metabolism in the liver and possibly in the gut wall and also achieve a better therapeutic effect. The influence of various permeation enhancers, such as dimethyl sulfoxide (DMSO), linoleic acid (LA), isopropyl myristate (IPM) and oleic acid (OA) on the buccal absorption of SS from buccal patches containing different polymeric combinations such as hydroxypropyl methyl cellulose (HPMC), carbopol, polyvinyl alcohol (PVA), polyvinyl pyrollidone (PVP), sodium carboxymethyl cellulose (NaCMC), acid and water soluble chitosan (CHAS and CHWS) and Eudragit-L100 (EU-L100) was investigated. OA was the most efficient permeation enhancer increasing the flux greater than 8-fold compared with patches without permeation enhancer in HPMC based buccal patches when PEG-400 was used as the plasticizer. LA also exhibited a better permeation enhancing effect of over 4-fold in PVA and HPMC based buccal patches. In PVA based patches, both OA and LA were almost equally effective in improving the SS permeation irrespective of the plasticizer used. DMSO was more effective as a permeation enhancer in HPMC based patches when PG was the plasticizer. IPM showed maximum permeation enhancement of greater than 2-fold when PG was the plasticizer in HPMC based buccal patches. PMID:25657797

  8. Effect of permeation enhancers in the mucoadhesive buccal patches of salbutamol sulphate for unidirectional buccal drug delivery.

    PubMed

    Prasanth, V V; Puratchikody, A; Mathew, S T; Ashok, K B

    2014-01-01

    The purpose of this work was to study the effect of various permeation enhancers on the permeation of salbutamol sulphate (SS) buccal patches through buccal mucosa in order to improve the bioavailability by avoiding the first pass metabolism in the liver and possibly in the gut wall and also achieve a better therapeutic effect. The influence of various permeation enhancers, such as dimethyl sulfoxide (DMSO), linoleic acid (LA), isopropyl myristate (IPM) and oleic acid (OA) on the buccal absorption of SS from buccal patches containing different polymeric combinations such as hydroxypropyl methyl cellulose (HPMC), carbopol, polyvinyl alcohol (PVA), polyvinyl pyrollidone (PVP), sodium carboxymethyl cellulose (NaCMC), acid and water soluble chitosan (CHAS and CHWS) and Eudragit-L100 (EU-L100) was investigated. OA was the most efficient permeation enhancer increasing the flux greater than 8-fold compared with patches without permeation enhancer in HPMC based buccal patches when PEG-400 was used as the plasticizer. LA also exhibited a better permeation enhancing effect of over 4-fold in PVA and HPMC based buccal patches. In PVA based patches, both OA and LA were almost equally effective in improving the SS permeation irrespective of the plasticizer used. DMSO was more effective as a permeation enhancer in HPMC based patches when PG was the plasticizer. IPM showed maximum permeation enhancement of greater than 2-fold when PG was the plasticizer in HPMC based buccal patches. PMID:25657797

  9. Peculiarities of hydrogen permeation through Zr-1%Nb alloy and evaluation of terminal solid solubility

    NASA Astrophysics Data System (ADS)

    Denisov, E. A.; Kompaniets, M. V.; Kompaniets, T. N.; Bobkova, I. S.

    2016-04-01

    Hydrogen permeation through Zr-1%Nb alloy was studied at the temperature below the temperature of α-β transition. Analysis of the transient permeation curves from a closed volume in a surface limited regime allowed to determine total and mobile hydrogen concentrations. At the mobile hydrogen concentration of 4.3 at% a part of the absorbed hydrogen is cut out of permeation process. Increase of the mobile hydrogen concentration in α-phase of Zr-1%Nb alloy is ceasing at the concentration of (5.5 ± 0.3) at%, which is the maximum possible concentration of the mobile hydrogen in α-phase of the studied alloy. From this moment on all absorbed hydrogen is spent on hydride formation. The obtained results are compared with those obtained by means of traditional techniques for terminal solid solubility determination.

  10. Tritium permeation characterization of materials for fusion and generation IV very high temperature reactors

    SciTech Connect

    Thomson, S.; Pilatzke, K.; McCrimmon, K.; Castillo, I.; Suppiah, S.

    2015-03-15

    The objective of this work is to establish the tritium-permeation properties of structural alloys considered for Fusion systems and very high temperature reactors (VHTR). A description of the work performed to set up an apparatus to measure permeation rates of hydrogen and tritium in 304L stainless steel is presented. Following successful commissioning with hydrogen, the test apparatus was commissioned with tritium. Commissioning tests with tritium suggest the need for a reduction step that is capable of removing the oxide layer from the test sample surfaces before accurate tritium-permeation data can be obtained. Work is also on-going to clearly establish the temperature profile of the sample to correctly estimate the tritium-permeability data.

  11. Enhanced permeation of single-file water molecules across a noncylindrical nanochannel

    NASA Astrophysics Data System (ADS)

    Meng, X. W.; Huang, J. P.

    2013-07-01

    We utilize molecular dynamics simulations to study the effect of noncylindrical shapes of a nanochannel (which are inspired from the shape of real biological water nanochannels) on the permeation of single-file water molecules across the nanochannel. Compared with the cylindrical shape that has been tremendously adopted in the literature, the noncylindrical shapes play a crucial role in enhancing water permeation. Remarkably, the maximal enhancement ratio reaches a value of 6.28 (enhancement behavior). Meanwhile, the enhancement becomes saturated when the volume of the noncylindrical shape continues to increase (saturation behavior). The analysis of average diffusivity of water molecules helps to reveal the mechanism underlying the two behaviors whereas Poiseuille's law fails to explain them. These results pave a way for designing high-flow nanochannels and provide insight into water permeation across biological water nanochannels.

  12. Transdermal delivery of betahistine hydrochloride using microemulsions: physical characterization, biophysical assessment, confocal imaging and permeation studies.

    PubMed

    Hathout, Rania M; Nasr, Maha

    2013-10-01

    Transdermal delivery of betahistine hydrochloride encapsulated in various ethyl oleate, Capryol 90(®), Transcutol(®) and water microemulsion formulations was studied. Two different kinds of phase diagrams were constructed for the investigated microemulsion system. Pseudoplastic flow that is preferable for skin delivery was recorded for the investigated microemulsions. A balanced and bicontinuous microemulsion formulation was suggested and showed the highest permeation flux (0.50±0.030mgcm(-2)h(-1)). The effect of the investigated microemulsions on the skin electrical resistance was used to explain the high permeation fluxes obtained. Confocal laser scanning microscopy was used to confirm the permeation enhancement and to reveal the penetration pathways. The results obtained suggest that the proposed microemulsion system highlighted in the current work can serve as a promising alternative delivery means for betahistine hydrochloride. PMID:23732802

  13. Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

    SciTech Connect

    Simpson, Lin Jay

    2015-07-28

    Thin film electronic devices (or stacks integrated with a substrate) that include a permeation barrier formed of a thin layer of metal that provides a light transmitting and electrically conductive layer, wherein the electrical conductive layer is formed on a surface of the substrate or device layer such as a transparent conducting material layer with pin holes or defects caused by manufacturing and the thin layer of metal is deposited on the conductive layer and formed from a self-healing metal that forms self-terminating oxides. A permeation plug or block is formed in or adjacent to the thin film of metal at or proximate to the pin holes to block further permeation of contaminants through the pin holes.

  14. Novel pore-lining residues in CFTR that govern permeation and open-channel block.

    PubMed

    McDonough, S; Davidson, N; Lester, H A; McCarty, N A

    1994-09-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) is both a member of the ATP-binding cassette superfamily and a Cl(-)-selective ion channel. We investigated the permeation pathway of human CFTR with measurements on conduction and open-channel blockade by diphenylamine-2-carboxylic acid (DPC). We used site-directed mutagenesis and oocyte expression to locate residues in transmembrane domain (TM) 6 and TM 12 that contact DPC and control rectification and single-channel conductances. Thus, TM 12 and the previously investigated TM 6 line the CFTR pore. In each TM, residues in contact with DPC are separated by two turns of an alpha helix. The contributions of TM 6 and TM 12 to DPC block and Cl- permeation, however, are not equivalent. The resulting structural model for the conduction pathway may guide future studies of permeation in other Cl- channels and ATP-binding cassette transporters. PMID:7522483

  15. Unimpeded Permeation of Water Through Helium-Leak-Tight Graphene-Based Membranes

    NASA Astrophysics Data System (ADS)

    Nair, R. R.; Wu, H. A.; Jayaram, P. N.; Grigorieva, I. V.; Geim, A. K.

    2012-01-01

    Permeation through nanometer pores is important in the design of materials for filtration and separation techniques and because of unusual fundamental behavior arising at the molecular scale. We found that submicrometer-thick membranes made from graphene oxide can be completely impermeable to liquids, vapors, and gases, including helium, but these membranes allow unimpeded permeation of water (H2O permeates through the membranes at least 1010 times faster than He). We attribute these seemingly incompatible observations to a low-friction flow of a monolayer of water through two-dimensional capillaries formed by closely spaced graphene sheets. Diffusion of other molecules is blocked by reversible narrowing of the capillaries in low humidity and/or by their clogging with water.

  16. Influence of temperature on oxygen permeation through ion transport membrane to feed a biomass gasifier

    NASA Astrophysics Data System (ADS)

    Antonini, T.; Foscolo, P. U.; Gallucci, K.; Stendardo, S.

    2015-11-01

    Oxygen-permeable perovskite membranes with mixed ionic-electronic conducting properties can play an important role in the high temperature separation of oxygen from air. A detailed design of a membrane test module is presented, useful to test mechanical resistance and structural stability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) capillary membrane in the reactor environment. Preliminary experimental results of membrane permeation tests highlight the positive effect of temperature on perovskite materials. This behaviour is also confirmed by a computational model of char combustion with oxygen permeated through the membrane module, when it is placed inside a gasifier reactor to provide the necessary input of heat to the gasification endothermic process. The results show that the temperature affects the oxygen permeation of the BSCF membrane remarkably.

  17. Method for the evaluation of the permeation characteristics of protective glove materials.

    PubMed

    Jencen, D A; Hardy, J K

    1988-06-01

    A method is described to evaluate the permeation characteristics of glove materials by chemical solvents. The collecting medium (helium) is continuously monitored by a flame ionization detector (FID) of a gas chromatograph (GC). Immediately following a steady-state condition, quantitative data are acquired on-line by a computer. A two-position GC sampling valve and computer-controlled data acquisition and analysis require minimal operator attention. For the 8 materials and 6 solvents investigated, thickness-normalized breakthrough times and steady-state permeation rates ranged from 9.10 min/mil to greater than 4 hr/mil and from 0.2048 to 9112 micrograms/min/cm2/mil, respectively. A modification of the procedure which allowed the determination of the effect of temperature on permeation for 4 glove/solvent pairs was evaluated also. PMID:3400594

  18. The influence of corneocyte structure on the interpretation of permeation profiles of nanoparticles across skin

    NASA Astrophysics Data System (ADS)

    Pinheiro, T.; Pallon, J.; Alves, L. C.; Veríssimo, A.; Filipe, P.; Silva, J. N.; Silva, R.

    2007-07-01

    The permeability of skin to nanoparticles of titanium dioxide (TiO 2) used in sunscreens as a reflector of the UV wavelengths of sunlight, was examined using nuclear microscopy techniques. Special attention was given to the permeation characteristics of these nanoparticles across the outer layers of skin, the stratum corneum, in healthy and psoriatic skin condition. Aspects that may influence the interpretation of results such as sample preparation difficulties and skin condition were focused. Sample preparation can damage the integrity of the corneocyte layers inducing unwanted artefacts that may bias the evaluation of results. Irradiation conditions may also introduce distortions in the labile structures of human skin. Skin condition, such as loss of corneocyte cohesion occurring in psoriasis also influence the permeation profile of the nanoparticles. Weighing and accounting for these features in the examination of skin by nuclear microscopy is crucial to accurately assess the TiO 2 nanoparticles permeation depth.

  19. Mechanisms of gas permeation through polymer membranes. Summary technical report, September 1989--August 1991

    SciTech Connect

    Stern, S.A.

    1991-12-31

    The objective of the present study is to investigate the mechanisms of gas transport in and through polymer membranes and the dependence of these mechanisms on pressure and temperature. This information is required for the development of new, energy-efficient membrane processes for the separation of industrial gas mixtures. Such processes are based on the selective permeation of the components of gas mixtures through nonporous polymer membranes. Recent work has been focused on the permeation of gases through membranes made from glassy polymers, i.e., at temperatures below the glass transition of the polymers (Tg). Glassy polymers are very useful membrane materials for gas separations because of their high selectivity toward different gases. Gases permeate through nonporous polymer membranes by a ``solution-diffusion`` process. Consequently, in order to understand the characteristics of this process it is necessary to investigate also the mechanisms of gas solution and diffusion in glassy polymers. 23 refs., 10 figs., 4 tabs.

  20. Enhanced Permeation of an Antiemetic Drug from Buccoadhesive Tablets by Using Bile Salts as Permeation Enhancers: Formulation Characterization, In Vitro, and Ex Vivo Studies

    PubMed Central

    Jain, C. P.; Joshi, Garima; Kataria, Udichi; Patel, Komal

    2016-01-01

    Buccal bioadhesive bilayer tablets of prochlorperazine maleate were designed and formulated by using buccoadhesive polymers such as hydroxypropylmethyl cellulose, Carbopol 934P, and sodium alginate. Physicochemical characteristics like the uniformity of weight, hardness, thickness, surface pH, drug content, swelling index, microenvironment pH, in vitro drug release, and in vivo buccoadhesion time of the prepared tablets were found to be dependent on the type and composition of the buccoadhesive materials used. The effect of bile salts on the permeation was studied through porcine buccal mucosa and it was found that out of three bile salts incorporated (sodium glycholate, sodium taurocholate, and sodium deoxycholate), sodium glycholate enhanced the permeation rate of prochlorperazine maleate by an enhancement factor of 1.37.

  1. Investigations on permeation of mitomycin C through double layers of natural rubber gloves.

    PubMed

    Korinth, Gintautas; Schmid, Klaus; Midasch, Oliver; Boettcher, Melanie I; Angerer, Jürgen; Drexler, Hans

    2007-10-01

    Treating peritoneal carcinomatosis by the aggressive cytoreductive surgery with the hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) surgeons expose their gloved hands for up to 90 min to a peritoneal dialysis solution (PDS) containing mitomycin C (MMC). We investigated the permeation of MMC through the material of three different natural rubber gloves under conditions similar to the in-use during HIPEC as well as under worst-case exposure scenario. Two different methods, a two-chamber diffusion cell and a single-chamber glass chamber method, were used to demonstrate the permeation capability. The permeation of MMC dissolved in 0.9% NaCl solution and PDS through double natural rubber glove material was tested over 2 h using four concentrations (c = 0.004, 0.008, 0.016 and 0.4 mg ml(-1)) and three receptor fluids (0.9% NaCl solution, PDS and a novel artificial sweat). In none of four glass chamber experiments and in only one of 40 diffusion cell experiments was permeation through glove material detected. The permeation occurred between 15 and 30 min under worst-case exposure scenario at a approximately 100-fold higher MMC concentration than under in-use conditions during HIPEC. The double-layer natural rubber gloves tested were effective to prevent a permeation of MMC in vitro under HIPEC-similar exposure. Our results support the glove wearing procedure in our university hospital. However, occupational exposure to antineoplastic drugs should be minimized, since there is insufficient knowledge regarding harmful effects from a long-term exposure to low doses. PMID:17921240

  2. Experimental investigation of defect-assisted and intrinsic water vapor permeation through ultrabarrier films.

    PubMed

    Kim, Hyungchul; Singh, Ankit Kumar; Wang, Cheng-Yin; Fuentes-Hernandez, Canek; Kippelen, Bernard; Graham, Samuel

    2016-03-01

    In the development of ultrabarrier films for packaging electronics, the effective water vapor transmission rate is a combination of permeation through pinhole defects and the intrinsic permeation through the actual barrier film. While it is possible to measure the effective permeation rate through barriers, it is important to develop a better understanding of the contribution from defects to the overall effective barrier performance. Here, we demonstrate a method to investigate independently defect-assisted permeation and intrinsic permeation rates by observing the degradation of a calcium layer encapsulated with a hybrid barrier film, that is, prepared using atomic layer deposition (ALD) and plasma enhanced deposition (PECVD). The results are rationalized using an analytical diffusion model to calculate the permeation rate as a function of spatial position within the barrier. It was observed that a barrier film consisting of a PECVD SiN(x) layer combined with an ALD Al2O3/HfO(x) nanolaminate resulted in a defect-assisted water vapor transmission rate (WVTR) of 4.84 × 10(-5) g/m(2) day and intrinsic WVTR of 1.41 × 10(-4) g/m(2) day at 50 °C/85% RH. Due to the low defect density of the tested barrier film, the defect-assisted WVTR was found to be three times lower than the intrinsic WVTR, and an effective (or total) WVTR value was 1.89 × 10(-4) g/m(2) day. Thus, improvements of the barrier performance should focus on reducing the number of defects while also improving the intrinsic barrier performance of the hybrid layer. PMID:27036786

  3. Ultrafast Viscous Permeation of Organic Solvents Through Diamond-Like Carbon Nanosheets

    NASA Astrophysics Data System (ADS)

    Karan, Santanu; Samitsu, Sadaki; Peng, Xinsheng; Kurashima, Keiji; Ichinose, Izumi

    2012-01-01

    Chemical, petrochemical, energy, and environment-related industries strongly require high-performance nanofiltration membranes applicable to organic solvents. To achieve high solvent permeability, filtration membranes must be as thin as possible, while retaining mechanical strength and solvent resistance. Here, we report on the preparation of ultrathin free-standing amorphous carbon membranes with Young’s moduli of 90 to 170 gigapascals. The membranes can separate organic dyes at a rate three orders of magnitude greater than that of commercially available membranes. Permeation experiments revealed that the hard carbon layer has hydrophobic pores of ~1 nanometer, which allow the ultrafast viscous permeation of organic solvents through the membrane.

  4. Tritium permeation and related studies on barrier treated 316 stainless steel

    SciTech Connect

    Gilbert, E.R.; Allen, R.P.; Baldwin, D.L.; Bell, R.D.; Brimhall, J.L.; Clemmer, R.G.; Marschman, S.C.; McKinnon, M.A.; Page, R.E.; Powers, H.G.; Chalk, S.G.

    1991-09-01

    To verify the performance of permeation-resistant cladding for tritium targets designed for a New Production Reactor Light Water Reactor, a tritium test facility was designed, developed, and certified. Testing is ongoing to verify the performance of reference designed targets. Accurate measurements were taken of tritium permeating from barrier-coated cladding specimens immersed in high-temperature autoclaves configured to simulate reactor coolant conditions. The tritium test pressure is controlled by heating a zirconium-alloy getter, previously charged with tritium, to a temperature that corresponds to a specified test pressure.

  5. Silicon Carbide as a tritium permeation barrier in tungsten plasma-facing components

    NASA Astrophysics Data System (ADS)

    Wright, G. M.; Durrett, M. G.; Hoover, K. W.; Kesler, L. A.; Whyte, D. G.

    2015-03-01

    The control of tritium inventory is of great importance in future fusion reactors, not only from a safety standpoint but also to maximize a reactor's efficiency. Due to the high mobility of hydrogenic species in tungsten (W) one concern is the loss of tritium from the system via permeation through the tungsten plasma-facing components (PFC). This can lead to loss of tritium through the cooling channels of the wall thereby mandating tritium monitoring and recovery methods for the cooling system of the first wall. The permeated tritium is then out of the fuel cycle and cannot contribute to energy production until it is recovered and recycled into the system.

  6. Application of pervaporation and vapor permeation processes to separate aqueous ethanol solution through chemically modified Nylon 4 membranes

    SciTech Connect

    Wang, Y.H.; Teng, M.Y.; Lee, K.R.; Wang, D.M.; Lai, J.Y.

    1998-08-01

    The pervaporation performance of a Nylon 4 membrane, chemically grafted by N,N-dimethylaminoethyl methacrylate (DMAEM), DMAEM-g-N4, was studied by measurement of the permeation ratio and the pervaporation separation index. It was found that the water permselectivity and permeation rate for the chemically modified Nylon 4 membrane were higher than those of the unmodified Nylon 4 membrane. Optimum pervaporation results, a separation factor of 28.3, and a permeation rate of 439 g/m{sup 2}{center_dot}h, were obtained when the degree of grafting was 12.7%. It was also found that all the permeation ratios at low temperature were less than unity. In addition, compared with pervaporation, vapor permeation effectively increases the permselectivity of water.

  7. Water Vapor Permeation of Metal Oxide/Polymer Coated Plastic Films

    NASA Astrophysics Data System (ADS)

    Numata, Yukihiro; Oya, Toshiyuki; Kuwahara, Mitsuru; Ito, Katsuya

    Barrier performance to water vapor permeation of ceramic coated layers deposited on flexible polymer films is of great interest to food packaging, medical device packaging and flat panel display industries. In this study, a new type film in which a ceramic layer is deposited on a polymer coated film was proposed for lower water vapor permeation. It is important how to control interfacial properties between each layer and film for good barrier performance. Several kinds of polymer coated materials were prepared for changing surface free energy of the films before and after depositing the ceramic layer. The ceramic layer, which is composed of mixed material of SiO2 and Al2O3, was adopted under the same conditions. The following results were obtained; 1) Water vapor permeation is not related to the surface energy of polymer coated films, 2) After depositing the ceramic layer, however, a strong correlation is observed between the water vapor permeation and surface free energy. 3) The phenomenon is considered that the polarity of the polymer layers plays a key role in changing the structure of ceramic coated layers.

  8. Fully automatic flow-based device for monitoring of drug permeation across a cell monolayer.

    PubMed

    Zelená, Lucie; Marques, Sara S; Segundo, Marcela A; Miró, Manuel; Pávek, Petr; Sklenářová, Hana; Solich, Petr

    2016-01-01

    A novel flow-programming setup based on the sequential injection principle is herein proposed for on-line monitoring of temporal events in cell permeation studies. The permeation unit consists of a Franz cell with its basolateral compartment mixed under mechanical agitation and thermostated at 37 °C. The apical compartment is replaced by commercially available Transwell inserts with a precultivated cell monolayer. The transport of drug substances across epithelial cells genetically modified with the P-glycoprotein membrane transporter (MDCKII-MDR1) is monitored on-line using rhodamine 123 as a fluorescent marker. The permeation kinetics of the marker is obtained in a fully automated mode by sampling minute volumes of solution from the basolateral compartment in short intervals (10 min) up to 4 h. The effect of a P-glycoprotein transporter inhibitor, verapamil as a model drug, on the efficiency of the marker transport across the cell monolayer is thoroughly investigated. The analytical features of the proposed flow method for cell permeation studies in real time are critically compared against conventional batch-wise procedures and microfluidic devices. PMID:26615589

  9. Iontophoretic Permeation of Lisinopril at Different Current Densities and Drug Concentrations

    PubMed Central

    Jain, Ashish; Nayak, Satish; Soni, Vandana

    2012-01-01

    Purpose: The purpose of the present work was to assess iontophoretic permeation of Lisinopril at different current densities and concentrations for development of patient-controlled active transdermal system. Methods: In vitro iontophoretic transdermal delivery of Lisinopril across the pigskin was investigated at three different drug concentrations and three different current densities (0.25- 0.75 mA/cm2) in the donor cell of the diffusion apparatus, using cathodal iontophoresis along with the passive controls. Results: For passive permeation, the steady state flux significantly increased with the increasing of donor drug concentration. At all concentration levels, iontophoresis considerably increased the permeation rate compared to passive controls. Iontophoretic transport of Lisinopril was to be found increase with current densities. Flux enhancement was highest at the lowest drug load and lowest at the highest drug load. Conclusion: The obtained results indicate that permeation rate of Lisinopril across the pigskin can be considerably enhanced, controlled or optimized by the use of Iontophoresis technique. PMID:24312799

  10. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... requirements specified in 40 CFR 1051.110 or in this section. (4) Small SI fuel tanks must meet the permeation... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD... tanks to a family emission limit for calculating evaporative emission credits as described in subpart...

  11. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... requirements specified in 40 CFR 1051.110 or in this section. (4) Small SI fuel tanks must meet the permeation... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD... tanks to a family emission limit for calculating evaporative emission credits as described in subpart...

  12. 40 CFR 1060.521 - How do I test fuel caps for permeation emissions?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false How do I test fuel caps for permeation emissions? 1060.521 Section 1060.521 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND...

  13. 40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... requirements specified in 40 CFR 1051.110 or in this section. (4) Small SI fuel tanks must meet the permeation... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD... tanks to a family emission limit for calculating evaporative emission credits as described in subpart...

  14. Peculiarities in gel permeation chromatography of flexible-chain polymers on macroporous swelling sorbents.

    PubMed

    Belenkii, B G; Vilenchik, L Z; Nesterov, V V; Kolegov, V J; Frenkel, S Y

    1975-06-18

    In gel permeation chromatography on macroporous swelling sorbents, deviations from the Benoit principle of universal calibration were observed. It is suggested that these are caused by different degrees of thermodynamic compatibility of the eluted polymers with the sorbent matrix. PMID:1150817

  15. Hydrogen permeation and diffusion in a 0. 2C-13Cr martensitic stainless steel

    SciTech Connect

    Xu, J.; Sun, X.K. . State Key Lab. of RSA); Yuan, X.Z.; Wei, B.M. . Dept. of Applied Chemistry)

    1993-10-01

    The phenomenon of hydrogen embrittlement for engineering alloys, especially for alloy steels, has long attracted the attention of material researchers. Presently, it is thought that the occurrence of the phenomenon correlates with the processes of hydrogen entry and transport in metals. Therefore, a great effort has been made to understand the hydrogen permeation and diffusion in metals and alloys. Even so, the knowledge of the hydrogen permeation and diffusion in steels with a martensitic structure is still limited. In most of the investigations performed on martensite, the electrochemical permeation technique was employed for measurement; hence, only limited data near ambient temperature have been determined. A few results obtained at higher temperature are very scattered also. For instance, the hydrogen diffusivity of AISI 4130 steel in the quenched and tempered (martensite) condition is 2 orders of magnitude higher than of cryoformed 301 stainless steel (containing 90% of [alpha][prime] martensite). In the present work, the hydrogen permeability and diffusivity of a 0.2C-13Cr martensitic stainless steel (2Cr13), roughly corresponding to AISI 420, was determined by means of the gaseous permeation technique. Measurements were made above ambient temperature.

  16. Internally staged permeator prepared from annular hollow fibers for gas separation

    SciTech Connect

    Li, K.; Wang, D.; Li, D.; Teo, W.K.

    1998-04-01

    A polysulfone/polyethersulfone annular hollow-fiber (tube) membrane was prepared using a phase-inversion process, which is useful for further preparation of an internally staged permeator (ISP) for gas separation. This study focused on the techniques of fabricating the polysulfone/polyethersulfone annular-hollow-fiber membranes and its membrane permeators for gas enrichment. Two homogeneous polymer solutions comprising polysulfone/DMAc and polyethersulfone/NMP/water, respectively, were prepared and extruded with a triple-orifice spinneret into an annular-hollow-fiber membrane that possesses two distinct skin layers and is capable of providing two separation stages internally for gas separation. The performance of the ISP fabricated from the prepared annular hollow-fiber membrane was evaluated theoretically and experimentally under co/countercurrent and countercurrent flow patterns for various binary gas mixtures. The mathematical models generally describe satisfactorily the observed experimental results. A parametric study reveals that while, in general, better separation is available at lower values of overall stage cuts, highly purified permeate products could be achieved at higher values of overall stage cuts if the concentration of a permeating component in the feed stock is relatively high.

  17. Whey as a brewing material. III. Fermentation of wort containing hydrolyzed whey permeate

    SciTech Connect

    Tenney, R.I.

    1981-01-01

    Ultrafiltration of whey removes most of the protein, leaving lactose and minerals in the permeate. Salinity may be controlled by demineralization, resulting in a product that ferments easily, yielding beers of normal and controllable composition and character. Up to 30% extracts may be derived from whey. Several strains of yeast isolated from breweries are capable of the fermentation.

  18. Molecular Dynamics Investigation of Ion Sorption and Permeation in Desalination Membranes.

    PubMed

    Kolev, Vesselin; Freger, Viatcheslav

    2015-11-01

    With the purpose of gaining insights into the mechanisms of ion uptake and permeation in desalination membranes, MD investigation of a model polyamide membrane was carried out. A relatively large membrane (45K atoms) was assembled, which closely matched real desalination membrane in terms of chemistry and water permeability. Simulations demonstrate that the mechanism of ion uptake distinctly differs from mean-field approaches assuming a smeared excluding Donnan potential. Ion sorption on charged sites in the membrane phase appears to be highly localized, due to electrostatic forces dominating over translational entropy. Moreover, sorption on partial atomic charges becomes possible as well, which greatly enhances salt (co-ion) uptake and weakens the effect of fixed charges on salt exclusion. This could explain high ion uptake measured in polyamide membranes for both co- and counterions and variations of ion sorption and permeation at low salt concentrations. On the other hand, present simulations greatly overestimate ion permeability, which could be explained by a more open structure than in real membranes, in which dense polyamide fragments may efficiently block ion permeation. Unfortunately, MD cannot analyze ion uptake and permeation in dense fragments containing too few ions, which calls for new approaches to studying barrier properties of polyamide. PMID:26451495

  19. Quantitative aspects of drug permeation across in vitro and in vivo barriers.

    PubMed

    Krämer, Stefanie D

    2016-05-25

    The kinetics of permeation across epithelial and endothelial cell sheets and across cell membranes is determinant for the pharmacokinetics of a drug. In vitro transport experiments with cultured cells or artificial barriers have tremendously improved the predictability of the in vivo behaviour of tested compounds. This article focuses on the parameters and calculation methods that are used to describe permeation quantitatively, with a focus on in vitro experiments and the prediction of intestinal absorption and blood-brain barrier passage. It shows under which in vitro experimental conditions standard calculations are adequate and under which conditions equations should be adapted to the experimental details. The impact of volume differences between donor and receiver compartments, pH gradients, addition of albumin, accumulation in the barrier and unidirectional transport by an efflux transporter on the results is shown in simulations. The article should make researchers aware of experimental factors that affect the outcome of a permeation experiment and how to account for this during data analysis. Finally, strategies to predict the in vivo behaviour of a compound based on the in vitro data are discussed. The goal of the article is to support researchers in choosing experimental conditions and calculation methods that deliver appropriate and reproducible results in permeation studies in vitro. PMID:26493585

  20. Molecular Mechanisms of How Mercury Inhibits Water Permeation through Aquaporin-1: Understanding by Molecular Dynamics Simulation

    PubMed Central

    Hirano, Yoshinori; Okimoto, Noriaki; Kadohira, Ikuko; Suematsu, Makoto; Yasuoka, Kenji; Yasui, Masato

    2010-01-01

    Abstract Aquaporin (AQP) functions as a water-conducting pore. Mercury inhibits the water permeation through AQP. Although site-directed mutagenesis has shown that mercury binds to Cys189 during the inhibition process, it is not fully understood how this inhibits the water permeation through AQP1. We carried out 40 ns molecular dynamics simulations of bovine AQP1 tetramer with mercury (Hg-AQP1) or without mercury (Free AQP1). In Hg-AQP1, Cys191 (Cys189 in human AQP1) is converted to Cys-SHg+ in each monomer. During each last 10 ns, we observed water permeation events occurred 23 times in Free AQP1 and never in Hg-AQP1. Mercury binding did not influence the whole structure, but did induce a collapse in the orientation of several residues at the ar/R region. In Free AQP1, backbone oxygen atoms of Gly190, Cys191, and Gly192 lined, and were oriented to, the surface of the water pore channel. In Hg-AQP1, however, the SHg+ of Cys191-SHg+ was oriented toward the outside of the water pore. As a result, the backbone oxygen atoms of Gly190, Cys191, and Gly192 became disorganized and the ar/R region collapsed, thereby obstructing the permeation of water. We suggest that mercury disrupts the water pore of AQP1 through local conformational changes in the ar/R region. PMID:20409470

  1. Repeatability and Reproducibility Standard Deviations in the Measurement of Trace Moisture Generated Using Permeation Tubes

    PubMed Central

    Huang, Peter H.; Kacker, Raghu

    2003-01-01

    Permeation-tube moisture generators are used in industry as calibrated sources of water vapor and carrier gas mixtures. Measurements were made using three permeation-tube moisture generators of the type used in the semiconductor industry. This paper describes repeatability and reproducibility standard deviations in measurement of moisture concentration from such generators. Repeatability refers to measurements within a system and reproducibility refers to measurements between systems. Two independent methods were used to measure the realized concentration of water vapor. The first measurement, the calculated value, was determined using calibrated permeation rate of permeation-tube and flow rate of dry carrier gas. This is the industrial method of evaluating moisture concentration. The second measurement, the measured value, was determined using the low frost-point generator at the National Institute of Standards and Technology (NIST) and a quartz-crystal-micro-balance. Four pairs of independent measurements for each generator and for six nominal levels in the range from10 nL/L to 100 nL/L were made. The characteristic used to quantify repeatability and reproducibility standard deviations in industrial measurements is the calculated value minus the measured value. Repeatability standard deviation ranges from 1 nL/L to 2 nL/L, approximately. Reproducibility standard deviation ranges from 2 nL/L to 8 nL/L, approximately. The documentary ASTM standard E691-99 was used for both data validation and quantification of the repeatability and reproducibility standard deviations. PMID:27413608

  2. In Vitro Permeation of Metals through Human Skin: A Review and Recommendations.

    PubMed

    Franken, Anja; Eloff, Frederik C; Du Plessis, Jeanetta; Du Plessis, Johannes L

    2015-12-21

    During the last few decades, the interest in skin permeation of, specifically, metals has increased with the in vitro method utilizing diffusion cells as the prominent method of investigating permeability. This review provides a systematic synopsis focused on an in vitro diffusion cell method utilizing human skin and examines the differences in experimental design as this could influence the results obtained. The permeation of metals such as chromium, cobalt, copper, gold, lead, mercury, nickel, palladium, platinum, rhodium, silver, titanium, and zinc are discussed. The metals included in this review, except for titanium and zinc, can permeate through intact human skin under physiological conditions. On the basis of flux values, the order of permeability could be summarized as Cu > Pb > Cr > Ni > Co > Pt > Hg > Rh (excluding nanoparticles). Permeability of metals through human skin is highly variable with the different methodologies as a contributing factor. Furthermore, metals are retained in the skin which could lead to reservoir (depot) formation and extended exposure even after the removal thereof from the outer surface of the skin. Finally, recommendations are provided on the standardization of experimental design and format of data reporting to enable the comparison of results from future in vitro metal permeation studies. PMID:26555458

  3. Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

    DOE PAGESBeta

    Pawelko, R. J.; Shimada, M.; Katayama, K.; Fukada, S.; Humrickhouse, P. W.; Terai, T.

    2015-11-28

    This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determinemore » operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.« less

  4. Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

    SciTech Connect

    Pawelko, R. J.; Shimada, M.; Katayama, K.; Fukada, S.; Humrickhouse, P. W.; Terai, T.

    2015-11-28

    This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determine operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.

  5. Evaluation of Skin Permeation and Analgesic Activity Effects of Carbopol Lornoxicam Topical Gels Containing Penetration Enhancer

    PubMed Central

    Al-Suwayeh, Saleh A.; Taha, Ehab I.; Al-Qahtani, Fahad M.; Ahmed, Mahrous O.; Badran, Mohamed M.

    2014-01-01

    The current study was designed to develop a topical gel formulation for improved skin penetration of lornoxicam (LOR) for enhancement of its analgesic activity. Moreover, the effect of different penetration enhancers on LOR was studied. The LOR gel formulations were prepared by using hydroxylpropyl methylcellulose (HPMC) and carbopol. The carbopol gels in presence of propylene glycol (PG) and ethanol were developed. The formulated gels were characterized for pH, viscosity, and LOR release using Franz diffusion cells. Also, in vitro skin permeation of LOR was conducted. The effect of hydroxypropyl β-cyclodextrin (HP β-CD), beta-cyclodextrin (β-CD), Tween 80, and oleic acid on LOR permeation was evaluated. The optimized LOR gel formulation (LORF8) showed the highest flux (14.31 μg/cm2/h) with ER of 18.34 when compared to LORF3. Incorporation of PG and HP β-CD in gel formulation (LORF8) enhanced the permeation of LOR significantly. It was observed that LORF3 and LORF8 show similar analgesic activity compared to marketed LOR injection (Xefo). This work shows that LOR can be formulated into carbopol gel in presence of PG and HP β-CD and may be promising in enhancing permeation. PMID:25045724

  6. Corrosion and hydrogen permeation of A216 Grade WCA steel in hydrothermal magnesium-containing brines

    SciTech Connect

    Haberman, J.H.; Frydrych, D.J.; Westerman, R.E.

    1988-03-01

    Corrosion rates determined at 1 month in 150/degree/C brine increased with magnesium concentration. The structure of the corrosion product, as determined by x-ray diffraction, depended upon the magnesium concentration. In brines with less than 10,000 ppM magnesium, the primary corrosion product had a spinel structure characteristic of magnetite or magnesioferrite. In brines containing magnesium concentrations greater than 20,000 ppM, the primary corrosion product had the amakinite structure characteristic of a complex iron-magnesium hydroxide. The high corrosion rates observed in brines containing high magnesium concentrations suggest that the corrosion products having the amakinite structure is less protective than corrosion products having the spinel structure. Corrosion rates in high-magnesium (inclusion) brine determined over a 6-month test duration were essentially constant. Hydrogen permeation rates observed in exposing mild steel to high-Mg/sup 2/plus// brine at 150/degree/C could be potentially damaging to a mild steel waste package container. The rate of hydrogen permeation was proportional to the brine flow rate in the autoclave. Thiourea additions to the brine increased the hydrogen permeation rate; sulfate and bromide ion additions did not. The maximum gaseous hydrogen pressure attainable is not known (based on 3Fe /plus/ 4H/sub 2/O /plus/ Fe(sub 3)O /plus/ 4H/sub 2/, would be /approximately/900 atmospheres), and the dependence of permeation rate on temperature is not known. 8 refs., 13 figs., 3 tabs.

  7. Effects of Solvent Deposited Enhancers on Transdermal Permeation and their Relationship with Emax

    PubMed Central

    Ibrahim, Sarah A.; Li, S. Kevin

    2009-01-01

    Many topical pharmaceuticals such as aerosols, topical sprays, and hydro-alcoholic and polymer based gels contain chemical enhancers. The objectives of the present study were to (a) determine the enhancement effects induced by enhancers deposited from a volatile solvent on human epidermal membrane (HEM) upon transdermal permeation enhancement, (b) compare these enhancement factors with Emax, and (c) examine the relationship between enhancer-induced permeation enhancement and stratum corneum equilibrium uptake enhancement. In this study, HEM was treated with enhancer/ethanol (enhancer dissolved in ethanol). After the evaporation of ethanol, passive transport experiments were conducted using corticosterone (CS) as the model permeant. The uptake of another model corticosteroid, estradiol (E2β), into the intercellular lipid domain of stratum corneum after enhancer/ethanol treatment was also determined. The results show a correlation between Emax and the enhancement effect of most enhancers when the enhancers were deposited on the skin using the volatile solvent ethanol. The data suggest that the CS transport rate limiting domain was likely the same as the intercellular lipid domain probed by E2β uptake. The correlation between steady-state permeation enhancement and uptake enhancement into the intercellular lipid domain suggests that the permeation enhancement mechanism is primarily due to enhancement of permeant partitioning into the transport rate limiting domain. PMID:19331847

  8. Effects of the polarizability and packing density of transparent oxide films on water vapor permeation.

    PubMed

    Koo, Won Hoe; Jeong, Soon Moon; Choi, Sang Hun; Kim, Woo Jin; Baik, Hong Koo; Lee, Sung Man; Lee, Se Jong

    2005-06-01

    The tin oxide and silicon oxide films have been deposited on polycarbonate substrates as gas barrier films, using a thermal evaporation and ion beam assisted deposition process. The oxide films deposited by ion beam assisted deposition show a much lower water vapor transmission rate than those by thermal evaporation. The tin oxide films show a similar water vapor transmission rate to the silicon oxide films in thermal evaporation but a lower water vapor transmission rate in IBAD. These results are related to the fact that the permeation of water vapor with a large dipole moment is affected by the chemistry of oxides and the packing density of the oxide films. The permeation mechanism of water vapor through the oxide films is discussed in terms of the chemical interaction with water vapor and the microstructure of the oxide films. The chemical interaction of water vapor with oxide films has been investigated by the refractive index from ellipsometry and the OH group peak from X-ray photoelectron spectroscopy, and the microstructure of the composite oxide films was characterized using atomic force microscopy and a transmission electron microscope. The activation energy for water vapor permeation through the oxide films has also been measured in relation to the permeation mechanism of water vapor. The diffusivity of water vapor for the tin oxide films has been calculated from the time lag plot, and its implications are discussed. PMID:16852387

  9. Development of luminescence procedures to evaluate permeation of multi-ring polyaromatic compounds through protective materials

    SciTech Connect

    Vo-Dinh, T.; White, D.A.

    1987-04-01

    This study describes two practical and simple luminescence techniques developed to evaluate the efficacy of protective clothing materials against permeation of multi-ring polyaromatic compounds contained in heavy oil and petroleum products. The procedures use a rapid and simple technique based on room temperature phosphorimetry and fluorescence detection in which a portable fiberoptics luminoscope was used.

  10. Design criteria for extraction with chemical reaction and liquid membrane permeation

    NASA Technical Reports Server (NTRS)

    Bart, H. J.; Bauer, A.; Lorbach, D.; Marr, R.

    1988-01-01

    The design criteria for heterogeneous chemical reactions in liquid/liquid systems formally correspond to those of classical physical extraction. More complex models are presented which describe the material exchange at the individual droplets in an extraction with chemical reaction and in liquid membrane permeation.

  11. Efficient ethanol recovery from fermentation broths with integrated distillation-vapor permeation hybrid process

    EPA Science Inventory

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative hybrid process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane s...

  12. Molecular mechanisms of how mercury inhibits water permeation through aquaporin-1: understanding by molecular dynamics simulation.

    PubMed

    Hirano, Yoshinori; Okimoto, Noriaki; Kadohira, Ikuko; Suematsu, Makoto; Yasuoka, Kenji; Yasui, Masato

    2010-04-21

    Aquaporin (AQP) functions as a water-conducting pore. Mercury inhibits the water permeation through AQP. Although site-directed mutagenesis has shown that mercury binds to Cys189 during the inhibition process, it is not fully understood how this inhibits the water permeation through AQP1. We carried out 40 ns molecular dynamics simulations of bovine AQP1 tetramer with mercury (Hg-AQP1) or without mercury (Free AQP1). In Hg-AQP1, Cys191 (Cys189 in human AQP1) is converted to Cys-SHg+ in each monomer. During each last 10 ns, we observed water permeation events occurred 23 times in Free AQP1 and never in Hg-AQP1. Mercury binding did not influence the whole structure, but did induce a collapse in the orientation of several residues at the ar/R region. In Free AQP1, backbone oxygen atoms of Gly190, Cys191, and Gly192 lined, and were oriented to, the surface of the water pore channel. In Hg-AQP1, however, the SHg+ of Cys191-SHg+ was oriented toward the outside of the water pore. As a result, the backbone oxygen atoms of Gly190, Cys191, and Gly192 became disorganized and the ar/R region collapsed, thereby obstructing the permeation of water. We suggest that mercury disrupts the water pore of AQP1 through local conformational changes in the ar/R region. PMID:20409470

  13. 40 CFR 90.127 - Fuel line permeation from nonhandheld engines and equipment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... permeation emission standard of 15 g/m2/day when measured according to the test procedure described in 40 CFR... standards that apply for these engines and equipment in California for the same model year (see 40 CFR 1060... specifications in SAE J30 as described in 40 CFR 1060.810. (ii) R12 specifications in SAE J30 as described in...

  14. Reduction of tritium permeation through Inconel 718 and Incoloy 800 HT by means of natural oxides

    NASA Astrophysics Data System (ADS)

    Aiello, A.; Utili, M.; Ciampichetti, A.

    2011-10-01

    Chronical releases of tritium from the helium primary coolant into the water secondary coolant is a fundamental safety issue in the design of a fusion reactor steam generator. It is well known that the steam/water circuit of a fusion reactor would be considered not relevant from a radiological point of view, while if a strong permeation of tritium will be present it will be released together with incondensable gases in the condenser. The permeation of hydrogen isotopes through candidate steam generator materials in different conditions was studied in the past. Further experiments demonstrated that nickel alloys of nuclear interest are always covered by a thin and adherent oxide layer able to reduce permeation of orders of magnitude. The major objective of this work is the evaluation of the permeated flux through nickel alloys, when exposed to pure hydrogen and to an oxidant gas stream, to verify the real permeability of these materials in conditions close to those foreseen in the helium side of the steam generator.

  15. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... equipment with structurally integrated nylon fuel tanks (as defined in 40 CFR 1054.801). (b) Certification... meet the fuel tank permeation standards in 40 CFR 1060.103. (iii) Engines and equipment must use only... 40 CFR part 1054, subpart H. (3) The emission standards in this section apply over a useful life...

  16. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... equipment with structurally integrated nylon fuel tanks (as defined in 40 CFR 1054.801). (b) Certification... meet the fuel tank permeation standards in 40 CFR 1060.103. (iii) Engines and equipment must use only... 40 CFR part 1054, subpart H. (3) The emission standards in this section apply over a useful life...

  17. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... equipment with structurally integrated nylon fuel tanks (as defined in 40 CFR 1054.801). (b) Certification... meet the fuel tank permeation standards in 40 CFR 1060.103. (iii) Engines and equipment must use only... 40 CFR part 1054, subpart H. (3) The emission standards in this section apply over a useful life...

  18. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... equipment with structurally integrated nylon fuel tanks (as defined in 40 CFR 1054.801). (b) Certification... meet the fuel tank permeation standards in 40 CFR 1060.103. (iii) Engines and equipment must use only... 40 CFR part 1054, subpart H. (3) The emission standards in this section apply over a useful life...

  19. 40 CFR 90.129 - Fuel tank permeation from handheld engines and equipment.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... equipment with structurally integrated nylon fuel tanks (as defined in 40 CFR 1054.801). (b) Certification... meet the fuel tank permeation standards in 40 CFR 1060.103. (iii) Engines and equipment must use only... 40 CFR part 1054, subpart H. (3) The emission standards in this section apply over a useful life...

  20. Permeation of protective garment material by liquid benzene and by tritiated water

    SciTech Connect

    Weeks, R.W. Jr.; McLeod, M.J.

    1982-03-01

    Although the toxic and carcinogenic natures of benzene have been known for some time, the 10 ppm regulation governing human exposure to it as a vapor or a liquid dates only from the 1970's. The present work presents the rate at which liquid benzene breaks through certain protective garment materials and, thus, provides information concerning the protection these materials provide. Presented here are the results of such measurements on butyl, natural rubber latex, neoprene latex, nitrile latex, surgical rubber latex, Teflon, Tyvek 1422A, poly(vinyl chloride), and Viton elastomers, and the following composites or supported elastomers:butyl-coated nylon; ethylene vinyl acetate/polyethylene-coated Tyvek 1422A;Poly(vinyl alcohol) and Saranex 15. Included in these determinations were studies to correlate the protective materials' swelling and weight changes following immersion in benzene with their breakthrough time, i.e., that time at which benzene was first detected in the aqueous phase of the permeation cell. This was done in hopes that ultimately a ''screening test'' might be recommended concerning the permeation of lack of permeation through given materials. Also included in this report are observations of the time required for tritium from tritiated water to permeate butyl rubber, nitrile latex, surgical rubber latex, and poly(vinyl alcohol).

  1. Development of novel polymer-stabilized diosmin nanosuspensions: in vitro appraisal and ex vivo permeation.

    PubMed

    Freag, May S; Elnaggar, Yosra S R; Abdallah, Ossama Y

    2013-09-15

    Scanty solubility and permeability of diosmin (DSN) are perpetrators for its poor oral absorption and high inter-subject variation. This article investigated the potential of novel DSN nanosuspensions to improve drug delivery characteristics. Bottom-up nanoprecipitation technique has been employed for nanosuspension development. Variables optimized encompassed polymeric stabilizer type, DSN: stabilizer ratio, excess stabilizer removal, spray drying, and mannitol incorporation. In vitro characterization included particle size (PS), infrared spectroscopy (IR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), and dissolution profile. Ex vivo permeation was assessed in rats using non-everted sac technique and HPLC. Optimal DSN nanosuspension (DSN:hydroxypropylmethyl cellulose HPMC 2:1) was prepared with acid base neutralization technique. The formula exhibited the lowest PS (336 nm) with 99.9% drug loading and enhanced reconstitution properties after mannitol incorporation. SEM and TEM revealed discrete, oval drug nanocrystals with higher surface coverage with HPMC compared to MC. DSN nanosuspension demonstrated a significant enhancement in DSN dissolution (100% dissolved) compared to crude drug (51%). Permeation studies revealed 89% DSN permeated from the nanosuspension after 120 min compared to non-detected amounts from drug suspension. Conclusively, novel DSN nanosuspension could successful improve its dissolution and permeation characteristics with promising consequences of better drug delivery. PMID:23830765

  2. Influence of collection solvent on permeation of di-n-octyl disulfide through nitrile glove material.

    PubMed

    Xu, Wenhai; Que Hee, Shane S

    2008-03-01

    The influence of collection solvents hexane and perfluorohexane on the permeation of the non-polar and non-volatile di-n-octyl disulfide (DOD) through nitrile glove material was investigated using the American Society for Testing and Materials (ASTM) F739-99a method. The weight and the thickness of the nitrile material increased about 6%, statistically significant at ppermeation for both collection solvents. Infrared reflectance examination revealed no spectral changes to glove surfaces. Gas chromatography/mass spectrometry analysis determined that the apparent DOD steady state permeation rate was 903+/-285 microg/(cm2 h) for hexane collection, and 6.92+/-2.27 microg/(cm2 h) for perfluorohexane collection. The ASTM normalized breakthrough time for DOD was 7-30 min for hexane collection, and 30-75 min for perfluorohexane collection. Perfluorohexane is a promising collection solvent for non-polar and non-volatile compounds permeating nitrile material. PMID:17662521

  3. Release and Skin Permeation of Scopolamine From Thin Polymer Films in Relation to Thermodynamic Activity.

    PubMed

    Kunst, Anders; Lee, Geoffrey

    2016-04-01

    The object was to demonstrate if the diffusional flux of the drug out of a drug-in-adhesive-type matrix and its subsequent permeation through an excised skin membrane is a linear function of the drug's thermodynamic activity in the thin polymer film. The thermodynamic activity, ap(*), is defined here as the degree of saturation of the drug in the polymer. Both release and release/permeation of scopolamine base from 3 different poylacrylate pressure-sensitive adhesives (PSAs) were measured. The values for ap(*) were calculated using previous published saturation solubilities, wp(s), of the drug in the PSAs. Different rates of release and release/permeation were determined between the 3 PSAs. These differences could be accounted for quantitatively by correlating with ap(*) rather than the concentration of the drug in the polymer films. At similar values for ap(*) the same release or release/permeation rates from the different polymers were measured. The differences could not be related to cross-linking or presence of ionizable groups of the polymers that should influence diffusivity. PMID:27019963

  4. Meloxicam transdermal delivery: effect of eutectic point on the rate and extent of skin permeation

    PubMed Central

    Mohammadi-Samani, Soliman; Yousefi, Gholamhossein; Mohammadi, Farhad; Ahmadi, Fatemeh

    2014-01-01

    Objective(s): Drug delivery through the skin can transfer therapeutic levels of drugs for pharmacological effects. Analgesics such as NSAIDs have gastrointestinal side effects and topical dosage forms of these drugs are mainly preferred, especially for local pains. Meloxicam is one of NSAIDs with no topical form in the market. In this research, we attempted to quantify the skin permeation of a meloxicam topical preparation and to show how permeation would be increased by using thymol as an enhancer. The effect of eutectic point of drug and thymol mixture on rate and extent of skin permeation was also studied. Materials and Methods: Different mixtures of thymol and meloxicam (2:8, 4:6, 5:5, 6:4, 8:2) were prepared and their melting point were obtained by differential scanning calorimetry. Then drug permeation was measured using diffusion cells and the Guinea pig skin. Results: Mixtures in ratios 5:5 and 4:6 of meloxicam / thymol showed a new endotherm at 149 and 140°C in DSC thermograms. The permeability of meloxicam from the creams containing 6:4, 5:5 and 4:6 ratios of meloxicam to thymol were 4.71, 15.2, 22.06 µg/cm2 respectively. This was significantly different from the cream of pure meloxicam (3.76 µg/cm2). Conclusion: This study set out to determine that thymol plays as a skin permeation enhancer and increases the meloxicam skin absorption and this enhancement is significant at the eutectic point of drug-enhancer mixture. PMID:24711894

  5. Simulated Permeation and Characterization of PEGylated Gold Nanoparticles in a Lipid Bilayer System.

    PubMed

    Oroskar, Priyanka A; Jameson, Cynthia J; Murad, Sohail

    2016-08-01

    PEGylated gold nanoparticles are considered suitable nanocarriers for use in biomedical applications and targeted drug delivery systems. In our previous investigation with the alkanethiol-functionalized gold nanoparticle, we found that permeation across a protein-free phospholipid membrane resulted in damaging effects of lipid displacement and water and ion leakage. In the present study, we carry out a series of coarse-grained molecular simulations to explore permeation of lipid bilayer systems by a PEGylated gold nanoparticle, especially at the bulk-liquid-lipid interface as well as the interface between the two lipid leaflets. Initially, we examine molecular-level details of a PEGylated gold nanoparticle (constructed from cycled annealing) in water and find a distribution of ligand configurations (from mushroom to brush states) present in nanoparticles with medium to high surface coverage. We also find that the characteristic properties of the PEGylated gold nanoparticle do not change when it is placed in a salt solution. In our permeation studies, we investigate events of water and ion penetration as well as lipid translocation while varying the ligand length, nanoparticle surface coverage, and ion concentration gradient of our system. Results from our studies show the following: (1) The number of water molecules in the interior of the membrane during ligand-coated nanoparticle permeation increases with PEGn-SH surface coverage, ligand length, and permeation velocity but is not sensitive to the ion concentration gradient. (2) Lipid molecules do not leave the membrane; instead they complete trans-bilayer lipid flip-flop with longer ligands and higher surface coverages. (3) The lack of formation of stable water pores prevents ion translocation. (4) The PEGylated nanoparticle causes less damage to the membrane overall due to favorable interactions with the lipid headgroups which may explain why experimentalists observe endocytosis of PEGylated nanocarriers in vivo

  6. Temperature dependence of proton permeation through a voltage-gated proton channel

    PubMed Central

    Kuno, Miyuki; Ando, Hiroyuki; Morihata, Hirokazu; Sakai, Hiromu; Mori, Hiroyuki; Sawada, Makoto

    2009-01-01

    Voltage-gated proton channels are found in many different types of cells, where they facilitate proton movement through the membrane. The mechanism of proton permeation through the channel is an issue of long-term interest, but it remains an open question. To address this issue, we examined the temperature dependence of proton permeation. Under whole cell recordings, rapid temperature changes within a few milliseconds were imposed. This method allowed for the measurement of current amplitudes immediately before and after a temperature jump, from which the ratios of these currents (Iratio) were determined. The use of Iratio for evaluating the temperature dependence minimized the contributions of factors other than permeation. Temperature jumps of various degrees (ΔT, −15 to 15°C) were applied over a wide temperature range (4–49°C), and the Q10s for the proton currents were evaluated from the Iratios. Q10 exhibited a high temperature dependence, varying from 2.2 at 10°C to 1.3 at 40°C. This implies that processes with different temperature dependencies underlie the observed Q10. A novel resistivity pulse method revealed that the access resistance with its low temperature dependence predominated in high temperature ranges. The measured temperature dependence of Q10 was decomposed into Q10 of the channel and of the access resistances. Finally, the Q10 for proton permeation through the voltage-gated proton channel itself was calculated and found to vary from 2.8 at 5°C to 2.2 at 45°C, as expected for an activation enthalpy of 64 kJ/mol. The thermodynamic features for proton permeation through proton-selective channels were discussed for the underlying mechanism. PMID:19720960

  7. Evaluation of Oxidation and Hydrogen Permeation of Al Containing Duplex Stainless Steels

    SciTech Connect

    Adams, Thad M.; Korinko, Paul; Duncan, Andrew

    2005-06-17

    As the National Hydrogen Economy continues to develop and evolve the need for structural materials that can resist hydrogen assisted degradation will become critical. To date austenitic stainless steel materials have been shown to be mildly susceptible to hydrogen attack which results in lower mechanical and fracture strengths. As a result, hydrogen permeation barrier coatings are typically applied to these steel to retard hydrogen ingress. The focal point of the reported work was to evaluate the potential for intentional alloying of commercial 300-series stainless steels to promote hydrogen permeation resistant oxide scales. Previous research on the Cr- and Fe-oxide scales inherent to 300-series stainless steels has proven to be inconsistent in effecting permeation resistance. The approach undertaken in this research was to add aluminum to the 300-series stainless steels in an attempt to promote a pure Al-oxide or and Al-rich oxide scale. Aloxide had been previously demonstrated to be an effective hydrogen permeation barrier. Results for 304L and 347H alloys doped with Al in concentration from 0.5-3.0 wt% with respect to oxidation kinetic studies, cyclic oxidation and characterization of the oxide scale chemistry are reported herein. Gaseous hydrogen permeation testing of the Al-doped alloys in both the unoxidized and oxidized (600 C, 30 mins) conditions are reported. A critical finding from this work is that at concentration as low as 0.5 wt% Al, the Al stabilizes the ferrite phase in these steels thus producing duplex austenitic-ferritic microstructures. As the Al-content increases the amount of measured ferrite increases thus resulting in hydrogen permeabilities more closely resembling ferritic steels.

  8. Lyophilized phytosomal nanocarriers as platforms for enhanced diosmin delivery: optimization and ex vivo permeation

    PubMed Central

    Freag, May S; Elnaggar, Yosra SR; Abdallah, Ossama Y

    2013-01-01

    Diosmin (DSN) is an outstanding phlebotonic flavonoid with a tolerable potential for the treatment of colon and hepatocellular carcinoma. Being highly insoluble, DSN bioavailability suffers from high inter-subject variation due to variable degrees of permeation. This work endeavored to develop novel DSN loaded phytosomes in order to improve drug dissolution and intestinal permeability. Three preparation methods (solvent evaporation, salting out, and lyophilization) were compared. Nanocarrier optimization encompassed different soybean phospholipid (SPC) types, different solvents, and different DSN:SPC molar ratios (1:1, 1:2, and 1:4). In vitro appraisal encompassed differential scanning calorimetry, infrared spectroscopy, particle size, zeta potential, polydispersity index, transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed under sink versus non-sink conditions. Ex vivo intestinal permeation studies were performed on rats utilizing noneverted sac technique and high-performance liquid chromatography analysis. The results revealed lyophilization as the optimum preparation technique using SPC and solvent mixture (Dimethyl sulphoxide:t-butylalchol) in a 1:2 ratio. Complex formation was contended by differential scanning calorimetry and infrared data. Optimal lyophilized phytosomal nanocarriers (LPNs) exhibited the lowest particle size (316 nm), adequate zeta-potential (−27 mV), and good in vitro stability. Well formed, discrete vesicles were revealed by transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed. LPNs demonstrated significant enhancement in DSN dissolution compared to crude drug, physical mixture, and generic and brand DSN products. Permeation studies revealed 80% DSN permeated from LPNs via oxygenated rat intestine compared to non-detectable amounts from suspension. In this study, LPNs (99% drug loading) could be successfully

  9. Permeation of gasoline, diesel, bioethanol (E85), and biodiesel (B20) fuels through six glove materials.

    PubMed

    Chin, Jo-Yu; Batterman, Stuart A

    2010-07-01

    Biofuels and conventional fuels differ in terms of their evaporation rates, permeation rates, and exhaust emissions, which can alter exposures of workers, especially those in the fuel refining and distribution industries. This study investigated the permeation of biofuels (bioethanol 85%, biodiesel 20%) and conventional petroleum fuels (gasoline and diesel) through gloves used in occupational settings (neoprene, nitrile, and Viton) and laboratories (latex, nitrile, and vinyl), as well as a standard reference material (neoprene sheet). Permeation rates and breakthrough times were measured using the American Society for Testing and Materials F739-99 protocol, and fuel and permeant compositions were measured by gas chromatography/mass spectrometry. In addition, we estimated exposures for three occupational scenarios and recommend chemical protective clothing suitable for use with motor fuels. Permeation rates and breakthrough times depended on the fuel-glove combination. Gasoline had the highest permeation rate among the four fuels. Bioethanol (85%) had breakthrough times that were two to three times longer than gasoline through neoprene, nitrile Sol-Vex, and the standard reference materials. Breakthrough times for biodiesel (20%) were slightly shorter than for diesel for the latex, vinyl, nitrile examination, and the standard neoprene materials. The composition of permeants differed from neat fuels, e.g., permeants were significantly enriched in the lighter aromatics including benzene. Viton was the best choice among the tested materials for the four fuels tested. Among the scenarios, fuel truck drivers had the highest uptake via inhalation based on the personal measurements available in the literature, and gasoline station attendants had highest uptake via dermal exposure if gloves were not worn. Appropriate selection and use of gloves can protect workers from dermal exposures; however, current recommendations from the National Institute for Occupational Safety and

  10. Permeation tests of glove and clothing materials against sensitizing chemicals using diphenylmethane diisocyanate as an example.

    PubMed

    Mäkelä, Erja A; Henriks-Eckerman, Maj-Len; Ylinen, Katriina; Vuokko, Aki; Suuronen, Katri

    2014-08-01

    Diphenylmethane diisocyanate (MDI) is a sensitizing chemical that can cause allergic contact dermatitis and asthma. Protective gloves and clothing are necessary to prevent skin exposure. Breakthrough times are used for the selection of chemical protective gloves and clothing. In the EN 374-3:2003 European standard, breakthrough time is defined as the time in which the permeation reaches the rate of 1.0 µg min(-1) cm(-2) through the material. Such breakthrough times do not necessarily represent safe limits for sensitizing chemicals. We studied the permeation of 4,4'-MDI through eight glove materials and one clothing material. The test method was derived from the EN 374-3 and ASTM F 739 standards. All measured permeation rates were below 0.1 µg min(-1) cm(-2), and thus, the breakthrough times for all the tested materials were over 480min, when the definitions of EN 374-3 and ASTM F 739 for the breakthrough time were used. Based on the sensitizing capacity of MDI, we concluded that a cumulative permeation of 1.0 µg cm(-2) should be used as the end point of the breakthrough time determination for materials used for protection against direct contact with MDI. Using this criterion for the breakthrough time, seven tested materials were permeated in <480min (range: 23-406min). Affordable chemical protective glove materials that had a breakthrough time of over 75min were natural rubber, thick polyvinylchloride, neoprene-natural rubber, and thin and thick nitrile rubber. We suggest that the current definitions of breakthrough times in the standard requirements for protective materials should be critically evaluated as regards MDI and other sensitizing chemicals, or chemicals highly toxic via the skin. PMID:24936578

  11. Lyophilized phytosomal nanocarriers as platforms for enhanced diosmin delivery: optimization and ex vivo permeation.

    PubMed

    Freag, May S; Elnaggar, Yosra S R; Abdallah, Ossama Y

    2013-01-01

    Diosmin (DSN) is an outstanding phlebotonic flavonoid with a tolerable potential for the treatment of colon and hepatocellular carcinoma. Being highly insoluble, DSN bioavailability suffers from high inter-subject variation due to variable degrees of permeation. This work endeavored to develop novel DSN loaded phytosomes in order to improve drug dissolution and intestinal permeability. Three preparation methods (solvent evaporation, salting out, and lyophilization) were compared. Nanocarrier optimization encompassed different soybean phospholipid (SPC) types, different solvents, and different DSN:SPC molar ratios (1:1, 1:2, and 1:4). In vitro appraisal encompassed differential scanning calorimetry, infrared spectroscopy, particle size, zeta potential, polydispersity index, transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed under sink versus non-sink conditions. Ex vivo intestinal permeation studies were performed on rats utilizing noneverted sac technique and high-performance liquid chromatography analysis. The results revealed lyophilization as the optimum preparation technique using SPC and solvent mixture (Dimethyl sulphoxide:t-butylalchol) in a 1:2 ratio. Complex formation was contended by differential scanning calorimetry and infrared data. Optimal lyophilized phytosomal nanocarriers (LPNs) exhibited the lowest particle size (316 nm), adequate zeta-potential (-27 mV), and good in vitro stability. Well formed, discrete vesicles were revealed by transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed. LPNs demonstrated significant enhancement in DSN dissolution compared to crude drug, physical mixture, and generic and brand DSN products. Permeation studies revealed 80% DSN permeated from LPNs via oxygenated rat intestine compared to non-detectable amounts from suspension. In this study, LPNs (99% drug loading) could be successfully

  12. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  13. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  14. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  15. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  16. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  17. Rheological characterization and permeation behavior of poloxamer 407-based systems containing 5-aminolevulinic acid for potential application in photodynamic therapy.

    PubMed

    van Hemelrijck, Carlos; Müller-Goymann, Christel C

    2012-11-01

    Topical application of 5-aminolevulinic acid (ALA) in photodynamic therapy is of great interest because of avoiding systemic side effects with such an easy way of application. However, due to ALA's high polarity its dermal bioavailability is rather limited and thus, permeation enhancement of this active is of major interest in research. In a previous study, a semisolid poloxamer 407-based (POX), five-component system ("thermogel") was developed for permeation enhancement of ALA across isolated human stratum corneum. In the present study, five-component systems of systematically varied compositions were investigated both rheologically and in terms of permeation enhancement. The five-component systems contained water, a fixed combination of 1:1 of isopropyl alcohol (IPA) and dimethyl isosorbide (DMIS) and a fixed ratio of 4:1 of POX to propylene glycol dicaprylocaprate (MIG). Rheological characterization showed that complex viscosity depended on IPA/DMIS and POX/MIG content. The gelation temperature (GT) was strongly influenced by interactions between MIG, IPA and DMIS. Regarding permeation behavior, several systems showing better permeation fluxes than the original "thermogel" were identified. Surprisingly, permeation flux did not inversely correlate with the complex viscosity, showing that permeation behavior may depend on a variety of further physicochemical characteristics including individual composition and microstructure of the respective formulation. PMID:22898092

  18. In silico modelling of permeation enhancement potency in Caco-2 monolayers based on molecular descriptors and random forest.

    PubMed

    Welling, Søren H; Clemmensen, Line K H; Buckley, Stephen T; Hovgaard, Lars; Brockhoff, Per B; Refsgaard, Hanne H F

    2015-08-01

    Structural traits of permeation enhancers are important determinants of their capacity to promote enhanced drug absorption. Therefore, in order to obtain a better understanding of structure-activity relationships for permeation enhancers, a Quantitative Structural Activity Relationship (QSAR) model has been developed. The random forest-QSAR model was based upon Caco-2 data for 41 surfactant-like permeation enhancers from Whitehead et al. (2008) and molecular descriptors calculated from their structure. The QSAR model was validated by two test-sets: (i) an eleven compound experimental set with Caco-2 data and (ii) nine compounds with Caco-2 data from literature. Feature contributions, a recent developed diagnostic tool, was applied to elucidate the contribution of individual molecular descriptors to the predicted potency. Feature contributions provided easy interpretable suggestions of important structural properties for potent permeation enhancers such as segregation of hydrophilic and lipophilic domains. Focusing on surfactant-like properties, it is possible to model the potency of the complex pharmaceutical excipients, permeation enhancers. For the first time, a QSAR model has been developed for permeation enhancement. The model is a valuable in silico approach for both screening of new permeation enhancers and physicochemical optimisation of surfactant enhancer systems. PMID:26004819

  19. Pretreatment effects of moxibustion on the skin permeation and skin and muscle concentrations of salicylate in rats.

    PubMed

    Cao, Dianxiu; Tazawa, Yuko; Ishii, Hiroshi; Todo, Hiroaki; Sugibayashi, Kenji

    2011-04-01

    The effect of moxibustion on the in vitro and in vivo skin permeation of salicylate was evaluated in rats. First, the effect of moxibustion pretreatment on the elimination pharmacokinetics of salicylate after i.v. injection in rats was determined: no clear difference was observed in the plasma profiles of salicylate (SA) with or without moxibustion pretreatment. However, much higher skin and muscle concentrations of salicylate were observed after its i.v. injection. Next, an in vitro skin permeation study of SA was performed after moxibustion pretreatment. Moxibustion pretreatment increased the skin permeation of SA, and the extent of the increase in SA skin permeation was related to the strength of moxibustion ignition. More intense treatments produced higher skin permeation. A similar enhancement effect on the skin permeation of SA was observed in in vivo studies. Interestingly, the skin/plasma and muscle/plasma ratios of SA were markedly increased by moxibustion pretreatment. These results were due to the induction of enhanced skin permeation and lower clearance into the cutaneous vessels by moxibustion ignition. Combination treatment involving moxibustion and the topical application of drugs such as NSAID may be useful for increasing local pharmaceutical effects by enhancing the drug concentration in the skin and muscle underneath the topical application site. PMID:21256938

  20. Permeation of hair dye ingredients, p-phenylenediamine and aminophenol isomers, through protective gloves.

    PubMed

    Lee, Hsiao-Shu; Lin, Yu-Wen

    2009-04-01

    Skin irritation and contact allergies are skin disorders common to hairdressers. The predominant oxidative hair dye components, such as p-phenylenediamine (PPD) and aminophenol isomers, can cause contact dermatitis. Use of protective gloves can prevent dermal contact with skin irritants. This study investigates the permeation behaviors of p-aminophenol (PAP), m-aminophenol (MAP), o-aminophenol (OAP) and PPD in single and mixed challenge solutions with disposable natural rubber latex (NRL) gloves, disposable polyvinylchloride (PVC) gloves and neoprene (NP) gloves. The challenge solutions were 4% PPD (w/v), 3% OAP (w/v), 2% PAP (w/v) and 2% MAP (w/v) in ethanol or 12% hydrogen peroxide solutions. The cocktail solutions of the four chemicals were also tested. An American Society for Testing and Materials type permeation cell, ethanol liquid collection and gas chromatography-flame ionization detection of samples taken from the collection medium every 10 min facilitated determination of breakthrough times (BTs), cumulative permeated masses and steady-state permeation rates (SSPRs). Experiments were 4 h long for the NRL and PVC gloves and 8 h for NP gloves. No chemicals tested broke through the NP gloves when exposed for 8 h. In the ethanol solution, PPD and OAP started breaking through the PVC gloves at 40 min. The SSPRs of PVC gloves were higher than those for NRL gloves in all challenge conditions for both single chemicals and mixtures. No tested chemicals in hydrogen peroxide solutions permeated the gloves during the 4-h tests. The chemical composition of the challenge solution was a main effecter of BTs and SSPRs for the NRL glove. For disposable PVC gloves, the main factors of BTs were molecular size [molar volume (MV)] and polarity (logK(ow)), and the primary factors of SSPRs were concentration, MV and logK(ow). In conclusion, disposable NRL gloves and disposable PVC gloves should not be used repeatedly for handling the hair dye products. Hydrogen peroxide did not

  1. Glove permeation by semiconductor processing mixtures containing glycol-ether derivatives.

    PubMed

    Zellers, E T; Ke, H Q; Smigiel, D; Sulewski, R; Patrash, S J; Han, M W; Zhang, G Z

    1992-02-01

    Results of permeation tests of several glove materials challenged with semiconductor processing formulations containing glycolether derivatives are described. Commercial glove samples of nitrile rubber (Edmont), natural rubber (Edmont and Baxter), butyl rubber (North), PVC Baxter), a natural rubber/neoprene/nitrile blend (Pioneer), and a natural rubber/neoprene blend (Playtex) were tested according to the ASTM F739-85 permeation test method (open-loop configuration). The liquid formulations examined included a positive photoresist thinner containing 2-ethoxyethyl acetate (2-EEA), n-butyl acetate, and xylene; a positive photoresist containing 2-EEA, n-butyl acetate, xylene, polymer resins, and photoactive compounds; a negative photoresist containing 2-methoxyethanol (2-ME), xylene, and cyclized poly(isoprene); and pure 2-methoxyethyl acetate (2-MEA), which is the solvent used in a commercial electron-beam resist. With the exception of the negative photoresist, butyl rubber provided the highest level of protection against the solvent mixtures tested, with no breakthrough observed after 4 hr of continuous exposure at 25 degrees C. Nitrile rubber provided the highest level of protection against the negative photoresist and reasonably good protection against initial exposure to the other solvent mixtures. Gloves consisting of natural rubber or natural rubber blends provided less protection against the mixtures than either nitrile or butyl rubber. For most of the glove samples, permeation of the glycol-ether derivatives contained in the mixtures was faster than that predicted from the permeation of the pure solvents. Increasing the exposure temperature from 25 to 37 degrees C did not significantly affect the performance of the butyl rubber glove. For the other gloves, however, exposures at 37 degrees C resulted in decreases in breakthrough times of 25-75% and increases in steady-state permeation rates of 80-457% relative to values obtained at 25 degrees C. Repeated

  2. Effect of phosphatidylserine on the basal and GABA-activated Cl- permeation across single nerve membranes from rabbit Deiters' neurons

    SciTech Connect

    Rapallino, M.V.; Cupello, A.; Mainardi, P.; Besio, G.; Loeb, C.W. )

    1990-06-01

    The permeation of labeled Cl- ions across single plasma membranes from Deiters' neurons has been studied in the presence of various concentrations of phosphatidylserine (PS) on their extracellular side. PS reduces significantly basal Cl- permeation only at 10(-5) M on the membrane exterior. No effect was found at other concentrations. GABA activable 36Cl- permeation is heavily reduced and almost abolished at 10(-11) - 10(-5) M phosphatidylserine. This exogenous phosphatidylserine effect is difficult to interpret in relation to the function of the endogenous phospholipid. However, it may be involved in the epileptogenic effect in vivo of exogenous phosphatidylserine administration to rats.

  3. Probing Toluene and Ethylbenzene Stable Glass Formation using Inert Gas Permeation

    SciTech Connect

    Smith, R. Scott; May, Robert A.; Kay, Bruce D.

    2015-09-01

    Inert gas permeation is used to investigate the formation of stable glasses of toluene and ethylbenzene. The effect of deposition temperature (Tdep) on the kinetic stability of the vapor deposited glasses is determined using Kr desorption spectra from within sandwich layers of either toluene or ethylbenzene. The results for toluene show that the most stable glass is formed at Tdep = 0.92 Tg, although glasses with a kinetic stability within 50% of the most stable glass were found with deposition temperatures from 0.85 to 0.95 Tg. Similar results were found for ethylbenzene, which formed its most stable glass at 0.91 Tg and formed stable glasses from 0.81 to 0.96 Tg. These results are consistent with recent calorimetric studies and demonstrate that the inert gas permeation technique provides a direct method to observe the onset of molecular translation motion that accompanies the glass to supercooled liquid transition.

  4. Photocontrol of ion permeation in lipid vesicles with (bola)amphiphilic spirooxazines.

    PubMed

    Kandasamy, Yamuna S; Cai, Jianxin; Ottaviano, John G; Smith, Kelti A; Williams, Ashley N; Moore, Jarod; Louis, Kristen M; Selzler, Lindsay; Beler, Alisha; Okwuonu, Tobechi; Murphy, R Scott

    2016-01-01

    Three (bola)amphiphilic spirooxazines have been synthesized and their photochromism has been characterized. The large biphotochromic structure of 2 significantly affects its conformational flexibility and the rate constants for thermal ring closure are particularly dependent on the lipid phase state. Two comprehensive ion permeation studies were performed to examine the effect of spirooxazine inclusion and isomerization on membrane permeability. In all cases, the open-ring isomers of these spirooxazines are more disruptive in bilayer membranes than their closed-ring isomers. Further, the rate of ion permeation and net release are highly dependent on the lipid bilayer phase state and the relative position of the photochromic moiety in the bilayer membrane. Moreover, the difference in potassium ion permeability under UV and visible irradiation is more pronounced than previously reported photoresponsive membrane disruptors with reversible photocontrols. PMID:26507583

  5. Diacetyl and acetoin production from whey permeate using engineered Lactobacillus casei.

    PubMed

    Nadal, Inmaculada; Rico, Juan; Pérez-Martínez, Gaspar; Yebra, María J; Monedero, Vicente

    2009-09-01

    The capability of Lactobacillus casei to produce the flavor-related compounds diacetyl and acetoin from whey permeate has been examined by a metabolic engineering approach. An L. casei strain in which the ilvBN genes from Lactococcus lactis, encoding acetohydroxyacid synthase, were expressed from the lactose operon was mutated in the lactate dehydrogenase gene (ldh) and in the pdhC gene, which codes for the E2 subunit of the pyruvate dehydrogenase complex. The introduction of these mutations resulted in an increased capacity to synthesize diacetyl/acetoin from lactose in whey permeate (1,400 mg/l at pH 5.5). The results showed that L. casei can be manipulated to synthesize added-value metabolites from dairy industry by-products. PMID:19609583

  6. Biofilm increases permeate quality by organic carbon degradation in low pressure ultrafiltration.

    PubMed

    Chomiak, A; Traber, J; Morgenroth, E; Derlon, N

    2015-11-15

    We investigated the influence of biofouling of ultrafiltration membranes on the removal of organic model foulants and ultimately on the quality of permeate. Gravity Driven Membrane ultrafiltration (GDM) membrane systems were operated with modified river water during five weeks without control of the biofilm formation. Three GDM systems were studied: two systems with biofilms exposed to (A) variable or (B) constant load of organic foulants, and (C) one system operated without biofilm and exposed to constant foulant loading. Biodegradable dextran or non-biodegradable polystyrene sulfonate model foulants were tested. Substrate biodegradability was confirmed by Size Exclusion Chromatography (SEC) and by degradation batch tests (D). The GDM systems (A) and (B) were fed with pre-filtered river water supplemented with dextran (Dex) of 1, 150 or 2000 kDa, or polystyrene sulfonate (PSS) of 1 or 80 kDa at concentrations of 2-3.5 mgC L(-1). In exp. (C) the feed water consisted of deionized water with 25 mgC L(-1) of either PSS 1, 80 kDa or Dex 2000 kDa. The biofilm formation on UF membrane surfaces controlled the foulant permeation and thus the permeate quality. Biofilms exposed to continuous foulant loading (exp. B) degraded low molecular weight (LMW) biodegradable foulants (1 kDa Dex), which improved the permeate quality. For high molecular weight (HMW) substrates (150, 2000 kDa Dex), the improvement of the permeate quality was observed after 7 days of biofilm formation, and resulted from the foulant hydrolysis followed by degradation. For non-biodegradable foulants, an improvement of 20% of the retention was observed for the polystyrene (1, 80 kDa PSS) due to the presence of biofilms on membrane surfaces. For variable foulant loading (exp. A) the biofilms hydrolysed the large biodegradable foulants but did not degraded them fully, which resulted a deterioration of the permeate quality (except for the LMW dextran (1 kDa) that was fully degraded). Overall, the "biofilm

  7. Permeation of topically applied Magnesium ions through human skin is facilitated by hair follicles.

    PubMed

    Chandrasekaran, Navin Chandrakanth; Sanchez, Washington Y; Mohammed, Yousuf H; Grice, Jeffrey E; Roberts, Michael S; Barnard, Ross T

    2016-06-01

    Magnesium is an important micronutrient essential for various biological processes and its deficiency has been linked to several inflammatory disorders in humans. Topical magnesium delivery is one of the oldest forms of therapy for skin diseases, for example Dead Sea therapy and Epsom salt baths. Some anecdotal evidence and a few published reports have attributed amelioration of inflammatory skin conditions to the topical application of magnesium. On the other hand, transport of magnesium ions across the protective barrier of skin, the stratum corneum, is contentious. Our primary aim in this study was to estimate the extent of magnesium ion permeation through human skin and the role of hair follicles in facilitating the permeation. Upon topical application of magnesium solution, we found that magnesium penetrates through human stratum corneum and it depends on concentration and time of exposure. We also found that hair follicles make a significant contribution to magnesium penetration. PMID:27624531

  8. Surface effects on hydrogen permeation through Ti-14Al-21Nb alloy

    NASA Technical Reports Server (NTRS)

    Sankaran, Sandara N.; Outlaw, Ronald A.; Clark, Ronald K.

    1991-01-01

    Hydrogen transport through Ti-14Al-21Nb (wt percent) alloy is measured using ultrahigh vacuum permeation techniques over the temperature range of 500 to 900 C and hydrogen pressure range of 0.25 to 10 torr. Hydrogen permeability through the alloy can be described through two different mechanisms depending on th temperature of exposure. In the 675 to 900 C range, the process is diffusion-limited: the permeability has a weak temperature dependence, but the diffusivity has a strong temperature dependence. Below 675 C, the permeation rate of hydrogen is very sensitive to surface controlled processes such as the formation of a barrier layer from contaminants. A physical model explaining the role of surface films on the transport of hydrogen through Ti-14Al-21Nb alloy was described.

  9. Free volume and gas permeation in ion-exchanged forms of the Nafion® membrane

    NASA Astrophysics Data System (ADS)

    Mohamed, Hamdy F. M.; Kobayashi, Y.; Kuroda, C. S.; Ohira, A.

    2010-04-01

    Variations of free volume and gas permeability of the Nafion® membrane upon ion-exchange of H+ with Cs+ or Pt2+ was studied as a function of temperature. Free volume was quantified using the positron annihilation lifetime technique. Our results showed that the free volume (VFV,Ps) of the dried membrane is enlarged by thermal expansion. It was found that the ion-exchange significantly expands the free volume and at the same time decreases the permeabilities of O2 and H2. Good linear correlations between the logarithm of permeabilities of O2 and H2 at different temperatures and 1/VFV,Ps for the ion-exchanged forms of Nafion® in the dried state suggest an important role played by the free volume in gas permeation. Considerable downward deviation of the correlations for the ion-exchanged ionomers from the H+-form suggested the importance of polymer stiffening in gas permeation.

  10. Gas-phase hydrogen permeation through alpha-titanium - Surface film and dimensional effects

    NASA Technical Reports Server (NTRS)

    Shah, K. K.; Johnson, D. L.

    1982-01-01

    The process of hydrogen transport through alpha-Ti involves simultaneous diffusion and phase boundary reactions at both surfaces, with the relative effect on each surface depending on the extent of surface contamination as well as the physical dimensions of the titanium membrane used. It is shown by the present study that hydrogen permeation in commercially pure alpha-Ti increases exponentially with temperature and is dependent on the first power of the input pressure, whether the surface is as-polished, preoxidized or prenitrided. Permeation decreases in the case of the as-polished condition if nitride or oxide films are formed at the surface in contact with source hydrogen, while increasing slightly for the same condition if such films are formed at the hydrogen exit surface.

  11. Contaminant Permeation in the Ionomer-Membrane Water Processor (IWP) System

    NASA Technical Reports Server (NTRS)

    Kelsey, Laura K.; Finger, Barry W.; Pasadilla, Patrick; Perry, Jay

    2016-01-01

    The Ionomer-membrane Water Processor (IWP) is a patented membrane-distillation based urine brine water recovery system. The unique properties of the IWP membrane pair limit contaminant permeation from the brine to the recovered water and purge gas. A paper study was conducted to predict volatile trace contaminant permeation in the IWP system. Testing of a large-scale IWP Engineering Development Unit (EDU) with urine brine pretreated with the International Space Station (ISS) pretreatment formulation was then conducted to collect air and water samples for quality analysis. Distillate water quality and purge air GC-MS results are presented and compared to predictions, along with implications for the IWP brine processing system.

  12. Simulated gastrointestinal digestion, intestinal permeation and plasma protein interaction of white, green, and black tea polyphenols.

    PubMed

    Tenore, Gian Carlo; Campiglia, Pietro; Giannetti, Daniela; Novellino, Ettore

    2015-02-15

    The gastrointestinal digestion, intestinal permeation, and plasma protein interaction of polyphenols from a single tea cultivar at different stages of processing (white, green, and black teas) were simulated. The salivary phase contained 74.8-99.5% of native polyphenols, suggesting potential bioavailability of significant amounts of antioxidants through the oral mucosal epithelium that might be gastric sensitive and/or poorly absorbed in the intestine. White tea had the highest content and provided the best intestinal bioaccessibility and bioavailability for catechins. Since most of native catechins were not absorbed, they were expected to accumulate in the intestinal lumen where a potential inhibition capacity of cellular glucose and cholesterol uptake was assumed. The permeated catechins (approximately, 2-15% of intestinal levels) significantly bound (about 37%) to plasma HDLs, suggesting a major role in cholesterol metabolism. White tea and its potential nutraceuticals could be effective in the regulation of plasma glucose and cholesterol levels. PMID:25236233

  13. Enhanced Permeation of a Hydrophobic Fluid through Particles with Hydrophobic and Hydrophilic Patterned Surfaces

    PubMed Central

    Zhang, Renliang; Xu, Yousheng; Wen, Binghai; Sheng, Nan; Fang, Haiping

    2014-01-01

    The wetting properties of solid surfaces are significant in oil/gas and liquid displacement processes. It is difficult for hydrophobic fluids to permeate channels filled with hydrophilic particles and an aqueous phase, and this is thought to be the primary cause of low yields in low permeability reservoir operations. Using three-dimensional lattice Boltzmann simulations, we show that particles with hydrophobic and hydrophilic patterned surfaces can greatly improve hydrophobic fluid permeation. Specifically, a hydrophobic fluid can easily access micro-channels in the hydrophobic regions, which extend rapidly even to the hydrophilic regions and accelerate hydrophobic fluid escape. This work enriches understanding of multiphase flow in porous media at the pore scale and fracture conductivity and is expected to have great significance in the exploitation of low permeability reservoirs and shale gas. PMID:25033709

  14. Characterization of Thin Film Polymers Through Dynamic Mechanical Analysis and Permeation

    NASA Technical Reports Server (NTRS)

    Herring, Helen

    2003-01-01

    Thin polymer films are being considered, as candidate materials to augment the permeation resistance of cryogenic hydrogen fuel tanks such as would be required for future reusable launch vehicles. To evaluate performance of candidate films after environmental exposure, an experimental study was performed to measure the thermal/mechanical and permeation performance of six, commercial-grade materials. Dynamic storage modulus, as measured by Dynamic Mechanical Analysis, was found over a range of temperatures. Permeability, as measured by helium gas diffusion, was found at room temperature. Test data was correlated with respect to film type and pre-test exposure to moisture, elevated temperature, and cryogenic temperature. Results indicated that the six films were comparable in performance and their resistance to environmental degradation.

  15. Tritium permeation through characterized films on Type 304L stainless steel

    SciTech Connect

    Kallas, A.J.; Rising, T.L.; Childs, E.L.; Thomas, R.L.

    1987-07-24

    Rocky Flats is looking for an optimum method for surface treating 304L stainless steel to increase its resistance to tritium permeation. Selected surface treatments were applied to 304L samples. One set of samples was shipped to the Rockwell Corporate Science Center for alternate characterization analysis. Another set was sent to Los Alamos National Laboratory for tritium exposure and ion beam spectrographic analysis. The Science Center performed the following analyses: ellipsometry, contact potential, photoelectron emission, surface energy, surface activation, cathodic polarization, electrochemical impedance, and open-circuit potential. Excellent correlation was found between type of treatment and surface activation and electrochemical impedance. Results of the Science Center tests correlated well with actual tritium permeation measurements made at Los Alamos. 8 refs., 8 figs., 1 tab.

  16. Methyl isocyanate liquid and vapor permeation through selected respirator diaphragms and chemical protective clothing

    SciTech Connect

    Berardinelli, S.P.; Moyer, E.S.

    1987-04-01

    Initially, a study was undertaken to evaluate selected chemical protective clothing suitable for use by emergency response personnel confronted with methyl isocyanate (MIC). Twenty-two chemical protective clothing materials were tested against liquid methyl isocyanate. Chemical permeation breakthrough times for these clothing materials demonstrate that only one of these garments can be considered as a candidate material against liquid MIC. In a subsequent study, three chemical protective clothing materials were evaluated against approximately 800 ppm MIC vapor. Chemical permeation breakthrough times demonstrate that these materials can be considered candidate materials. A final study tested self-contained breathing apparatus (SCBA) diaphragms. Four SCBA diaphragms were tested and all experienced rapid breakthrough when exposed to liquid MIC. Next, three SCBA diaphragms were exposed to approximately 800 ppm MIC vapor. The data demonstrate that the SCBA should be worn inside a total encapsulating suit.

  17. Investigation on Large Molecule Permeation through Liposome Lipid Bilayer Induced by Microplasma Irradiation

    NASA Astrophysics Data System (ADS)

    Nagaiwa, Hidenori; Aibara, Daijiro; Ikeda, Yoshihisa; Motomura, Hideki; Kido, Yugo; Satoh, Susumu; Tachibana, Kunihide; Jinno, Masahumi

    2015-09-01

    The authors have been developing a novel gene transfection method using microplasma irradiation. In order to clarify the mechanism of large molecule permeation process through the lipid bilayer, plasma induced outflow of hydrophilic fluorescent dye molecules, which were encapsulated in the liposome, was observed. By microplasma irradiation on the liposome suspension, the dyes flowed out from the inside of the liposomes. The outflow of the dyes was enhanced by longer plasma irradiation time. Investigation of the outflow mechanism, i.e. permeation enhancement of the lipid bilayer or burst of the liposome, is under progress. This work was partly supported by JSPS KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas (Number 25108509,15H00896) and a grant from Ehime University.

  18. Reducing the natural color of membrane bioreactor permeate with activated carbon or ozone.

    PubMed

    Abegglen, Christian; Joss, Adriano; Boehler, Marc; Buetzer, Simone; Siegrist, Hansruedi

    2009-01-01

    The suitability of two membrane bioreactors for on-site wastewater treatment and reuse in Switzerland was investigated. The treated wastewater was used for toilet flushing and gardening, with water recycling rates of 30% (single family house) and almost 100% (toilets in a cable car station) respectively. Due to the recycling, an increase in a natural yellowish-brown color was observed, leading to double flushing of the toilets, higher cleaning requirements and increased permeate production. Color removal with ozone, powdered (PAC) and granulated (GAC) activated carbon was assessed in laboratory and field experiments. PAC was added directly into the MBR, whereas ozonation and GAC were applied to the permeate. The dosage of ozone or activated carbon depended on the recycling rate and color intensity. If color removal is necessary, PAC is the option best suited to small treatment plants, with a requirement of 30-50 g m(-3) for 30% and 100 g m(-3) for 100% water recycling. PMID:19587413

  19. Water Permeation Across Biological Membranes: Mechanism and Dynamics of Aquaporin-1 and GlpF

    NASA Astrophysics Data System (ADS)

    de Groot, Bert L.; Grubmüller, Helmut

    2001-12-01

    ``Real time'' molecular dynamics simulations of water permeation through human aquaporin-1 (AQP1) and the bacterial glycerol facilitator GlpF are presented. We obtained time-resolved, atomic-resolution models of the permeation mechanism across these highly selective membrane channels. Both proteins act as two-stage filters: Conserved fingerprint [asparagine-proline-alanine (NPA)] motifs form a selectivity-determining region; a second (aromatic/arginine) region is proposed to function as a proton filter. Hydrophobic regions near the NPA motifs are rate-limiting water barriers. In AQP1, a fine-tuned water dipole rotation during passage is essential for water selectivity. In GlpF, a glycerol-mediated ``induced fit'' gating motion is proposed to generate selectivity for glycerol over water.

  20. Water permeation and electrical properties of pottants, backings, and pottant/backing composites

    NASA Technical Reports Server (NTRS)

    Orehotsky, J.

    1986-01-01

    It is reported that the interface between plastic film back covers and ethylene vinyl acetates (EVA) or polyvinyl butyral (PVB) in photovoltaic modules can influence water permeation, and electrial properties of the composites such as leakage current and dielectric constant. The interface can either be one of two dissimilar materials in physical contact with no intermixing, or the interface can constitute a thin zone which is an interphase of the two materials having a gradient composition from one material to the other. The former condition is described as a discrete interface. A discrete interface model was developed to predict water permeation, dielectric strength, and leakage current for EVA, ethylene methyl acrylate (EMA), and PVB coupled to Tedlar and mylar films. Experimental data was compared with predicted data.

  1. Determination of alkylamine permeation through protective gloves using aliphatic amine pads.

    PubMed

    Vo, E; Berardinelli, S P

    1999-12-01

    A quantitative study of alkylamine permeation through a glove material using Permea-Tec aliphatic amine pads, used for the detection of chemical breakthrough of protective clothing, was performed for triethylamine following a microwave-extraction process and gas chromatographic analysis. Triethylamine exhibited > 99% adsorption on the pads at a spiking level of 729 ng (1.0 ml). Triethylamine showed recoveries from 63 to 90% (RSD < or = 5%) over the range 0.2-1.0 ml (146-729 ng) applied to pads. The ASTM F739 standard and direct permeability testing procedures were used to determine breakthrough times for five protective glove materials using triethylamine as a challenge chemical. Breakthrough times for six protective gloves were determined ranging from 40 s to > 4 h. The quantitative concentration of triethylamine on the pads following permeation through the gloves was also determined, ranging from 101 to 103 ng cm-2 (382-386 ng per pad). PMID:11529186

  2. Enhanced permeation of a hydrophobic fluid through particles with hydrophobic and hydrophilic patterned surfaces.

    PubMed

    Zhang, Renliang; Xu, Yousheng; Wen, Binghai; Sheng, Nan; Fang, Haiping

    2014-01-01

    The wetting properties of solid surfaces are significant in oil/gas and liquid displacement processes. It is difficult for hydrophobic fluids to permeate channels filled with hydrophilic particles and an aqueous phase, and this is thought to be the primary cause of low yields in low permeability reservoir operations. Using three-dimensional lattice Boltzmann simulations, we show that particles with hydrophobic and hydrophilic patterned surfaces can greatly improve hydrophobic fluid permeation. Specifically, a hydrophobic fluid can easily access micro-channels in the hydrophobic regions, which extend rapidly even to the hydrophilic regions and accelerate hydrophobic fluid escape. This work enriches understanding of multiphase flow in porous media at the pore scale and fracture conductivity and is expected to have great significance in the exploitation of low permeability reservoirs and shale gas. PMID:25033709

  3. Permeation studies of novel terbinafine formulations containing hydrophobins through human nails in vitro.

    PubMed

    Vejnovic, Ivana; Huonder, Cornelia; Betz, Gabriele

    2010-09-15

    Existing treatments of onychomycosis are not satisfactory. Oral therapies have many side effects and topical formulations are not able to penetrate into the human nail plate and deliver therapeutical concentrations of active agent in situ. The purpose of the present study was to determine the amount of terbinafine, which permeates through the human nail plate, from liquid formulations containing enhancers, namely hydrophobins A-C in the concentration of 0.1% (w/v). The used reference solution contained 10% (w/v) of terbinafine in 60% (v/v) ethanol/water without enhancer. Permeability studies have been performed on cadaver nails using Franz diffusion cells modified to mount nail plates and filled with 60% (v/v) ethanol/water in the acceptor chamber. Terbinafine was quantitatively determined by HPLC. The amount of terbinafine remaining in the nail was extracted by 96% ethanol from pulverized nail material after permeation experiment and presented as percentage of the dry nail weight before the milling test. Permeability coefficient (PC) of terbinafine from reference solution was determined to be 1.52E-10 cm/s. Addition of hydrophobins improved PC in the range of 3E-10 to 2E-9 cm/s. Remaining terbinafine reservoir in the nail from reference solution was 0.83% (n=2). An increase of remaining terbinafine reservoir in the nail was observed in two out of three tested formulations containing hydrophobins compared to the reference. In all cases, known minimum inhibitory concentration of terbinafine for dermatophytes (0.003 microg/ml) has been exceeded in the acceptor chamber of the diffusion cells. All tested proteins (hydrophobins) facilitated terbinafine permeation after 10 days of permeation experiment, however one of them achieved an outstanding enhancement factor of 13.05 compared to the reference. Therefore, hydrophobins can be included in the list of potential enhancers for treatment of onychomycosis. PMID:20620203

  4. Study of the enhancement effect of cyclopentadecanolide on protein permeation through lipid membranes

    NASA Astrophysics Data System (ADS)

    Li, Zhengmao

    Intranasal drug delivery has been a topic of increasing interest for a decade as a convenient and reliable method for the systemic administration of drugs. The low bioavailability of simple formulation of protein drugs, such as insulin, can be greatly improved by using permeation enhancers. We studied the effect of cyclopentadecanolide (CPE-215RTM) as a permeation enhancer in protein release through lipid bilayer membranes. We successfully designed a novel in-vitro membrane permeability model using liposomes and performed a series of transmembrane protein release experiments. These were carried out under a wide range of conditions in the presence of different permeation enhancer combinations. The experimental results showed that CPE-215RTM is an effective membrane permeation enhancer for proteins and a phase transfer agent, for example, cyclodextrins, can further enhance the effect of CPE-215RTM. Besides the release experiments, studies on insulin solution properties (self-diffusion and self-association states), the interaction between insulin and liposome and the interaction between CPE-215RTM and liposomes were carried out. Based on the mechanistic study and release data, we hypothesized that CPE-215RTM can form transient "pores" in the lipid bilayer that dissolve when CPE-215RTM distributes homogeneously within the bilayer and restore the barrier function of the lipid bilayer. We performed several experiments that corroborate our hypothesis. A mathematical model was developed based on our hypothesized release mechanism. A semi-empirical nonlinear equation involving four parameters effectively fits the protein release profiles. The quality of the data fit with this model is good supporting evidence for the validity of our mechanistic model. Finally we used a neural network approach to correlate the different release condition parameters and the four semi-empirical fitting parameters based on our limited data sets. Reasonable neural networks were formed for the

  5. Design, development and permeation studies of nebivolol hydrochloride from novel matrix type transdermal patches

    PubMed Central

    Jatav, Vijay Singh; Saggu, Jitender Singh; Sharma, Ashish Kumar; Sharma, Anil; Jat, Rakesh Kumar

    2013-01-01

    Background: Nebivolol hydrochloride is a third generation β-blocker with highly selective β1-receptor antagonist with antihypertensive properties having plasma half life of 10 h and 12% oral bioavailability. The aim of the present investigation was to form matrix type transdermal patches containing Nebivolol hydrochloride to avoid its extensive hepatic first pass metabolism, lesser side effect and increase bioavailability of drug. Materials and Methods: Matrix type transdermal patches containing Nebivolol hydrochloride were prepared using EudragitRS100, HPMC K100M (2:8) polymers by solvent evaporation technique. Aluminum foil was used as a backing membrane. Polyethylene glycol (PEG) 400 was used as plasticizer and Dimethyl sulfoxide (DMSO) was used as a penetration enhancer. Drug polymer interactions determined by FTIR and standard calibration curve of Nebivolol hydrochloride were determined by using UV estimation. Result: The systems were evaluated physicochemical parameters and drug present in the patches was determined by scanning electron microscopy. All prepared formulations indicated good physical stability. In vitro drug permeation studies of formulations were performed by using Franz diffusion cells using abdomen skin of Wistar albino rat. Result showed best in vitro skin permeation through rat skin as compared to all other formulations prepared with hydrophilic polymer containing permeation enhancer. Conclusions: It was observed that the formulation containing HPMC: EudragitRS100 (8:2) showed ideal higuchi release kinetics. On the basis of in vitro drug release through skin permeation performance, Formulation F1 was found to be better than other formulations and it was selected as the optimized formulation. PMID:24223377

  6. Skin permeating nanogel for the cutaneous co-delivery of two anti-inflammatory drugs

    PubMed Central

    Shah, Punit; Desai, Pinaki; Patel, Apurva; Singh, Mandip

    2011-01-01

    The aim of this study was to develop an effective drug delivery system for the simultaneous topical delivery of two anti-inflammatory drugs, spantide II (SP) and ketoprofen (KP). To achieve this primary goal we have developed a skin permeating nanogel system (SPN) containing surface modified polymeric bilayered nanoparticles along with a gelling agent. Poly-(lactide-co-glycolic acid) and chitosan were used to prepare bilayered nanoparticles (NPS) and the surface was modified with oleic acid (NPSO). Hydroxypropyl methyl cellulose (HPMC) and Carbopol with the desired viscosity were utilized to prepare the nanogels. The nanogel system was further investigated for in vitro skin permeation, drug release and stability studies. Allergic contact dermatitis (ACD) and psoriatic plaque like model were used to assess the effectiveness of SPN. Dispersion of NPSO in HPMC (SPN) produced a stable and uniform dispersion. In vitro permeation studies revealed increase in deposition of SP for the SP-SPN or SP+KP-SPN in the epidermis and dermis by 8.5 and 9.5 folds, respectively than SP-gel. Further, the deposition of KP for KP-SPN or SP+KP-SPN in epidermis and dermis was 9.75 and 11.55 folds higher, respectively than KP-gel. Similarly the amount of KP permeated for KP-SPN or SP+KP-SPN was increased by 9.92 folds than KP-gel. The ear thickness in ACD model and the expression of IL-17 and IL-23; PASI score and TEWL values in psoriatic plaque like model were significantly less (p<0.001) for SPN compared to control gel. Our results suggest that SP+KP-SPN have significant potential for the percutaneous delivery of SP and KP to the deeper skin layers for treatment of various skin inflammatory disorders. PMID:22118820

  7. Skin permeating nanogel for the cutaneous co-delivery of two anti-inflammatory drugs.

    PubMed

    Shah, Punit P; Desai, Pinaki R; Patel, Apurva R; Singh, Mandip S

    2012-02-01

    The aim of this study was to develop an effective drug delivery system for the simultaneous topical delivery of two anti-inflammatory drugs, spantide II (SP) and ketoprofen (KP). To achieve this primary goal, we have developed a skin permeating nanogel system (SPN) containing surface modified polymeric bilayered nanoparticles along with a gelling agent. Poly-(lactide-co-glycolic acid) and chitosan were used to prepare bilayered nanoparticles (NPS) and the surface was modified with oleic acid (NPSO). Hydroxypropyl methyl cellulose (HPMC) and Carbopol with the desired viscosity were utilized to prepare the nanogels. The nanogel system was further investigated for in vitro skin permeation, drug release and stability studies. Allergic contact dermatitis (ACD) and psoriatic plaque like model were used to assess the effectiveness of SPN. Dispersion of NPSO in HPMC (SPN) produced a stable and uniform dispersion. In vitro permeation studies revealed increase in deposition of SP for the SP-SPN or SP+KP-SPN in the epidermis and dermis by 8.5 and 9.5 folds, respectively than SP-gel. Further, the deposition of KP for KP-SPN or SP+KP-SPN in epidermis and dermis was 9.75 and 11.55 folds higher, respectively than KP-gel. Similarly the amount of KP permeated for KP-SPN or SP+KP-SPN was increased by 9.92 folds than KP-gel. The ear thickness in ACD model and the expression of IL-17 and IL-23; PASI score and TEWL values in psoriatic plaque like model were significantly less (p < 0.001) for SPN compared to control gel. Our results suggest that SP+KP-SPN have significant potential for the percutaneous delivery of SP and KP to the deeper skin layers for treatment of various skin inflammatory disorders. PMID:22118820

  8. Sensitive Procedures for Determining the Permeation Resistance of Chlorinated Polyethylene Against Liquid Propellants

    NASA Technical Reports Server (NTRS)

    Waller, Jess M.; Williams, James H.; Fries, Joseph (Technical Monitor)

    1999-01-01

    The permeation resistance of chlorinated polyethylene (CPE) used in totally encapsulating chemical protective suits against the aerospace fuels hydrazine, monomethylhydrazine, and uns-dimethylhydrazine was determined by measuring the breakthrough time (BT) and time-averaged vapor transmission rate (VTR) using procedures consistent with ASTM F 739 and ASTM F 1383. Two exposure scenarios were simulated: a 2 hour (h) fuel vapor exposure, and a liquid fuel "splash" followed by a 2 h vapor exposure. To simulate internal suit pressure during operation, a positive differential pressure of 0.3 in. water (75 Pa) on the collection side of the permeation apparatus was used. Using the available data, a model was developed to estimate propellant concentrations inside an air-line fed, totally encapsulating chemical protective suit. Concentrations were calculated under simulated conditions of fixed vapor transmission rate, variable breathing air flow rate, and variable splash exposure area. Calculations showed that the maximum allowable permeation rates of hydrazine fuels through CPE were of the order of 0.05 to 0.08 ng/sq cm min for encapsulating suits with low breathing air flow rates (of the order of 5 scfm or 140 L min-1). Above these permeation rates, the 10 parts-per-billion (ppb) threshold limit value time-weighted average could be exceeded. To evaluate suit performance at 10 ppb threshold-limiting value/time-weighted average level concentrations, use of a sensitive analytical method such as cation exchange high performance liquid chromatography with amperometric detection was found to be essential. The analytical detection limit determines the lowest measurable VTR, which in turn governed the lowest per meant concentration that could be calculated inside the totally encapsulating chemical protective suit.

  9. 40 CFR 90.127 - Fuel line permeation from nonhandheld engines and equipment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... specifications in SAE J30 as described in 40 CFR 1060.810. (ii) R12 specifications in SAE J30 as described in 40 CFR 1060.810. (iii) Category 1 specifications in SAE J2260 as described in 40 CFR 1060.810. (iv... permeation emission standard of 15 g/m2/day when measured according to the test procedure described in 40...

  10. 40 CFR 90.127 - Fuel line permeation from nonhandheld engines and equipment.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... specifications in SAE J30 as described in 40 CFR 1060.810. (ii) R12 specifications in SAE J30 as described in 40 CFR 1060.810. (iii) Category 1 specifications in SAE J2260 as described in 40 CFR 1060.810. (iv... permeation emission standard of 15 g/m2/day when measured according to the test procedure described in 40...

  11. 40 CFR 90.127 - Fuel line permeation from nonhandheld engines and equipment.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... specifications in SAE J30 as described in 40 CFR 1060.810. (ii) R12 specifications in SAE J30 as described in 40 CFR 1060.810. (iii) Category 1 specifications in SAE J2260 as described in 40 CFR 1060.810. (iv... permeation emission standard of 15 g/m2/day when measured according to the test procedure described in 40...

  12. 40 CFR 90.127 - Fuel line permeation from nonhandheld engines and equipment.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... specifications in SAE J30 as described in 40 CFR 1060.810. (ii) R12 specifications in SAE J30 as described in 40 CFR 1060.810. (iii) Category 1 specifications in SAE J2260 as described in 40 CFR 1060.810. (iv... permeation emission standard of 15 g/m2/day when measured according to the test procedure described in 40...

  13. Solvent effects in permeation assessed in vivo by skin surface biopsy

    PubMed Central

    Rosado, Catarina; Rodrigues, Luis Monteiro

    2003-01-01

    Background Transdermal drug delivery has become an important means of drug administration. It presents numerous advantages but it is still limited by the small number of drugs with a suitable profile. The use of solvents that affect the skin barrier function is one of the classic strategies of penetration enhancement. Some of these solvents have well characterised actions on the stratum corneum, but the majority are still selected using empirical criteria. The objective of this work was to conduct a systematic study on the ability to affect skin permeation of solvents commonly used in transdermal formulations. An innovative methodology in this area was employed, consisting of the combination of skin surface biopsy with colorimetry. Methods The study compared in vivo differences in the permeation of a hydrophilic (methylene blue) and a lipophilic (Sudan III) dye, after treatment of the skin with different vehicles. Consecutive skin surface biopsies of each site were taken and the cumulative amounts of the dyes in the stripped stratum corneum were measured by reflectance colourimetry. Results Results indicate that the amount of methylene blue present in the stratum corneum varied significantly with different skin pre-treatments. Some solvents provided a 1.5 fold penetration enhancement but others decreased by almost half the permeation of the dye. The permeation of Sudan III was less significantly affected by solvent pre-treatment. Conclusions This study has only superficially explored the potential of the combination of skin surface biopsy and colourimetry, but the encouraging results obtained confirm that the methodology can be extended to the study of more complex formulations. PMID:14680512

  14. Effects of hypothyroidism on vascular /sup 125/I-albumin permeation and blood flow in rats

    SciTech Connect

    Tilton, R.G.; Pugliese, G.; Chang, K.; Speedy, A.; Province, M.A.; Kilo, C.; Williamson, J.R.

    1989-05-01

    Effects of hypothyroidism on vascular 125I-albumin permeation and on blood flow were assessed in multiple tissues of male Sprague-Dawley rats rendered hypothyroid by dietary supplementation with 0.5% (wt/wt) 2-thiouracil or by thyroidectomy. In both thiouracil-treated and thyroidectomized rats, body weights, kidney weight, arterial blood pressure, and pulse rate were decreased significantly v age-matched controls. After 10 to 12 weeks of thiouracil treatment, 125I-albumin permeation was increased significantly in the kidney, aorta, eye (anterior uvea, choroid, retina), skin, and new granulation tissue, remained unchanged in brain, sciatic nerve, and heart, and was decreased in forelimb skeletal muscle. A similar pattern was observed in thyroidectomized rats, except that increases in 125I-albumin permeation for all tissues were smaller than those observed in thiouracil-treated rats, and 125I-albumin permeation in retina did not differ from controls. In both thiouracil-treated and thyroidectomized rats, changes in blood flow (assessed with 15-microns, 85Sr-labeled microspheres) relative to the decrease in arterial blood pressure were indicative of a decrease in regional vascular resistance except in the choroid and in the kidney, in which vascular resistance was increased significantly. Glomerular filtration rate was decreased, but filtration fraction and urinary excretion of albumin remained unchanged by thiouracil treatment and thyroidectomy. These results indicate that vascular hemodynamics and endothelial cell barrier functional integrity are modulated in many different tissues by the thyroid. In view of the correspondence of hypothyroid- and diabetes-induced vascular permeability changes, these results raise the possibility that altered thyroid function in diabetes may play a role in the pathogenesis of diabetic vascular disease.

  15. Using Rare Gas Permeation to Probe Methanol Diffusion near the Glass Transition Temperature

    NASA Astrophysics Data System (ADS)

    Matthiesen, Jesper; Smith, R. Scott; Kay, Bruce D.

    2009-12-01

    The permeation of rare-gas atoms through deeply supercooled metastable liquid methanol films is used to probe the diffusivity. The technique allows for measurement of supercooled liquid mobility at temperatures near the glass transition. The temperature dependence of the diffusivity is well described by a Vogel-Fulcher-Tamman equation. These new measurements and the temperature dependent kinetic parameters obtained from their analysis provide clear evidence that methanol is a fragile liquid near the glass transition.

  16. Using rare gas permeation to probe methanol diffusion near the glass transition temperature.

    PubMed

    Matthiesen, Jesper; Smith, R Scott; Kay, Bruce D

    2009-12-11

    The permeation of rare-gas atoms through deeply supercooled metastable liquid methanol films is used to probe the diffusivity. The technique allows for measurement of supercooled liquid mobility at temperatures near the glass transition. The temperature dependence of the diffusivity is well described by a Vogel-Fulcher-Tamman equation. These new measurements and the temperature dependent kinetic parameters obtained from their analysis provide clear evidence that methanol is a fragile liquid near the glass transition. PMID:20366212

  17. Final report for Allied-Signal Aerospace Company, Kansas City Division on protective glove permeation analysis

    SciTech Connect

    Swearengen, P.M.; Johnson, J.S.; Priante, S.J.

    1990-06-22

    We conducted 25 separate glove fabric permeation studies during this project. The permeations were carried out in the small (1 inch) glass ASTM cell. One other permeation study was carded out with a large (two inch) modified ASTM cell for comparison with the small cell results. We also compared the LLNL procedure from both large and small cells with the standard ASTM test procedure which uses a liquid solution on the breakthrough side of the fabric (the liquid is then sampled on a periodic basis). In all comparisons we observed a close-correlation in breakthrough times between the two procedures and the two cell sizes. In the course of this study, we tested ten different glove materials. These included neoprene (original ASTM round-robin sheet stock, 16 mil thickness), Edmont Sol-Vex (nitrile), Pioneer nitrile, Pioneer Pylox (polyvinyl chloride), North Viton (trademark for fluoroelastomers), North SilverShield (Norfoil, trademark for a flexible metallized laminate), Safety 4 4H (patented plastic laminate), and QRP PolyTuff (polyurethane) 20G-2000 (5 mil), 23G-2300 (1.5 mil), and 25G-2500 (1.5 mil). Three of the glove materials, Viton and Silver Shield (North), and 4H (Safety 4), did not allow any permeation measurable by our system to either 1,2-dichloroethane or 3% diphenylmercury (in 1,2-dichloroethane) for a period greater than six hours. A fourth material, QRP Poly Tuff 2OG-2000, did not allow any measurable penetration of Asilamine (an aromatic diamine) for a time pedod of greater than 4 hours. Breakthrough times and curves were obtained for all other tested materials. Eleven different chemicals were used to challenge the glove materials. These included acetone, Asilamine, 1,2-dichloroethane, dichloromethane, isopropyl alcohol, a mixture of 3% diphenylmercury in 1,2-dichloroethane (w/w), phenol, and lso Verre Stripper, 4,4`-methylenedianil (MDA), 1,3-phenylenediamine (MPDA), and Shell Epon (R) curing agent Z.

  18. Membrane permeation process for dehydration of organic liquid mixtures using sulfonated ion-exchange polyalkene membranes

    DOEpatents

    Cabasso, Israel; Korngold, Emmanuel

    1988-01-01

    A membrane permeation process for dehydrating a mixture of organic liquids, such as alcohols or close boiling, heat sensitive mixtures. The process comprises causing a component of the mixture to selectively sorb into one side of sulfonated ion-exchange polyalkene (e.g., polyethylene) membranes and selectively diffuse or flow therethrough, and then desorbing the component into a gas or liquid phase on the other side of the membranes.

  19. Transferrin Receptor 1 Facilitates Poliovirus Permeation of Mouse Brain Capillary Endothelial Cells.

    PubMed

    Mizutani, Taketoshi; Ishizaka, Aya; Nihei, Coh-Ichi

    2016-02-01

    As a possible route for invasion of the CNS, circulating poliovirus (PV) in the blood is believed to traverse the blood-brain barrier (BBB), resulting in paralytic poliomyelitis. However, the underlying mechanism is poorly understood. In this study, we demonstrated that mouse transferrin receptor 1 (mTfR1) is responsible for PV attachment to the cell surface, allowing invasion into the CNS via the BBB. PV interacts with the apical domain of mTfR1 on mouse brain capillary endothelial cells (MBEC4) in a dose-dependent manner via its capsid protein (VP1). We found that F-G, G-H, and H-I loops in VP1 are important for this binding. However, C-D, D-E, and E-F loops in VP1-fused Venus proteins efficiently penetrate MBEC4 cells. These results imply that the VP1 functional domain responsible for cell attachment is different from that involved in viral permeation of the brain capillary endothelium. We observed that co-treatment of MBEC4 cells with excess PV particles but not dextran resulted in blockage of transferrin transport into cells. Using the Transwell in vitro BBB model, transferrin co-treatment inhibited permeation of PV into MBEC4 cells and delayed further viral permeation via mTfR1 knockdown. With mTfR1 as a positive mediator of PV-host cell attachment and PV permeation of MBEC4 cells, our results indicate a novel role of TfR1 as a cellular receptor for human PV receptor/CD155-independent PV invasion of the CNS. PMID:26637351

  20. Permeation of a metalworking fluid through a latex glove under field use conditions.

    PubMed

    Xu, Wenhai; Que Hee, Shane S

    2010-01-01

    Whole glove testing for a metalworking fluid (MWF) in the field was performed for the first time. Green latex gloves used in a machine shop were exposed for 20 min to MWF. The permeated amount (1.0 +/- 0.5 microg/cm(2)) was higher than the threshold (0.25 microg/cm(2)) for the ASTM F739-99a closed-loop normalized breakthrough time. PMID:19784533

  1. A comparative analysis of glove permeation resistance to paint stripping formulations.

    PubMed

    Stull, Jeffrey O; Thomas, Richard W; James, Lawrence E

    2002-01-01

    Although there is a wide variety of work gloves available to users of commercial paint stripping products, there are no published studies examining which type of gloves provide the best protection. To address this need, a multiphase study was undertaken to evaluate how several types of gloves resist multichemical-based paint stripping formulations. Due to the wide range of commercial paint stripping formulations available, seven categories of surrogate paint stripper formulations were created to evaluate glove performance initially. Twenty different glove types were identified for initial evaluation. Degradation resistance screening was carried out for each glove style and paint stripping formulation. Screening results were used to identify those glove styles least affected by the surrogate paint strippers. Those gloves were then evaluated for their resistance to permeation using continuous contact testing based on ASTM Test Method F 739. Glove styles showing extensive permeation with early breakthrough were then evaluated to see how they performed with only intermittent contact with the surrogate paint strippers using a modified form of ASTM Test Method F 1383. These results were used to select glove styles to be tested using commercially available paint stripping products. Gloves made of plastic laminate and butyl rubber were the most effective against the majority of paint strippers. More glove styles resisted permeation by N-methylpyrrolidone and dibasic ester-based paint strippers than conventional solvent products such as methylene chloride, methanol, isopropanol, acetone, and toluene. The study also found that decreased contact time caused relatively little change in permeation resistance and that the surrogate paint stripper data did not always accurately predict resistance to the commercial paint stripper formulations. PMID:11843429

  2. Electric-field-controlled water and ion permeation of a hydrophobic nanopore.

    PubMed

    Dzubiella, J; Hansen, J-P

    2005-06-15

    The permeation of hydrophobic, cylindrical nanopores by water molecules and ions is investigated under equilibrium and out-of-equilibrium conditions by extensive molecular-dynamics simulations. Neglecting the chemical structure of the confining pore surface, we focus on the effects of pore radius and electric field on permeation. The simulations confirm the intermittent filling of the pore by water, reported earlier under equilibrium conditions for pore radii larger than a critical radius R(c). Below this radius, water can still permeate the pore under the action of a strong electric field generated by an ion concentration imbalance at both ends of the pore embedded in a structureless membrane. The water driven into the channel undergoes considerable electrostriction characterized by a mean density up to twice the bulk density and by a dramatic drop in dielectric permittivity which can be traced back to a considerable distortion of the hydrogen-bond network inside the pore. The free-energy barrier to ion permeation is estimated by a variant of umbrella sampling for Na(+), K(+), Ca(2+), and Cl(-) ions, and correlates well with known solvation free energies in bulk water. Starting from an initial imbalance in ion concentration, equilibrium is gradually restored by successive ion passages through the water-filled pore. At each passage the electric field across the pore drops, reducing the initial electrostriction, until the pore, of radius less than R(c), closes to water and hence to ion transport, thus providing a possible mechanism for voltage-dependent gating of hydrophobic pores. PMID:16008472

  3. Synthesis of Conjugated Chitosan and its Effect on Drug Permeation from Transdermal Patches

    PubMed Central

    Satheeshababu, B. K.; Shivakumar, K. L.

    2013-01-01

    The aim of this study was to synthesis the conjugated chitosan by covalent attachment of thiol moieties to the cationic polymer, mediated by a carbodiimide to improve permeation properties of chitosan. Thioglycolic acid was covalently attached to chitosan by the formation of amide bonds between the primary amino groups of the polymer and the carboxylic acid groups of thioglycolic acid. Hence, these polymers are called as thiomers or thiolated polymers. Conjugation of chitosan was confirmed by Fourier transform-infrared and differential scanning calorimetric analysis. Matrix type transdermal patches of carvedilol were prepared using the different proportions of chitosan and chitosan-thioglycolic acid conjugates (2:0, 1.7:0.3, 1.4:0.6, 1:1, 0.6:1.4 and 0.3:1.7) by solvent casting technique. Prepared matrix type patches were evaluated for their physicochemical characterization followed by in vitro evaluation. Selected formulations were subjected for their ex vivo studies on Wistar albino rat skin and human cadaver skin using the modified Franz diffusion cell. As the proportion of conjugated chitosan increased, the transdermal patches showed increased drug permeation. The mechanism of drug release was found to be nonFickian profiles. The present study concludes that the transdermal patches of carvedilol using conjugated chitosan with different proportions of chitosan were successfully developed to provide improved drug permeation. The transdermal patches can be a good approach to improve drug bioavailability by bypassing the extensive hepatic first-pass metabolism of the drug. PMID:24019564

  4. Optical coherence tomography in quantifying the permeation of human plasma lipoproteins in vascular tissues

    NASA Astrophysics Data System (ADS)

    Ghosn, M. G.; Mashiatulla, M.; Tuchin, V. V.; Morrisett, J. D.; Larin, K. V.

    2012-03-01

    Atherosclerosis is the most common underlying cause of vascular disease, occurring in multiple arterial beds including the carotid, coronary, and femoral arteries. Atherosclerosis is an inflammatory process occurring in arterial tissue, involving the subintimal accumulation of low-density lipoproteins (LDL). Little is known about the rates at which these accumulations occur. Measurements of the permeability rate of LDL, and other lipoproteins such as high-density lipoprotein (HDL) and very low-density lipoprotein (VLDL), could help gain a better understanding of the mechanisms involved in the development of atherosclerotic lesions. The permeation of VLDL, LDL, HDL, and glucose was monitored and quantified in normal and diseased human carotid endarterectomy tissues at 20°C and 37°C using optical coherence tomography (OCT). The rates for LDL permeation through normal tissue at 20°C was (3.16 +/- 0.37) × 10-5 cm/sec and at 37°C was (4.77 +/- 0.48) × 10-5 cm/sec, significantly greater (p<0.05) than the rates for diseased tissue at these temperatures ((1.97 +/- 0.34) × 10-5 cm/sec and (2.01 +/- 0.23) × 10-5 cm/sec, respectively). The observed results support previous suggestions of an enhanced transport mechanism specific to LDL. This study effectively uses optical coherence tomography to measure the rates of permeation of vascular tissue by the range of naturally occurring lipoproteins.

  5. An X-ray diffraction analysis of crystallised whey and whey-permeate powders.

    PubMed

    Nijdam, Justin; Ibach, Alexander; Eichhorn, Klaus; Kind, Matthias

    2007-11-26

    Amorphous whey, whey-permeate and lactose powders have been crystallised at various air temperatures and humidities, and these crystallised powders have been examined using X-ray diffraction. The most stable lactose crystal under normal storage conditions, alpha-lactose monohydrate, forms preferentially in whey and whey-permeate powders at 50 degrees C, provided sufficient moisture is available, whereas anhydrous beta-lactose and mixed anhydrous lactose crystals, which are unstable under normal storage conditions, form preferentially at 90 degrees C. Thus, faster crystallisation at higher temperatures is offset by the formation of lactose-crystal forms that are less stable under normal storage conditions. Very little alpha-lactose monohydrate crystallised in the pure lactose powders over the range of temperatures and humidities tested, because the crystallisation of alpha- and beta-lactose is considerably more rapid than the mutarotation of beta- to alpha-lactose in the amorphous phase and the hydration of alpha-lactose during crystallisation. Protein and salts hinder the crystallisation process, which provides more time for mutarotation and crystal hydration in the whey and whey-permeate powders. PMID:17719020

  6. In vitro percutaneous permeation and skin accumulation of finasteride using vesicular ethosomal carriers.

    PubMed

    Rao, Yuefeng; Zheng, Feiyue; Zhang, Xingguo; Gao, Jianqing; Liang, Wenquan

    2008-01-01

    In order to develop a novel transdermal drug delivery system that facilitates the skin permeation of finasteride encapsulated in novel lipid-based vesicular carriers (ethosomes)finasteride ethosomes were constructed and the morphological characteristics were studied by transmission electron microscopy. The particle size, zeta potential and the entrapment capacity of ethosome were also determined. In contrast to liposomes ethosomes were of more condensed vesicular structure and they were found to be oppositely charged. Ethosomes were found to be more efficient delivery carriers with high encapsulation capacities. In vitro percutaneous permeation experiments demonstrated that the permeation of finasteride through human cadaver skin was significantly increased when ethosomes were used. The finasteride transdermal fluxes from ethosomes containing formulation (1.34 +/- 0.11 microg/cm(2)/h) were 7.4, 3.2 and 2.6 times higher than that of finasteride from aqueous solution, conventional liposomes and hydroethanolic solution respectively (P < 0.01).Furthermore, ethosomes produced a significant (P < 0.01) finasteride accumulation in the skin, especially in deeper layers, for instance in dermis it reached to 18.2 +/- 1.8 microg/cm(2). In contrast, the accumulation of finasteride in the dermis was only 2.8 +/- 1.3 microg/cm(2) with liposome formulation. The study demonstrated that ethosomes are promising vesicular carriers for enhancing percutaneous absorption of finasteride. PMID:18649143

  7. EFFECT OF MICRONEEDLE TREATMENT ON THE SKIN PERMEATION OF A NANOENCAPSULATED DYE

    PubMed Central

    Gomaa, Yasmine A.; El-Khordagui, Labiba K.; Garland, Martin J.; Donnelly, Ryan F.; McInnes, Fiona; Meidan, Victor M.

    2014-01-01

    Objectives The aim of the study was to investigate the effect of microneedle (MN) treatment on the transdermal delivery of a model drug (rhodamine B, Rh B) encapsulated in polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) focusing on the MN characteristics and application variables. Methods Gantrez® MNs were fabricated using laser-engineered silicone micro-mould templates. PLGA NPs were prepared using a modified emulsion–diffusion–evaporation method and characterized in vitro. Permeation of encapsulated Rh B through MN treated full thickness porcine skin was performed using Franz diffusion cells using appropriate controls. Key findings In vitro skin permeation of the nanoencapsulated Rh B (6.19 ± 0.77 μg/cm2/ h) was significantly higher (P<0.05) compared to the free solution (1.66 ± 0.53 μg/cm2/ h). Mechanistic insights were supportive of preferential and rapid deposition of NPs in the MN-created microconduits, resulting in accelerated dye permeation. Variables such as MN array configuration and application mode were shown to affect transdermal delivery of the nanoencapsulated dye. Conclusions This dual MN/NPs mediated approach offers potential for both the dermal and transdermal delivery of therapeutic agents with poor passive diffusion. PMID:23058046

  8. Influence of anisotropy on the dynamic wetting and permeation of paper coatings.

    PubMed

    Bodurtha, Paul A; Matthews, G Peter; Kettle, John P; Roy, Ian M

    2005-03-01

    A void network model, named Pore-Cor, has been used to study the permeation of an ink solvent into paper coating formulations coated onto a synthetic substrate. The network model generated anisotropic void networks of rectangular cross-sectional pores connected by elliptical cross-sectional throats. These structures had porosities and mercury intrusion properties which closely matched those of the experimental samples. The permeation of hexadecane, used as an analogue for the experimental test oil, was then simulated through these void structures. The simulations were compared to measurements of the permeation of mineral oil into four types of paper coating formulation. The simulations showed that the inertia of the fluid as it enters void features causes a considerable change in wetting over a few milliseconds, a timescale relevant to printing in a modern press. They also showed that in the more anisotropic samples, fast advance wetting occurred through narrow void features. It was found that the match between experimental and simulated wetting could be improved by correcting the simulation for the number of surface throats. The simulations showed a more realistic experimental trend, and much greater preferential flow, than the traditional Lucas-Washburn and effective hydraulic radius approaches. PMID:15694438

  9. Hydrogen permeation in FeCrAl alloys for LWR cladding application

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

    2015-06-01

    FeCrAl, an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In this study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. The total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

  10. Ondansetron HCl Microemulsions for Transdermal Delivery: Formulation and In Vitro Skin Permeation

    PubMed Central

    Malakar, Jadupati; Nayak, Amit Kumar; Basu, Aalok

    2012-01-01

    Ondansetron HCl delivery through oral route suffers due to its low bioavailability due to first-pass metabolism. Therefore, the microemulsion-based transdermal delivery may be a better substitute for it. The pseudoternary phase diagrams were constructed to determine compositions of microemulsions, and ondansetron HCl microemulsions for transdermal delivery were developed using isopropyl myristate or oleic acid as the oil phase, Tween 80 as the surfactant, and isopropyl alcohol as the cosurfactant evaluated for in vitro skin permeation through excised porcine skin. The in vitro skin permeation from these formulated microemulsions was sustained over 24 hours. The microemulsion F-8 (contained 10% of isopropyl myristate as oil phase, 8% of aqueous phase, and 82% of surfactant phase containing Tween 80 and isopropyl alcohol, 3 : 1) showed the highest permeation flux of 0.284 ± 0.003 μg/cm2/hour. All these microemulsions followed the Korsmeyer-Peppas model (R2 = 0.971  to  0.998) with non-Fickian, “anomalous” mechanism over a period of 24 hours. PMID:22779009

  11. Tubular dense perovskite type membranes. Preparation, sealing, and oxygen permeation properties

    SciTech Connect

    Li, S.; Qi, H.; Xu, N.; Shi, J.

    1999-12-01

    Tubular dense perovskite type membranes were prepared by isostatic pressing and plastic extrusion. The resulting tubular La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} perovskite type membrane prepared by plastic extrusion (designated as PE-LSCF) has a lower density and oxygen permeation flux compared with that prepared by isostatic pressing (designated as IP-LSCF). A ceramic binder developed by the research center provided reliable sealing for the tubular dense membrane at high temperature. The oxygen permeation flux increases with increasing temperature, and the value is about 0.13 cm{sup 3}/cm{sup 2} min (STP) at 1,123 K. The activation energy for oxygen permeation is 168 kJ/mol at the temperature range of 1,073--1,173. X-ray diffraction analysis for the membranes over 110 h of operation indicated that SrSO{sub 4}, CoSO{sub 4}, SrO, Co{sub 2}O{sub 3}, and La{sub 2}O{sub 3} were formed on the surfaces of the tubular membrane, especially for the tubular PE-LSCF membrane, because of interaction with trace SO{sub 2} in the air and the helium and segregation of surface elements.

  12. Sealing of pores in sol-gel-derived tritium permeation barrier coating by electrochemical technique

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Hatano, Yuji

    2011-10-01

    An electrolytic deposition technique was applied to seal open pores in sol-gel derived ZrO 2 coating and to improve barrier effects against permeation of hydrogen isotopes. Disk-type specimens of type 430 ferritic stainless steel were first covered by thin ZrO 2 films (50 nm) with a conventional sol-gel technique. Then, pores in the ZrO 2 film was sealed with ZrO 2 or Al 2O 3 by cathodic processes in ethanol solution of Zr or Al nitrate and subsequent heat treatments in air. The permeation rate of hydrogen was measured at 300-600 °C. The sol-gel derived ZrO 2 coatings showed only limited barrier effects; the permeation reduction factor (PRF) was about 6-800. Nevertheless, the treatments by electrolytic deposition technique resulted in considerable improvement in the barrier effects, especially at high temperature region (>500 °C), and the PRF increased to 100-1000.

  13. Effects of some terpenes on the in vitro permeation of LHRH through newborn pig skin.

    PubMed

    Songkro, S; Rades, T; Becket, G

    2009-02-01

    The objective of this work was to investigate the effect of oxygen containing terpenes (carvacrol, menthol and carvone) at 5%w/v in hydroalcoholic mixtures (40% ethanol) on the permeation of LHRH across newborn pig skin in vitro. In addition, the amount of LHRH retained in the skin after 24 h of diffusion was determined. It was found that the passive permeation of LHRH was very limited. Although percutaneous absorption of LHRH improved in the presence of the enhancers, a significant enhancement was observed only with carvacrol, an aromatic terpene. The rank order of enhancement ratio for skin permeation was found to be carvacrol > carvone > menthol. The enhancers also affected the retention of LHRH in the skin. The rank order of enhancement ratio for skin retention was carvone > carvacrol > menthol. The results of the in vitro skin metabolism study of LHRH using fresh newborn pig skin showed that the degradation products were detected and the amount of the degraded LHRH increased with increasing duration of incubation time. PMID:19320284

  14. Hydrogen permeation in FeCrAl alloys for LWR cladding application

    DOE PAGESBeta

    Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

    2015-03-19

    FeCrAl is an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In our study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. Also, the total tritium inventory insidemore » the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.« less

  15. A study on the preparation and gas permeation of porous alumina supports

    SciTech Connect

    Ting-Chia Huang; Huey-Ing Chen

    1995-06-01

    The preparation and gas permeation of porous alumina supports were studied. The influence of the amount of PVA on the properties of the alumina slips, microstructure of the supports, and gas permeation were investigated. The experimental results show that the addition of PVA in the preparation process is useful for controlling the porosity of the supports without significantly changing other microstructural properties. Permeation measurements of H{sub 2}, He, Ch{sub 4}, N{sub 2}, O{sub 2}, and CO{sub 2} showed that gas transport through various supports under low transmembrane pressures (100-220 kPa) at room temperature (26.5{degrees}C) was in the transition region, which combined the Knudsen diffusion and Poiseuille flow. The average radii of active pores for the supports, calculated from the gas permeability method, were compared with those measured by mercury porosimetry. The porosity-tortuosity factors and the tortuosity factors of the supports were also estimated and are discussed.

  16. Hydrogen permeation in FeCrAl alloys for LWR cladding application

    SciTech Connect

    Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

    2015-03-19

    FeCrAl is an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In our study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. Also, the total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

  17. Evaluation of glove material resistance to ethylene glycol dimethyl ether permeation

    SciTech Connect

    Menke, R.; Chelton, C.F.

    1988-08-01

    Some glycol ethers have been reported to cause adverse reproductive effects in exposed male and female workers, and skin absorption has been determined to be an important route of entry of this class of chemicals. Because ethylene glycol dimethyl ether (EGDME) is a possible component of lithium-based primary battery electrolyte systems, a study was undertaken to determine the resistance of various commercially available gloves to permeation of this liquid. The gloves were tested by the ASTM Method F-739-81, and butyl rubber was found to be the most effective barrier to permeation. Further studies determined that the butyl gloves could be reused if they were reconditioned overnight in a vacuum oven at 50 degrees C. When a mixture of ethylene glycol dimethyl ether (30% v/v) and propylene carbonate (70% v/v) was tested, the results indicated that the propylene carbonate retards the permeation of the glycol ether by a factor of 10. This is believed to be caused by the propylene carbonate coating the surface of the butyl membrane to reduce the sorption of EGDME.

  18. Vapor permeation-stepwise injection simultaneous determination of methanol and ethanol in biodiesel with voltammetric detection.

    PubMed

    Shishov, Andrey; Penkova, Anastasia; Zabrodin, Andrey; Nikolaev, Konstantin; Dmitrenko, Maria; Ermakov, Sergey; Bulatov, Andrey

    2016-02-01

    A novel vapor permeation-stepwise injection (VP-SWI) method for the determination of methanol and ethanol in biodiesel samples is discussed. In the current study, stepwise injection analysis was successfully combined with voltammetric detection and vapor permeation. This method is based on the separation of methanol and ethanol from a sample using a vapor permeation module (VPM) with a selective polymer membrane based on poly(phenylene isophtalamide) (PA) containing high amounts of a residual solvent. After the evaporation into the headspace of the VPM, methanol and ethanol were transported, by gas bubbling, through a PA membrane to a mixing chamber equipped with a voltammetric detector. Ethanol was selectively detected at +0.19 V, and both compounds were detected at +1.20 V. Current subtractions (using a correction factor) were used for the selective determination of methanol. A linear range between 0.05 and 0.5% (m/m) was established for each analyte. The limits of detection were estimated at 0.02% (m/m) for ethanol and methanol. The sample throughput was 5 samples h(-1). The method was successfully applied to the analysis of biodiesel samples. PMID:26653499

  19. Involvement of Carboxylesterase in Hydrolysis of Propranolol Prodrug during Permeation across Rat Skin

    PubMed Central

    Imai, Teruko; Takase, Yuko; Iwase, Harunobu; Hashimoto, Mitsuru

    2013-01-01

    The use of a prodrug, a conjugate of an active drug with a lipophilic substituent, is a good way of increasing the cutaneous absorption of a drug. However, the activity of dermal hydrolases has rarely been investigated in humans, or experimental animals. In the present study, we focused on the identification of rat dermal esterases and the hydrolysis of a prodrug during permeation across rat skin. We found that carboxylesterase (CES), especially the rat CES1 isozyme, Hydrolase A, is expressed in rat skin and that the hydrolysis of p-nitrophenyl acyl derivatives and caproyl-propranolol (PL) was 20-fold lower in the 9000g supernatant fraction of skin homogenate than in liver microsomes. A permeation study of caproyl-PL was performed in rat full-thickness and stripped skin using a flow-through diffusion cell. Caproyl-PL was easily partitioned into the stratum corneum and retained, not only in the stratum corneum, but also in viable epidermis and dermis. Caproyl-PL could barely be detected in the receptor fluid after application to either full-thickness or stripped skin. PL, derived from caproyl-PL, was, however, detected in receptor fluid after extensive hydrolysis of caproyl-PL in viable skin. Permeation of PL was markedly decreased under CES inhibition, indicating that the net flux of caproyl-PL is dependent on its conversion rate to PL. PMID:24300511

  20. Structural Determinants of Water Permeation through the Sodium-Galactose Transporter vSGLT

    PubMed Central

    Adelman, Joshua L.; Sheng, Ying; Choe, Seungho; Abramson, Jeff; Wright, Ernest M.; Rosenberg, John M.; Grabe, Michael

    2014-01-01

    Sodium-glucose transporters (SGLTs) facilitate the movement of water across the cell membrane, playing a central role in cellular homeostasis. Here, we present a detailed analysis of the mechanism of water permeation through the inward-facing state of vSGLT based on nearly 10 μs of molecular dynamics simulations. These simulations reveal the transient formation of a continuous water channel through the transporter that permits water to permeate the protein. Trajectories in which spontaneous release of galactose is observed, as well as those in which galactose remains in the binding site, show that the permeation rate, although modulated by substrate occupancy, is not tightly coupled to substrate release. Using a, to our knowledge, novel channel-detection algorithm, we identify the key residues that control water flow through the transporter and show that solvent gating is regulated by side-chain motions in a small number of residues on the extracellular face. A sequence alignment reveals the presence of two insertion sites in mammalian SGLTs that flank these outer-gate residues. We hypothesize that the absence of these sites in vSGLT may account for the high water permeability values for vSGLT determined via simulation compared to the lower experimental estimates for mammalian SGLT1. PMID:24655503

  1. Rapid human skin permeation and topical anaesthetic activity of a new amethocaine microemulsion.

    PubMed

    Escribano, E; Obach, M; Arévalo, M I; Calpena, A C; Domenech, J; Queralt, J

    2005-01-01

    We developed a fast-acting, topical, 4% (w/w) amethocaine microemulsion and tested its in vitro permeation in isolated human skin. Comparison with a commercial amethocaine gel (Ametop((R)) ) was performed using Franz diffusion cells. Permeability coefficient (k(p)), flux (J) and percentage permeation after 10 h of microemulsion application were, in all cases, 1.5 times higher than those of the gel. The values obtained for the P(1) parameter [1], 1.06.10(-2) cm (microemulsion) and 0.724.10(-2) cm (gel) indicate that the microemulsion excipients favour amethocaine deposition in the skin, increasing the permeability coefficient, amount of drug retained in the skin, and the flux achieved. Analgesic activity was also examined in rats made hyperalgesic or allodynic after carrageenan-induced inflammation. The rats were distributed into four groups (n = 5-9 per group), each group receiving topically either amethocaine microemulsion, amethocaine gel (Ametop), amethocaine subcutaneous infiltration or nothing (controls). In edematous paws, anti-hyperalgesic activity appeared at 4.2 and 13.8 min after application of amethocaine microemulsion and gel, respectively. These effects are lower than after 0.5% w/w amethocaine infiltration. Amethocaine microemulsion was the only topical formulation with an anti-allodynic effect, although this effect was less than with amethocaine infiltration. These results suggest that microemulsion could be a valuable formula for improving amethocaine permeation and thus bringing rapid pain relief. PMID:16179817

  2. Novel PdAgCu ternary alloy: Hydrogen permeation and surface properties

    NASA Astrophysics Data System (ADS)

    Tarditi, Ana M.; Braun, Fernando; Cornaglia, Laura M.

    2011-05-01

    Dense PdAgCu ternary alloy composite membranes were synthesized by the sequential electroless plating of Pd, Ag and Cu on top of both disk and tubular porous stainless steel substrates. X-ray diffraction and scanning electron microscopy were employed to study the structure and morphology of the tested samples. The hydrogen permeation performance of these membranes was investigated over a 350-450 °C temperature range and a trans-membrane pressure up to 100 kPa. After annealing at 500 °C in hydrogen stream followed by permeation experiments, the alloy layer presented a FCC crystalline phase with a bulk concentration of 68% Pd, 7% Ag and 25% Cu as revealed by EDS. The PdAgCu tubular membrane was found to be stable during more than 300 h on hydrogen stream. The permeabilities of the PdAgCu ternary alloy samples were higher than the permeabilities of the PdCu alloy membranes with a FCC phase. The co-segregation of silver and copper to the membrane surface was observed after hydrogen permeation experiments at high temperature as determined by XPS.

  3. Influence of membrane-solvent-solute interactions on solute permeation in model membranes.

    PubMed

    Dias, Monica; Hadgraft, Jonathan; Lane, Majella E

    2007-05-01

    The interaction of the components of topical formulations with the skin is an important consideration for effective drug delivery and efficacy. The relative importance of solubility parameters and other solvent properties on membrane diffusion processes has not been fully elucidated in the literature. In this paper, the effect of different vehicles on the permeation of caffeine, salicylic acid and benzoic acid through silicone membranes was evaluated. Polydimethylsiloxane membranes were used as model membranes for comparing the release characteristics of saturated solutions of model permeants because of their homogeneity and uniformity. Log P (octanol-water partition coefficient) and solubility parameter values were calculated for the compounds under study. In vitro diffusion studies indicated that the permeation profiles of all solutes showed a similar pattern. The permeation rates of benzoic acid and salicylic acid through silicone membrane from saturated solutions were higher than those for caffeine reflecting the more lipophilic nature of these compounds in comparison with caffeine. Solvent uptake studies confirmed that the vehicles that were highly sorbed by the membrane altered its properties and hence the flux. Vehicles that were not sorbed by the membrane showed similar steady-state fluxes for the model drugs. This suggests that the diffusion process is mainly influenced by the interactions between the vehicles and the membrane. Solubility parameter alone cannot explain the interactions between the membrane and the vehicles in all cases. Rather, it is likely that membrane flux reflects a combination of different solvent and solute characteristics, such as size, shape and charge distribution. PMID:17204382

  4. Skin permeation profile and anti-inflammatory effect of anemonin extracted from weilingxian.

    PubMed

    Ning, Yuming; Rao, Yuefeng; Yu, Zhenwei; Liang, Wenquan; Li, Fanzhu

    2016-03-01

    The aim of this study was to evaluate the skin permeability of anemonin, which was extracted from the Chinese herb weilingxian, and its potency of relieving the inflammation caused by rheumatoid arthritis (RA). To optimize the formulation, the solubility of anemonin in water and selected concentration of ethanol-water vehicles was determined. The effect of ethanol on the permeation of anemonin through human skin was then studied. Additionally, the influences of hydroxypropyl methylcellulose E50 (HPMC) and Carbomer 934 in different concentrations on the permeation of drug were investigated. Finally, the anti-inflammatory effect of the optimized formulation was assessed by murine model of xylene-induced ear edema. The results showed that the solubility and transdermal permeation of anemonin in ethanol-water vehicles linearly depended on the ethanol concentration. The combination of 30% ethanol and 3% Azone had a synergistic enhancement effect and was therefore selected for gel preparation. The 0.14% anemonin gel prepared with 1% HPMC exhibited the highest transdermal flux. The xylene-induced ear edema inhibitory rate of the optimized formulation was 48.85%. The results indicated that transdermal administration of anemonin is a potential modality for combating inflammation caused by RA. PMID:27183707

  5. Evaluation of glove material resistance to ethylene glycol dimethyl ether permeation.

    PubMed

    Menke, R; Chelton, C F

    1988-08-01

    Some glycol ethers have been reported to cause adverse reproductive effects in exposed male and female workers, and skin absorption has been determined to be an important route of entry of this class of chemicals. Because ethylene glycol dimethyl ether (EGDME) is a possible component of lithium-based primary battery electrolyte systems, a study was undertaken to determine the resistance of various commercially available gloves to permeation of this liquid. The gloves were tested by the ASTM Method F-739-81, and butyl rubber was found to be the most effective barrier to permeation. Further studies determined that the butyl gloves could be reused if they were reconditioned overnight in a vacuum oven at 50 degrees C. When a mixture of ethylene glycol dimethyl ether (30% v/v) and propylene carbonate (70% v/v) was tested, the results indicated that the propylene carbonate retards the permeation of the glycol ether by a factor of 10. This is believed to be caused by the propylene carbonate coating the surface of the butyl membrane to reduce the sorption of EGDME. PMID:3177216

  6. Permeation of substituted silanes and siloxanes through selected gloves and protective clothing.

    PubMed

    Nelson, G O; Priante, S J; Strong, M; Anderson, D; Fallon-Carine, J

    2000-01-01

    Testing of the permeation resistance of eight glove and suit barriers against commercially available substituted silanes and siloxanes was performed using the ASTM F739-96 standard test method. In addition to barrier performance to the pure organosilanes, the permeation rates of the hydrolysis product (usually ethanol or methanol) were investigated. The silanes and siloxanes used as the challenge agents were N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane; 3-chloropropyltrimethoxysilane; ethyltriacetoxysilane; 3-glycidoxypropyltrimethoxysilane; 1,1,1,3,3,3-hexamethyldisilazane; hexamethyldisiloxane; 3-methacryloxypropyltrimethoxysilane; methyltriacetoxysilane (50%)/ethyltriacetoxysilane (50%); methyltrimethoxysilane; methyltris(methylethylketoxime)silane; phenyltrimethoxysilane; polydimethyl siloxanes (PS 340); octamethylcyclotetrasiloxane (D4); tetraethoxysilane; tetramethoxysilane; 1,1,3,3-tetramethyl disiloxane; triethoxysilane; trimethoxysilane; vinyltrimethoxysilane; and vinyltris(methylethylketoxime)silane. Protective gloves tested were nitrile rubber, neoprene rubber, butyl rubber, 4H laminate, and polyvinyl chloride. Garments tested included Tyvek/Saranex 23P, CPF 2, and Responder, all made by Kappler Safety Group. In all cases the protective suit materials lasted 8 hours or more. The only glove that lasted 8 hours against all chemicals was the 4H laminate. The polyvinyl chloride glove lasted 10 min to 8 hours or more depending on the chemical. The nitrile, neoprene, and butyl rubber gloves lasted from 53 min to 8 hours or more depending on the chemical. The alcohol permeation was similar to the organosilicon compounds. The suit materials and the butyl glove all lasted more than 8 hours for both methanol and ethanol. PMID:11071423

  7. Application of a continuous intrinsic dissolution-permeation system for relative bioavailability estimation of polymorphic drugs.

    PubMed

    Zhou, Yuefang; Chu, Weijing; Lei, Ming; Li, Jin; Du, Wei; Zhao, Chunshun

    2014-10-01

    A new continuous dissolution-permeation system, consisting of an intrinsic dissolution apparatus and an Ussing chamber, was developed for screening and identification of high-bioavailability polymorphisms at pre-formulation stages. Three different solid forms of two model drugs (agomelatine and carbamazepine) were used to confirm the system's predictive ability. Ranks for cumulative permeation of the three solids were: Form III>Form I>Form II for agomelatine, and Form III>Form I>the dihydrate form for carbamazepine. Regression analysis of these parameters and published pharmacokinetics confirmed linear IVIVCs (most correlation coefficients >0.9). To confirm dissolution-absorption relationships, permeability coefficients were calculated. Relatively constant values among various polymorphisms for each drug supported a linear dependency between polymorphism-increased dissolution and polymorphism-enhanced permeation. A combined analysis of intrinsic dissolution rates and permeability coefficients revealed that both drugs are of the BCS II class and have dissolution-limited absorption. In conclusion, our new system was valuable not only for high-bioavailability polymorphism screening, but also for drug classification within the BCS system. PMID:25014368

  8. Microelectrode investigation of oxygen permeation in perfluorinated proton exchange membranes with different equivalent weights

    SciTech Connect

    Buechi, F.N.; Wakizoe, Masanobu; Srinivasan, S.

    1996-03-01

    Oxygen concentrations (C{sub b}) and diffusion coefficients (D) in various proton exchange membranes were measured using chronoamperometry at microelectrodes. These measurements were made under conditions similar to those prevailing in proton-exchange-membrane fuel cells. Knowledge of the D and C{sub b} parameters is essential for the determination of oxygen permeation in the catalytic layers of gas diffusion electrodes, which could be rate limiting in these low-temperature fuel cells. Furthermore, the D and C{sub b} values also provide the permeation rates of oxygen through the bulk of the proton conducting membrane. it was found that the concentration of oxygen increased and the diffusion coefficient decreased with increasing equivalent weight of the membranes. These results were interpreted using a model based on the microstructure of the swollen membranes separated into two phases, one hydrophobic and the other hydrophilic, with distinctly different O{sub 2}-permeation properties. According to this model the relative amounts of the two phases in the membranes, caused by the different water contents, determine the O{sub 2} solubility and diffusion coefficient in the different membrane materials.

  9. Experimental Evaluation of Hybrid Distillation-Vapor Permeation Process for Efficient Ethanol Recovery from Ethanol-Water Mixtures

    EPA Science Inventory

    The energy demand of distillation-based systems for ethanol recovery and dehydration can be significant, particularly for dilute solutions [1]. An alternative separation process integrating vapor stripping with a vapor compression step and a vapor permeation membrane separation ...

  10. Membrane-assisted vapor stripping: energy efficient hybrid distillation-vapor permeation process for alcohol-water separation

    EPA Science Inventory

    BACKGROUND: Energy efficient alternatives to distillation for alcohol recovery from dilute solution are needed to improve biofuel sustainability. A process integrating steam stripping with a vapor compression step and a vapor permeation membrane separation step is proposed. The...

  11. Gas separation process using membranes with permeate sweep to remove CO.sub.2 from gaseous fuel combustion exhaust

    DOEpatents

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

    2012-05-15

    A gas separation process for treating exhaust gases from the combustion of gaseous fuels, and gaseous fuel combustion processes including such gas separation. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

  12. In vitro permeation of carvedilol through porcine skin: effect of vehicles and penetration enhancers.

    PubMed

    Gannu, Ramesh; Vishnu, Y Vamshi; Kishan, V; Rao, Y Madhusudan

    2008-01-01

    This investigation studied the effect of vehicles on the in vitro permeation of carvedilol from saturated solutions across porcine skin and selected appropriate penetration enhancers. Labrasol, Transcutol, polyethylene glycol 400, propylene glycol, ethanol, oleic acid, isopropyl myristate, and phosphate buffered saline (pH 7.4) containing 40% v/v polyethylene glycol 400 as control, were used as vehicles; limonene, carvone, camphor, menthol, Transcutol, and Labrasol at 5% w/v concentrations were used as penetration enhancers. Skin permeation studies were conducted in Franz diffusion cells using excised porcine ear skin. Solubility was highest (369.13 mg/mL) in Transcutol, whereas isopropyl myristate showed the lowest solubility (0.79 mg/mL) among all the vehicles. The flux of carvedilol from Transcutol, Labrasol, polyethylene glycol 400, ethanol, and oleic acid was 10.5, 8.6, 4.2, 2.9, and 1.5 times higher, respectively, than that observed with control. The flux obtained using Transcutol was significantly higher (P < 0.05) than the flux obtained using the other vehicles. However, the flux values of carvedilol using isopropyl myristate (P < 0.01) and propylene glycol (P < 0.05) were significantly lower than that of the control. Solutions containing 5% w/v camphor showed maximum permeation (232.54 microg) in 24 h with a flux of 3.19 microg/cm2/h, which was significantly different (P < 0.05) than the flux obtained using other permeation enhancers. The control sample showed lowest permeation (30.50 microg), with a flux of 0.33 microg/cm2/h. The flux of carvedilol from the solutions containing 5% w/v camphor, limonene, Transcutol, carvone, Labrasol, and menthol were 9.7, 7.6, 7.6, 6.3, 4.7, and 2.3 times higher, respectively, than that observed using the control. The present study suggests that Transcutol, Labrasol, and polyethylene glycol 400 may be used as potential vehicles and camphor, limonene, and Transcutol at a 5% w/v level as penetration enhancers. PMID:19174954

  13. The effect of formulation vehicles on the in vitro percutaneous permeation of ibuprofen

    PubMed Central

    2011-01-01

    Background The transdermal application of substances represents an elegant approach to overcome side effects related to injections or oral treatment. Due to benefits like a constant plasma level, no pain during application and a simple therapeutic regime, the optimization of formulations for transdermal drug delivery has gained interest in the last decades. Ibuprofen is a non-steroidal anti-inflammatory compound which is nowadays often used transdermally. The objective of this work was to conduct a study on the effect of different 5% ibuprofen containing formulations (Ibutop® cream, Ibutop® gel, and ibuprofen solution in phosphate buffered saline) on the in vitro-percutaneous permeation of ibuprofen through skin to emphasise the importance of the formulation on percutaneous permeation and skin reservoir. Methods The permeation experiments were conducted in Franz-type diffusion cells according to OECD guideline 428 with 2 mg/cm2 ibuprofen formulation on each skin sample. Ibuprofen was analysed in the receptor fluid and extracted skin samples by UV-VIS high-performance liquid-chromatography at 238 nm. The plot of the cumulative amount of ibuprofen permeated versus time was employed to calculate the apparent permeability coefficient, the maximum flux and the lagtime, all of which were statistically analysed by One-way ANOVA. Results Although ibuprofen permeation out of the gel increases rapidly within the first four hours, the cream produced the highest ibuprofen delivery through the skin within 28 hours, followed by the solution and the gel. A significant shorter lagtime was found after gel treatment compared with the cream and the solution. After 28 hours 59% of the applied ibuprofen was found in the receptor fluid of the cream treated samples, 26% in the solution treated samples and 21% in the samples treated with the gel. Fourfold higher ibuprofen reservoirs were found in the solution and gel treated skin samples compared to the cream treated skin samples

  14. Drug release and permeation studies of nanosuspensions based on solidified reverse micellar solutions (SRMS).

    PubMed

    Friedrich, I; Reichl, S; Müller-Goymann, C C

    2005-11-23

    Solidified reverse micellar solutions (SRMS), i.e. mixtures of lecithin and triglycerides, offer high solubilisation capacities for different types of drugs in contrast to simple triglyceride systems [Friedrich, I., Müller-Goymann, C.C., 2003. Characterisation of SRMS and production development of SRMS-based nanosuspensions. Eur. J. Pharm. Biopharm. 56, 111-119]. Nanosuspensions based on SRMS were prepared by homogenisation close to the melting point of the SRMS matrix. In a first step the SRMS matrices of 1:1 (w/w) ratios of lecithin and triglycerides were loaded with 17beta-estradiol-hemihydrate (EST), hydrocortisone (HC) or pilocarpine base (PB), respectively, and subsequently ground in liquid nitrogen to minimise drug diffusion later on. The powder was then dispersed in a polysorbate 80 solution using high pressure homogenisation. The drug loading capacities of the nanosuspensions were very high in the case of poorly water-soluble EST (99% of total 0.1%, w/w, EST) and HC (97% of total 0.5%, w/w, HC) but not sufficient with the more hydrophilic PB (37-40% of total 1.0%, w/w, PB). These findings suggest SRMS-based nanosuspensions to be promising aqueous drug carrier systems for poorly soluble drugs like EST and HC. Furthermore, in vitro drug permeation from the different drug-loaded nanosuspensions was performed across human cornea construct (HCC) as an organotypical cell culture model. PB permeation did not differ from the nanosuspension and an aqueous solution whereas the permeation coefficients of HC-loaded nanosuspensions were reduced in comparison to aqueous and oily solutions of HC. However, the permeated amount was higher from the nanosuspensions due to a much lower HC concentration in the solution than that in the nanosuspension (solution 0.02%, w/w, versus nanosuspension 0.5%, w/w). The high drug load of the nanoparticles provides prolonged HC release. Permeated amounts of EST were reduced in comparison to HC and only detectable with an ELISA technique

  15. Transdermal delivery of diclofenac using water-in-oil microemulsion: formulation and mechanistic approach of drug skin permeation.

    PubMed

    Thakkar, Priyanka J; Madan, Parshotam; Lin, Senshang

    2014-05-01

    The objective of the present investigation was to enhance skin permeation of diclofenac using water-in-oil microemulsion and to elucidate its skin permeation mechanism. The w/o microemulsion formulations were selected based on constructed pseudoternary phase diagrams depending on water solubilization capacity and thermodynamic stability. These formulations were also subjected to physical characterization based on droplet size, viscosity, pH and conductivity. Permeation of diclofenac across rat skin using side-by-side permeation cells from selected w/o microemulsion formulations were evaluated and compared with control formulations. The selected w/o microemulsion formulations were thermodynamically stable, and incorporation of diclofenac sodium into microemulsion did not affect the phase behavior of system. All microemulsion formulations had very low viscosity (11-17 cps) and droplet size range of 30-160 nm. Microemulsion formulations exhibited statistically significant increase in diclofenac permeation compared to oily solution, aqueous solution and oil-Smix solution. Higher skin permeation of diclofenac was observed with low Smix concentration and smaller droplet size. Increase in diclofenac loading in aqueous phase decreased the partition of diclofenac. Diclofenac from the oil phase of microemulsion could directly partition into skin, while diclofenac from the aqueous droplets was carried through skin by carrier effect. PMID:23634780

  16. Ketotifen Fumarate and Salbutamol Sulphate Combined Transdermal Patch Formulations: In vitro release and Ex vivo Permeation Studies

    PubMed Central

    Yousuf, M.; Ahmad, M.; Usman, M.; Ali, I.

    2013-01-01

    The present work was performed to develop and evaluate transdermal patches of combined antiasthmatic drugs (salbutamol sulphate and ketotifen fumarate). Polyvinyl alcohol membrane was used as backing membrane and eudragit RL-100 was used as matrix material to suspend the drugs in the continuous thickness of the patch. Methanol was solvent and propylene glycol was used as plasticizer. Tween 20, isopropyl myristate, eucalyptus oil, castor oil and span-20 were used as permeability enhancers. Thickness, weight variation and drug uniformity were investigated. The patch formulations were also subjected to drug release in dissolution media and permeation through rabbit skin. Effects of different enhancers were evaluated on release and permeation of drugs. F3 formulations having isopropyl myristate as permeation enhancer, showed maximum amounts of drugs release (88.11% of salbutamol sulphate and 88.33% of ketotifen fumarate) at the end of 24 h dissolution study. F3 also showed maximum permeation of both drugs (4.235 mg salbutamol sulphate and 1.057 mg ketotifen fumarate) after 24 h permeation study through rabbit skin mounted in Franz cell. The patches having no enhancer in the formulation also showed some drug release and permeation due to the presence of plasticizer. The results of the study suggested that new controlled release transdermal formulations of combined antiasthmatic drugs can be suitably developed as an alternate to conventional dosage forms. PMID:24403658

  17. A novel pH-sensitive membrane from chitosan--TEOS IPN; preparation and its drug permeation characteristics.

    PubMed

    Park, S B; You, J O; Park, H Y; Haam, S J; Kim, W S

    2001-02-01

    A novel organic-inorganic composite membrane was prepared, using tetra ethyl ortho silicate (TEOS) as an inorganic material and chitosan as an organic compound. Equilibrium and oscillatory swelling studies were conducted to investigate swelling behaviors of the membrane according to the pH of the swelling medium. Drug permeation experiments were also performed in phosphate buffer solution of the pH of 2.5 and 7.5, respectively. Lidocaine HCl, sodium salicylate and 4-acetamidophenol were selected as model drugs to examine the effect of ionic property of drug on the permeation behavior. The effects of membrane composition and the external pH on the swelling and the drug permeation behavior of IPN membrane could be summarized as follows; chitosan incorporated into TEOS IPN swelled at pH 2.5 while shrunk at pH 7.5. This swelling behavior was completely reversible and the membrane responded rapidly to the change in environmental pH condition. According to swelling behavior, an increase in pH from 2.5 to 7.5 yielded an increase in the rate of drug permeation because of the shrinking of the incorporated chitosan in TEOS IPN, while decrease in pH resulted in low permeation rate. The optimal TEOS-chitosan ratio for maximum pH-sensitivity existed and drug permeation was influenced not only with the external pH but also with the ionic interactions between the drug and membrane. PMID:11205435

  18. Incorporation of whey permeate, a dairy effluent, in ethanol fermentation to provide a zero waste solution for the dairy industry.

    PubMed

    Parashar, Archana; Jin, Yiqiong; Mason, Beth; Chae, Michael; Bressler, David C

    2016-03-01

    This study proposes a novel alternative for utilization of whey permeate, a by-product stream from the dairy industry, in wheat fermentation for ethanol production using Saccharomyces cerevisiae. Whey permeates were hydrolyzed using enzymes to release fermentable sugars. Hydrolyzed whey permeates were integrated into wheat fermentation as a co-substrate or to partially replace process water. Cold starch hydrolysis-based simultaneous saccharification and fermentation was done as per the current industrial protocol for commercial wheat-to-ethanol production. Ethanol production was not affected; ethanol yield efficiency did not change when up to 10% of process water was replaced. Lactic acid bacteria in whey permeate did not negatively affect the co-fermentation or reduce ethanol yield. Whey permeate could be effectively stored for up to 4 wk at 4 °C with little change in lactose and lactic acid content. Considering the global abundance and nutrient value of whey permeate, the proposed strategy could improve economics of the dairy and biofuel sectors, and reduce environmental pollution. Furthermore, our research may be applied to fermentation strategies designed to produce value-added products other than ethanol. PMID:26723112

  19. Hydrogen permeation resistant heat pipe for bi-modal reactors. Final report, October 1, 1994--September 30, 1995

    SciTech Connect

    North, M.T.; Anderson, W.G.

    1995-12-31

    The principal objective of this program was to demonstrate technology that will make a sodium heat pipe tolerant of hydrogen permeation for a bimodal space reactor application. Special focus was placed on techniques which enhance the permeation of hydrogen out of the heat pipe. Specific objectives include: define the detailed requirements for the bimodal reactor application; design and fabricate a prototype heat pipe tolerant of hydrogen permeation; and test the prototype heat pipe and demonstrate that hydrogen which permeates into the heat pipe is removed or reduced to acceptable levels. The results of the program were fully successful. Analyses were performed on two different heat pipe designs and an experimental heat pipe was fabricated and tested. A model of the experimental heat pipe was developed to predict the enhancement in the hydrogen permeation rate out of the heat pipe. A significant improvement in the rate at which hydrogen permeates out of a heat pipe was predicted for the use of the special condenser geometry developed here. Agreement between the model and the experimental results was qualitatively good. Inclusion of the additional effects of fluid flow in the heat pipe are recommended for future work.

  20. Importance of the Direct Contact of Amorphous Solid Particles with the Surface of Monolayers for the Transepithelial Permeation of Curcumin.

    PubMed

    Kimura, Shunsuke; Kasatani, Sachiha; Tanaka, Megumi; Araki, Kaeko; Enomura, Masakazu; Moriyama, Kei; Inoue, Daisuke; Furubayashi, Tomoyuki; Tanaka, Akiko; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-02-01

    The amorphization has been generally known to improve the absorption and permeation of poorly water-soluble drugs through the enhancement of the solubility. The present study focused on the direct contact of amorphous solid particles with the surface of the membrane using curcumin as a model for water-insoluble drugs. Amorphous nanoparticles of curcumin (ANC) were prepared with antisolvent crystallization method using a microreactor. The solubility of curcumin from ANC was two orders of magnitude higher than that of crystalline curcumin (CC). However, the permeation of curcumin from the saturated solution of ANC was negligible. The transepithelial permeation of curcumin from ANC suspension was significantly increased as compared to CC suspension, while the permeation was unlikely correlated with the solubility, and the increase in the permeation was dependent on the total concentration of curcumin in ANC suspension. The absorptive transport of curcumin (from apical to basal, A to B) from ANC suspension was much higher than the secretory transport (from basal to apical, B to A). In vitro transport of curcumin through air-interface monolayers is large from ANC but negligible from CC particles. These findings suggest that the direct contact of ANC with the absorptive membrane can play an important role in the transport of curcumin from ANC suspension. The results of the study suggest that amorphous particles may be directly involved in the transepithlial permeation of curcumin. PMID:26656401

  1. Application of ceramic membranes for microalgal biomass accumulation and recovery of the permeate to be reused in algae cultivation.

    PubMed

    Nędzarek, Arkadiusz; Drost, Arkadiusz; Harasimiuk, Filip; Tórz, Agnieszka; Bonisławska, Małgorzata

    2015-12-01

    The present study was carried out to investigate the possibility of using ceramic membranes for microalgal biomass densification and to evaluate the qualitative composition of the permeate as a source of nitrogen and phosphorus for microalgae cultivated in a closed system. The studies were conducted on the microalga Monoraphidium contortum. The microfiltration process was carried out on a quarter-technical scale using ceramic membranes with 1.4 μm, 300 and 150 kDa cut-offs. Permeate flux and respective hydraulic resistances were calculated. Dissolved inorganic nitrogen and phosphorus fractions were measured in the feed and the permeate. It was noted that the permeate flux in the MF process was decreasing while the values of reversible and irreversible resistances were increasing as the cut-off of the studied membranes was diminishing. An analysis of the hydraulic series resistance showed that using a 300 kDa membrane would be the most beneficial, as it was characterized by a comparatively high permeate flux (Jv=1.68 10(-2)m(3)/m(2)s), a comparatively low susceptibility to irreversible fouling (1.72·10(9) 1/m) and a high biomass retention coefficient (91%). The obtained permeate was characterized by high concentrations of dissolved nitrogen and phosphorus forms, which indicated that it could be reused in the process of microalgal biomass production. PMID:26546921

  2. Ketotifen Fumarate and Salbutamol Sulphate Combined Transdermal Patch Formulations: In vitro release and Ex vivo Permeation Studies.

    PubMed

    Yousuf, M; Ahmad, M; Usman, M; Ali, I

    2013-09-01

    The present work was performed to develop and evaluate transdermal patches of combined antiasthmatic drugs (salbutamol sulphate and ketotifen fumarate). Polyvinyl alcohol membrane was used as backing membrane and eudragit RL-100 was used as matrix material to suspend the drugs in the continuous thickness of the patch. Methanol was solvent and propylene glycol was used as plasticizer. Tween 20, isopropyl myristate, eucalyptus oil, castor oil and span-20 were used as permeability enhancers. Thickness, weight variation and drug uniformity were investigated. The patch formulations were also subjected to drug release in dissolution media and permeation through rabbit skin. Effects of different enhancers were evaluated on release and permeation of drugs. F3 formulations having isopropyl myristate as permeation enhancer, showed maximum amounts of drugs release (88.11% of salbutamol sulphate and 88.33% of ketotifen fumarate) at the end of 24 h dissolution study. F3 also showed maximum permeation of both drugs (4.235 mg salbutamol sulphate and 1.057 mg ketotifen fumarate) after 24 h permeation study through rabbit skin mounted in Franz cell. The patches having no enhancer in the formulation also showed some drug release and permeation due to the presence of plasticizer. The results of the study suggested that new controlled release transdermal formulations of combined antiasthmatic drugs can be suitably developed as an alternate to conventional dosage forms. PMID:24403658

  3. Effect of Permeate Drag Force on the Development of a Biofouling Layer in a Pressure-Driven Membrane Separation System▿

    PubMed Central

    Eshed, L.; Yaron, S.; Dosoretz, C. G.

    2008-01-01

    The effect of permeate flux on the development of a biofouling layer on cross-flow separation membranes was studied by using a bench-scale system consisting of two replicate 100-molecular-weight-cutoff tubular ultrafiltration membrane modules, one that allowed flow of permeate and one that did not (control). The system was inoculated with Pseudomonas putida S-12 tagged with a red fluorescent protein and was operated using a laminar flow regimen under sterile conditions with a constant feed of diluted (1:75) Luria-Bertani medium. Biofilm development was studied by using field emission scanning electron microscopy and confocal scanning laser microscopy and was subsequently quantified by image analysis, as well as by determining live counts and by permeate flux monitoring. Biofilm development was highly enhanced in the presence of permeate flow, which resulted in the buildup of complex three-dimensional structures on the membrane. Bacterial transport toward the membrane by permeate drag was found to be a mechanism by which cross-flow filtration contributes to the buildup of a biofouling layer that was more dominant than transport of nutrients. Cellular viability was found to be not essential for transport and adhesion under cross-flow conditions, since the permeate drag overcame the effect of bacterial motility. PMID:18931284

  4. Transdermal delivery of nicardipine: an approach to in vitro permeation enhancement.

    PubMed

    Aboofazeli, Reza; Zia, Hossein; Needham, Thomas E

    2002-01-01

    Nicardipine hydrochloride (NC-HCl), a calcium channel blocker for the treatment of chronic stable angina and hypertension, seems to be a potential therapeutic transdermal system candidate, mainly due to its low dose, short half-life, and high first-pass metabolism. The objective of the present study was to evaluate its flux and elucidate mechanistic effects of formulation components on transdermal permeation of the drug through the skin. Solubility of NC-HCl in different solvent systems was determined using a validated HPLC method. The solubility of drug in various solvent systems was found to be in decreasing order as propylene glycol (PG)/oleic acid (OA)/dimethyl isosorbide (DMI) (80:10:10 v/v) > PG > PG/OA (90:10 v/v) > polyethylene glycol 300 > ethanol/PG (70:30 w/w) > transcutol > dimethyl isosorbide (DMI) > ethanol > water and buffer 4.7 > 2-propanol. Propylene glycol was then selected as the main vehicle in the development of a transdermal product. As a preliminary step to develop a transdermal delivery system, vehicle effect on the percutaneous absorption of NC-HCl was determined using the excised skin of a hairless guinea pig. Vehicles investigated included pure solvents alone and their selected blends, chosen based on the solubility results. In vitro permeation data were collected at 37 degrees C, using Franz diffusion cells. The skin permeation was then evaluated by measuring the steady state permeation rate (flux) of NC-HCl, lag time, and the permeability constant. The results showed that no individual solvent was capable of promoting NC-HCl penetration. Permeation profiles of the drug through hairless guinea pig skin using saturated solutions of drug were constructed. Among the systems studied, the ternary mixture of PG/OA/DMI and binary mixture of PG/OA showed excellent flux. The flux value of the ternary system was nearly three times higher than the corresponding values obtained for the binary solvent. A similar trend also was observed for the

  5. Design, Synthesis of Novel Lipids as Chemical Permeation Enhancers and Development of Nanoparticle System for Transdermal Drug Delivery

    PubMed Central

    Shah, Punit P.; Etukala, Jagan Reddy; Vemuri, Adithi; Singh, Mandip

    2013-01-01

    In the present study, we designed and developed novel lipids that include (Z)-1-(Octadec-9-en-1-yl)-pyrrolidine (Cy5T), 1, 1-Di-((Z)-octadec-9-en-1-yl)pyrrolidin-1-ium iodide (Cy5), (Z)-1-(Octadec-9-en-1-yl)-piperidine (Cy6T), and 1, 1-Di-((Z)-octadec-9-en-1-yl) piperidin-1-ium iodide (Cy6) to enhance the transdermal permeation of some selected drugs. Firstly, we evaluated the transdermal permeation efficacies of these lipids as chemical permeation enhancers in vehicle formulations for melatonin, ß-estradiol, caffeine, α-MSH, and spantide using franz diffusion cells. Among them Cy5 lipid was determined to be the most efficient by increasing the transdermal permeation of melatonin, ß-estradiol, caffeine, α-MSH, and spantide by 1.5 to 3.26-fold more at the epidermal layer and 1.3 to 2.5-fold more at the dermal layer, in comparison to either NMP or OA. Hence we developed a nanoparticle system (cy5 lipid ethanol drug nanoparticles) to evaluate any further improvement in the drug penetration. Cy5 lipid formed uniformly sized nanoparticles ranging from 150–200 nm depending on the type of drug. Further, Cy5 based nanoparticle system significantly (p<0.05) increased the permeation of all the drugs in comparison to the lipid solution and standard permeation enhancers. There were about 1.54 to 22-fold more of drug retained in the dermis for the Cy5 based nanoparticles compared to OA/NMP standard enhancers and 3.87 to 66.67-fold more than lipid solution. In addition, epifluorescent microscopic analysis in rhodamine-PE permeation studies confirmed the superior permeation enhancement of LEDs (detection of fluorescence up to skin depth of 340 μm) more than lipid solution, which revealed fluorescence up to skin depth of only 260 μm. In summary the present findings demonstrate that i) cationic lipid with 5 membered amine heterocyclic ring has higher permeating efficacy than the 6 membered amine hertocyclic ring. ii) The nanoparticle system prepared with Cy5 showed

  6. Thiolated polycarbophil/glutathione: defining its potential as a permeation enhancer for oral drug administration in comparison to sodium caprate.

    PubMed

    Perera, Glen; Barthelmes, Jan; Vetter, Anja; Krieg, Christof; Uhlschmied, Cindy; Bonn, Günther K; Bernkop-Schnürch, Andreas

    2011-08-01

    Thiolated polyacrylates were shown to be permeation enhancers with notable potential. The aim of this study was to evaluate the permeation enhancing properties of a thiolated polycarbophil/glutathione (PCP-Cys/GSH) system for oral drug application in comparison to a well-established permeation enhancer, namely sodium caprate. In vitro permeation studies were conducted in Ussing-type chambers with sodium fluoresceine (NaFlu) and fluoresceine isothiocyanate labeled dextran (molecular mass 4 kDa; FD4) as model compounds. Bioavailability studies were carried out in Sprague Dawley rats with various formulations. Moreover, cytotoxic effects of both permeation enhancers were compared. Permeation enhancement ratios of 1% sodium caprate were found to be 3.0 (FD4) and 2.3 (NaFlu), whereas 1% PCP-Cys/0.5% GSH displayed enhancement ratios of 2.4 and 2.2. Both excipients performed at a similar level in vivo. Sodium caprate solutions increased oral bioavailability 2.2-fold (FD4) and 2.3-fold (NaFlu), while PCP-Cys hydrogels led to a 3.2-fold and 2.2-fold enhancement. Cell viability experiments revealed a significantly higher tolerance of Caco-2 cells towards 0.5% PCP-Cys (81% survival) compared to 0.5% sodium caprate (5%). As PCP-Cys is not absorbed from mucosal membranes due to its comparatively high molecular mass, systemic side-effects can be excluded. In conclusion, both systems displayed a similar potency for permeation enhancement of hydrophilic compounds. However, PCP-Cys seems to be less harmful to cultured cells. PMID:21554106

  7. Permeation of 70% isopropyl alcohol through surgical gloves: comparison of the standard methods ASTM F739 and EN 374.

    PubMed

    Mäkelä, Erja A; Vainiotalo, Sinikka; Peltonen, Kimmo

    2003-06-01

    Standard test methods ASTM F739 and EN 374 were compared by assessing the permeation of 70% isopropyl alcohol (2-propanol) through seven brands of surgical gloves. The two standards differ in the flow rates of the collection medium and in the chemical permeation rate at which the breakthrough time (BTT) is detected, the EN detection level being 10 times higher than the permeation rate used by ASTM. In a departure from the EN standard method, a 4 h testing time was used instead of 8 h. All of the tested gloves were from the same manufacturer and were made from either natural rubber (NR) (six brands) or chloroprene rubber (CR) (one brand). Two of the NR glove brands were double layered. For the thin NR gloves (0.22, 0.28 and 0.27 mm) the permeation rates were higher throughout the tests with a flow rate of 474 ml/min (EN) of the collection medium (nitrogen) compared with the permeation rates obtained with a flow rate of 52 ml/min (ASTM). These resulted in BTTs of 4.6, 6.5 and 7.6 min (EN) and 4.8, 6.5 and 9.1 min (ASTM), respectively. No statistical difference could be observed between the BTT values obtained with the two standard methods for any of the thin gloves. Thus, although the ASTM standard has a lower criterion for the detection of permeation, it does not necessarily produce shorter BTTs. For the better barriers the methods yielded more equivalent permeation rate curves and thus the EN BTTs were longer than the ASTM BTTs: the EN results were 21, 80, 122 and >240 min compared with the ASTM results of 12, 32, 38 and 103 min for glove thicknesses of 0.37 (NR), 0.22 + 0.22 (double layered NR), 0.31 + 0.29 (double layered NR) and 0.19 mm (CR), respectively. PMID:12765871

  8. Enhanced permeation of fentanyl from supersaturated solutions in a model membrane.

    PubMed

    Santos, P; Watkinson, A C; Hadgraft, J; Lane, M E

    2011-04-01

    The aim of the present study was to investigate the permeation of fentanyl from supersaturated formulations when applied to silicone membrane. Silicone was chosen in order to separate the effects of supersaturation from other possible influences of volatile formulation components on biological membranes. Supersaturated formulations containing either propylene glycol/water (PG/H(2)O) or propylene glycol/ethanol (PG/Et) were prepared containing varying degrees of saturation (DS) of fentanyl. Permeation of finite and infinite doses of the PG/H(2)O formulations, and finite doses of the PG/Et formulations was investigated using Franz-type diffusion cells. For the PG/H(2)O formulations a good correlation between the flux and the DS of the formulation up to 5 DS for infinite dose studies (r(2)=0.99), and up to 7 DS for finite dose studies (r(2)=0.98), was evident. Similarly, for the PG/Et formulations there is a good correlation between the mean flux and the theoretical DS of the formulation (r(2)=0.95). Except for the 2 DS formulations, no significant differences were seen in the mean flux between PG/H(2)O and PG/Et finite dose studies. The larger fluxes observed for infinite doses of the PG/H(2)O formulations versus finite doses reflect changes in the effective area of diffusion over the time of the experiment for the latter set of experiments. The permeation enhancement observed for PG/Et formulations confirms that enhanced drug thermodynamic activity was induced by ethanol evaporation. PMID:21256946

  9. Permeation measurement of gestodene for some biodegradable materials using Franz diffusion cells.

    PubMed

    Liu, Danhua; Zhang, Chong; Zhang, Xiaowei; Zhen, Zhu; Wang, Ping; Li, Jianxin; Yi, Dongxu; Jin, Ying; Yang, Dan

    2015-09-01

    Biodegradable poly(d,l-lactide) (PDLLA), Poly(trimethylene carbonate) (PTMC), polycaprolactone (PCL), poly(caprolactone-co-d,l-lactide) (PCDLLA) and poly(trimethylene carbonate-co-caprolactone) (PTCL) are recently used for clinical drug delivery system such as subcutaneous contraceptive implant capsule due to their biodegradable properties that they could possess long-term stable performance in vivo without removal, however their permeation rate is unknown. In the work, biodegradable material membranes were prepared by solvent evaporation using chloroform, and commercial silicone rubber membrane served as a control. Gestodene was used as a model drug. Gestodene has high biologic progestational activity which allows for high contraceptive reliability at very low-dose levels. The permeation rate of gestodene for several biodegradable materials was evaluated. In vitro diffusion studies were done using Franz diffusion cells with a diffusion area of 1.33 cm(2). Phosphate buffer solution (PBS, pH 7.4), 10% methanol solution and distilled water were taken in donor and receiver chambers at temperature of 37 °C respectively. The in vitro experiments were conducted over a period of 24 h during which samples were collected at regular intervals. The withdrawn samples were appropriately diluted and measured on UV-vis spectrophotometer at 247 nm. Conclusion data from our study showed that permeation rate of PCDLLA with CL ratio more than 70% could be more excellent than commercial silicone rubber membrane. They may be suitable as a candidate carrier for gestodene subcutaneous contraceptive implants in contraceptive fields. PMID:27134544

  10. Mechanism of chloride permeation in the cystic fibrosis transmembrane conductance regulator chloride channel.

    PubMed

    Linsdell, Paul

    2006-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) functions as a Cl- channel important in transepithelial salt and water transport. While there is a paucity of direct structural information on CFTR, much has been learned about the molecular determinants of the CFTR Cl- channel pore region and the mechanism of Cl- permeation through the pore from indirect structure-function studies. The first and sixth transmembrane regions of the CFTR protein play major roles in forming the channel pore and determining its functional properties by interacting with permeating Cl- ions. Positively charged amino acid side-chains are involved in attracting negatively charged Cl- ions into the pore region, where they interact briefly with a number of discrete sites on the pore walls. The pore appears able to accommodate more than one Cl- ion at a time, and Cl- ions bound inside the pore are probably sensitive to one another's presence. Repulsive interactions between Cl- ions bound concurrently within the pore may be important in ensuring rapid movement of Cl- ions through the pore. Chloride ion binding sites also interact with larger anions that can occlude the pore and block Cl- permeation, thus inhibiting CFTR function. Other ions besides Cl- are capable of passing through the pore, and specific amino acid residues that may be important in allowing the channel to discriminate between different anions have been identified. This brief review summarizes these mechanistic insights and tries to incorporate them into a simple cartoon model depicting the interactions between the channel and Cl- ions that are important for ion translocation. PMID:16157656

  11. Erbium-yttrium-aluminum-garnet laser irradiation ameliorates skin permeation and follicular delivery of antialopecia drugs.

    PubMed

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Aljuffali, Ibrahim A; Li, Yi-Ching; Fang, Jia-You

    2014-11-01

    Alopecia usually cannot be cured because of the available drug therapy being unsatisfactory. To improve the efficiency of treatment, erbium-yttrium-aluminum-garnet (Er-YAG) laser treatment was conducted to facilitate skin permeation of antialopecia drugs such as minoxidil (MXD), diphencyprone (DPCP), and peptide. In vitro and in vivo percutaneous absorption experiments were carried out by using nude mouse skin and porcine skin as permeation barriers. Fluorescence and confocal microscopies were used to visualize distribution of permeants within the skin. Laser ablation at a depth of 6 and 10 μm enhanced MXD skin accumulation twofold to ninefold depending on the skin barriers selected. DPCP absorption showed less enhancement by laser irradiation as compared with MXD. An ablation depth of 10 μm could increase the peptide flux from zero to 4.99 and 0.33 μg cm(-2) h(-1) for nude mouse skin and porcine skin, respectively. The laser treatment also promoted drug uptake in the hair follicles, with DPCP demonstrating the greatest enhancement (sixfold compared with the control). The imaging of skin examined by microscopies provided evidence of follicular and intercellular delivery assisted by the Er-YAG laser. Besides the ablative effect of removing the stratum corneum, the laser may interact with sebum to break up the barrier function, increasing the skin delivery of antialopecia drugs. The minimally invasive, well-controlled approach of laser-mediated drug permeation offers a potential way to treat alopecia. This study's findings provide the basis for the first report on laser-assisted delivery of antialopecia drugs. PMID:25187109

  12. Effects of water-channel attractions on single-file water permeation through nanochannels

    NASA Astrophysics Data System (ADS)

    Xu, Yousheng; Tian, Xingling; Lv, Mei; Deng, Maolin; He, Bing; Xiu, Peng; Tu, Yusong; Zheng, Youqu

    2016-07-01

    Single-file transportation of water across narrow nanochannels such as carbon nanotubes has attracted much attention in recent years. Such permeation can be greatly affected by the water-channel interactions; despite some progress, this issue has not been fully explored. Herein we use molecular dynamics simulations to investigate the effects of water-channel attractions on occupancy, translational (transportation) and orientational dynamics of water inside narrow single-walled carbon nanotubes (SWNTs). We use SWNTs as the model nanochannels and change the strength of water-nanotube attractions to mimic the changes in the hydrophobicity/polarity of the nanochannel. We investigate the dependence of water occupancy inside SWNTs on the water-channel attraction and identify the corresponding threshold values for drying states, wetting-drying transition states, and stably wetting states. As the strength of water-channel attractions increases, water flow increases rapidly first, and then decreases gradually; the maximal flow occurs in the case where the nanochannel is predominately filled with the 1D water wire but with a small fraction of ‘empty states’, indicating that appropriate empty-filling (drying-wetting) switching can promote water permeation. This maximal flow is unexpected, since in traditional view, the stable and tight hydrogen-bonding network of the water wire is the prerequisite for high permeability of water. The underlying mechanism is discussed from an energetic perspective. In addition, the effect of water-channel attractions on reorientational dynamics of the water wire is studied, and a negative correlation between the flipping frequency of water wire and the water-channel attraction is observed. The underlying mechanism is interpreted in term of the axial total dipole moment of inner water molecules. This work would help to better understand the effects of water-channel attractions on wetting properties of narrow nanochannels, and on single

  13. Seawater ultrafiltration: role of particles on organic rejections and permeate fluxes.

    PubMed

    Massé, Anthony; Thi, Hanh Nguyen; Roelens, Guillaume; Legentilhomme, Patrick; Jaouen, Pascal

    2013-01-01

    The role of natural compounds of seawater and added particles on mechanisms of membrane fouling and organic matter rejection has been investigated. Ultrafiltration (100 kDa) has been conducted in both dead-end (out/in) and tangential (in/out) modes on polysulfone hollow fibre membranes. The permeate fluxes are approximately three times higher for tangential ultrafiltration than for dead-end ultrafiltration without differences between settled and non-settled seawaters (NS-SWs) (51-55 L h(-1) m(-2) for tangential and 17-22 L h(-1) m(-2) for dead-end ultrafiltration). Adding bentonite or kieselguhr from 0.13 to 1.13 g L(-1) of suspended solids to NS-SW does not act significantly on permeate fluxes of dead-end contrary to tangential ultrafiltration. For the latter, an addition of particles induces a slight drop of permeate fluxes. Original particles of reconstituted seawater could increase the cake porosity, whereas bentonite and kieselguhr, compounds smaller than original particles, could participate in the formation of a compact cake. The total organic carbon removal was equal to approximately 80% whatever the mode of ultrafiltration may be and the suspended solid concentration ranged from 0.13 to 1.13 g L(-1). Dissolved organic carbon (DOC) and colloidal organic carbon rejection rates were greater for tangential ultrafiltration (37-49%) compared with dead-end ultrafiltration (30-44%) at different concentrations of added particles. Bentonite or kieselguhr addition induced a slight decrease of DOC removal. In the case of particles addition, the worst DOC rejection is found for bentonite. PMID:24527616

  14. Solute permeation across the apoplastic barrier in the perisperm-endosperm envelope in cucumber seeds.

    PubMed

    Amritphale, Dilip; Ramakrishna, P; Singh, Bharat; Sharma, Santosh K

    2010-05-01

    An apoplastic barrier consisting of callose and lipid layers in the perisperm-endosperm (PE) envelope is known to restrict inward and outward transport of solutes in cucurbit seeds. The present work examines permeability properties of the barrier using cucumber seed as a model system. Osmometrically determined osmotic potential of the apoplastic fluid was used as a basis for osmotic studies aimed at examining solute exclusion from the apoplastic barrier in the PE envelope. The assessment of apoplastic permeability involved measuring the amount of anionic and cationic organic dyes diffused into agarose gel discs through the PE envelope. Ionic/non-ionic solutes including polyethylene glycols having Stokes radii permeation through the apoplastic barrier in the PE envelope as indicated by greater seed thickness/breadth ratios. Permeances of dyes across the PE envelope were in the order: 2,6-dichlorophenolindophenol (DCPIP) > 2,3,5-triphenyltetrazolium chloride (TTC) approximately methyl orange approximately methylene blue > Eosin Y > Janus green approximately crystal violet approximately Evans Blue. Permeation time(0.5) for DCPIP and TTC was 9.71 and 9.96 h, respectively. Dyes having Stokes radii < 0.5 nm showed significant inward as well as outward diffusion across the PE envelope in contrast to restricted diffusion of dyes having Stokes radii > 0.5 nm. Size exclusion limit for apoplastic barrier in cucumber PE envelope was resolved to be about 0.5 nm by dye permeation and around 0.8 nm by osmotic studies. Dye permeances depended primarily on particle size as described by a quadratic polynomial function rather than on charge or log D. PMID:20358224

  15. Necrosis of lung epithelial cells during infection with Mycobacterium tuberculosis is preceded by cell permeation.

    PubMed

    Dobos, K M; Spotts, E A; Quinn, F D; King, C H

    2000-11-01

    Mycobacterium tuberculosis establishes infection, progresses towards disease, and is transmitted from the alveolus of the lung. However, the role of the alveolar epithelium in any of these pathogenic processes of tuberculosis is unclear. In this study, lung epithelial cells (A549) were used as a model in which to examine cytotoxicity during infection with either virulent or avirulent mycobacteria in order to further establish the role of the lung epithelium during tuberculosis. Infection of A549 cells with M. tuberculosis strains Erdman and CDC1551 demonstrated significant cell monolayer clearing, whereas infection with either Mycobacterium bovis BCG or Mycobacterium smegmatis LR222 did not. Clearing of M. tuberculosis-infected A549 cells correlated to necrosis, not apoptosis. Treatment of M. tuberculosis-infected A549 cells with streptomycin, but not cycloheximide, demonstrated a significant reduction in the necrosis of A549 cell monolayers. This mycobacterium-induced A549 necrosis did not correlate to higher levels of intracellular or extracellular growth by the mycobacteria during infection. Staining of infected cells with propidium iodide demonstrated that M. tuberculosis induced increased permeation of A549 cell membranes within 24 h postinfection. Quantitation of lactate dehydrogenase (LDH) release from infected cells further demonstrated that cell permeation was specific to M. tuberculosis infection and correlated to A549 cellular necrosis. Inactivated M. tuberculosis or its subcellular fractions did not result in A549 necrosis or LDH release. These studies demonstrate that lung epithelial cell cytotoxicity is specific to infection by virulent mycobacteria and is caused by cellular necrosis. This necrosis is not a direct correlate of mycobacterial growth or of the expression of host cell factors, but is preceded by permeation of the A549 cell membrane and requires infection with live bacilli. PMID:11035739

  16. A novel in situ permeation system and its utility in cancer tissue ablation.

    PubMed

    Watanabe, Masami

    2015-09-01

    Focal ablation therapy is an emerging treatment modality for localized cancer lesions. It is an attractive strategy for inhibiting tumor progression and preventing morbidity associated with open surgery. As for intratissue drug delivery systems for use in local therapy, the convection-enhanced delivery (CED) of liquid drugs has been utilized, particularly for the treatment of malignant brain tumors. Although the conventional CED system is useful for providing drug/vehicle-based local therapy, there are several reported disadvantages in terms of the ability to control the extent of drug diffusion. We herein developed and validated a novel in situ permeation (ISP)-MW-1 system for achieving intratissue drug diffusion. The ISP system includes a perfusion catheter connected to an injector and aspirator, which enables intratissue perfusion of the solute diluted in the vehicle in the tip-inserted cavity. We subsequently evaluated the utility of the ISP-MW-1 system for in situ permeation in a subcutaneous tumor model in hamsters. Dehydrated ethanol, saline and 50% acetic acid were evaluated as the vehicle, and methylene blue was used as a dissolved substance for evaluating the diffusion of the agent. As a result, almost all of the tumor tissue within the capsule (tumor size: ~3 cm) was permeated with the dehydrated ethanol and 50% acetic acid and partially with the saline. We further demonstrated that ISP treatment with 50% acetic acid completely ablated the subcutaneous tumors in all of the treated hamsters (n=3). Therefore, the ISP-MW-1 system is a promising approach for controlling the intratissue diffusion of therapeutic agents and for providing local ablation therapy for cancer lesions. We believe that this system may be applicable to a broad range of medicinal and industrial fields, such as regenerative medicine, drug delivery systems, biochemistry and material technologies as well as cancer therapy. PMID:26134633

  17. Effect of formulation variables on the percutaneous permeation of ketoprofen from gel formulations.

    PubMed

    El-Kattan, A F; Asbill, C S; Kim, N; Michniak, B B

    2000-01-01

    The objectives of our study were to evaluate the effect of four terpene enhancers, enhancer lipophilicity, and ethanol concentration using hydroxypropyl cellulose (HPC) and two Pluronic F-127 (PF-127) gel formulations on the percutaneous permeation of ketoprofen. All experiments were conducted using hairless mouse skin in vitro. Data recorded over 24 hr was compared with that for control gels (containing no terpene) using Franz diffusion cells. In the three gel formulations, the highest increase in the ketoprofen permeation was observed using limonene followed by nerolidol, fenchone, and thymol. Relationships were established between terpene lipophilicity, enhancement ratios for ketoprofen flux (ERflux), and the cumulative amount of ketoprofen after 24 hr (Q24) from the three gel formulations. However, no correlation was established between terpene lipophilicity and ketoprofen skin content values at 24 hr. Ethanol had a synergistic effect on the enhancing activity of the terpenes. Increasing the concentration of ethanol from 10% to 50% was associated with an increase in the permeation of ketoprofen. For example, use of PF-127 gel control (no terpene was included) containing 10% ethanol resulted in a ketoprofen flux of 19 +/- 2 microg/cm2 h and 481 +/- 131 microg/cm2 for Q24. Furthermore, for PF-127 containing 33% ethanol the flux was 34 +/- 3 microg/cm2 h and Q24 was 1,420 +/- 111 microg/cm2. However, HPC gel control that contained 50% ethanol resulted in a ketoprofen flux of 67 +/- 6 microg/cm2 h and 2,839 +/- 222 microg/cm2 for Q24. PMID:10989915

  18. Permeation of the three aromatic dipeptides through lipid bilayers: Experimental and computational study

    NASA Astrophysics Data System (ADS)

    Lee, Brent L.; Kuczera, Krzysztof; Middaugh, C. Russell; Jas, Gouri S.

    2016-06-01

    The time-resolved parallel artificial membrane permeability assay with fluorescence detection and comprehensive computer simulations are used to study the passive permeation of three aromatic dipeptides - N-acetyl-phenylalanineamide (NAFA), N-acetyltyrosineamide (NAYA), and N-acetyl-tryptophanamide (NATA) through a 1,2-dioleoyl-sn-glycero-3-phospocholine (DOPC) lipid bilayer. Measured permeation times and permeability coefficients show fastest translocation for NAFA, slowest for NAYA, and intermediate for NATA under physiological temperature and pH. Computationally, we perform umbrella sampling simulations to model the structure, dynamics, and interactions of the peptides as a function of z, the distance from lipid bilayer. The calculated profiles of the potential of mean force show two strong effects - preferential binding of each of the three peptides to the lipid interface and large free energy barriers in the membrane center. We use several approaches to calculate the position-dependent translational diffusion coefficients D(z), including one based on numerical solution the Smoluchowski equation. Surprisingly, computed D(z) values change very little with reaction coordinate and are also quite similar for the three peptides studied. In contrast, calculated values of sidechain rotational correlation times τrot(z) show extremely large changes with peptide membrane insertion - values become 100 times larger in the headgroup region and 10 times larger at interface and in membrane center, relative to solution. The peptides' conformational freedom becomes systematically more restricted as they enter the membrane, sampling α and β and C7eq basins in solution, α and C7eq at the interface, and C7eq only in the center. Residual waters of solvation remain around the peptides even in the membrane center. Overall, our study provides an improved microscopic understanding of passive peptide permeation through membranes, especially on the sensitivity of rotational diffusion

  19. Permeation of the three aromatic dipeptides through lipid bilayers: Experimental and computational study.

    PubMed

    Lee, Brent L; Kuczera, Krzysztof; Middaugh, C Russell; Jas, Gouri S

    2016-06-28

    The time-resolved parallel artificial membrane permeability assay with fluorescence detection and comprehensive computer simulations are used to study the passive permeation of three aromatic dipeptides-N-acetyl-phenylalanineamide (NAFA), N-acetyltyrosineamide (NAYA), and N-acetyl-tryptophanamide (NATA) through a 1,2-dioleoyl-sn-glycero-3-phospocholine (DOPC) lipid bilayer. Measured permeation times and permeability coefficients show fastest translocation for NAFA, slowest for NAYA, and intermediate for NATA under physiological temperature and pH. Computationally, we perform umbrella sampling simulations to model the structure, dynamics, and interactions of the peptides as a function of z, the distance from lipid bilayer. The calculated profiles of the potential of mean force show two strong effects-preferential binding of each of the three peptides to the lipid interface and large free energy barriers in the membrane center. We use several approaches to calculate the position-dependent translational diffusion coefficients D(z), including one based on numerical solution the Smoluchowski equation. Surprisingly, computed D(z) values change very little with reaction coordinate and are also quite similar for the three peptides studied. In contrast, calculated values of sidechain rotational correlation times τrot(z) show extremely large changes with peptide membrane insertion-values become 100 times larger in the headgroup region and 10 times larger at interface and in membrane center, relative to solution. The peptides' conformational freedom becomes systematically more restricted as they enter the membrane, sampling α and β and C7eq basins in solution, α and C7eq at the interface, and C7eq only in the center. Residual waters of solvation remain around the peptides even in the membrane center. Overall, our study provides an improved microscopic understanding of passive peptide permeation through membranes, especially on the sensitivity of rotational diffusion to

  20. Permeation measurement of gestodene for some biodegradable materials using Franz diffusion cells

    PubMed Central

    Liu, Danhua; Zhang, Chong; Zhang, Xiaowei; Zhen, Zhu; Wang, Ping; Li, Jianxin; Yi, Dongxu; Jin, Ying; Yang, Dan

    2015-01-01

    Biodegradable poly(d,l-lactide) (PDLLA), Poly(trimethylene carbonate) (PTMC), polycaprolactone (PCL), poly(caprolactone-co-d,l-lactide) (PCDLLA) and poly(trimethylene carbonate-co-caprolactone) (PTCL) are recently used for clinical drug delivery system such as subcutaneous contraceptive implant capsule due to their biodegradable properties that they could possess long-term stable performance in vivo without removal, however their permeation rate is unknown. In the work, biodegradable material membranes were prepared by solvent evaporation using chloroform, and commercial silicone rubber membrane served as a control. Gestodene was used as a model drug. Gestodene has high biologic progestational activity which allows for high contraceptive reliability at very low-dose levels. The permeation rate of gestodene for several biodegradable materials was evaluated. In vitro diffusion studies were done using Franz diffusion cells with a diffusion area of 1.33 cm2. Phosphate buffer solution (PBS, pH 7.4), 10% methanol solution and distilled water were taken in donor and receiver chambers at temperature of 37 °C respectively. The in vitro experiments were conducted over a period of 24 h during which samples were collected at regular intervals. The withdrawn samples were appropriately diluted and measured on UV–vis spectrophotometer at 247 nm. Conclusion data from our study showed that permeation rate of PCDLLA with CL ratio more than 70% could be more excellent than commercial silicone rubber membrane. They may be suitable as a candidate carrier for gestodene subcutaneous contraceptive implants in contraceptive fields. PMID:27134544

  1. A novel in situ permeation system and its utility in cancer tissue ablation

    PubMed Central

    WATANABE, MASAMI

    2015-01-01

    Focal ablation therapy is an emerging treatment modality for localized cancer lesions. It is an attractive strategy for inhibiting tumor progression and preventing morbidity associated with open surgery. As for intratissue drug delivery systems for use in local therapy, the convection-enhanced delivery (CED) of liquid drugs has been utilized, particularly for the treatment of malignant brain tumors. Although the conventional CED system is useful for providing drug/vehicle-based local therapy, there are several reported disadvantages in terms of the ability to control the extent of drug diffusion. We herein developed and validated a novel in situ permeation (ISP)-MW-1 system for achieving intratissue drug diffusion. The ISP system includes a perfusion catheter connected to an injector and aspirator, which enables intratissue perfusion of the solute diluted in the vehicle in the tip-inserted cavity. We subsequently evaluated the utility of the ISP-MW-1 system for in situ permeation in a subcutaneous tumor model in hamsters. Dehydrated ethanol, saline and 50% acetic acid were evaluated as the vehicle, and methylene blue was used as a dissolved substance for evaluating the diffusion of the agent. As a result, almost all of the tumor tissue within the capsule (tumor size: ~3 cm) was permeated with the dehydrated ethanol and 50% acetic acid and partially with the saline. We further demonstrated that ISP treatment with 50% acetic acid completely ablated the subcutaneous tumors in all of the treated hamsters (n=3). Therefore, the ISP-MW-1 system is a promising approach for controlling the intratissue diffusion of therapeutic agents and for providing local ablation therapy for cancer lesions. We believe that this system may be applicable to a broad range of medicinal and industrial fields, such as regenerative medicine, drug delivery systems, biochemistry and material technologies as well as cancer therapy. PMID:26134633

  2. Dual roles of the sixth transmembrane segment of the CFTR chloride channel in gating and permeation.

    PubMed

    Bai, Yonghong; Li, Min; Hwang, Tzyh-Chang

    2010-09-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is the only member of the adenosine triphosphate-binding cassette (ABC) transporter superfamily that functions as a chloride channel. Previous work has suggested that the external side of the sixth transmembrane segment (TM6) plays an important role in governing chloride permeation, but the function of the internal side remains relatively obscure. Here, on a cysless background, we performed cysteine-scanning mutagenesis and modification to screen the entire TM6 with intracellularly applied thiol-specific methanethiosulfonate reagents. Single-channel amplitude was reduced in seven cysteine-substituted mutants, suggesting a role of these residues in maintaining the pore structure for normal ion permeation. The reactivity pattern of differently charged reagents suggests that the cytoplasmic part of TM6 assumes a secondary structure of an alpha helix, and that reactive sites (341, 344, 345, 348, 352, and 353) reside in two neighboring faces of the helix. Although, as expected, modification by negatively charged reagents inhibits anion permeation, interestingly, modification by positively charged reagents of cysteine thiolates on one face (344, 348, and 352) of the helix affects gating. For I344C and M348C, the open time was prolonged and the closed time was shortened after modification, suggesting that depositions of positive charges at these positions stabilize the open state but destabilize the closed state. For R352C, which exhibited reduced single-channel amplitude, modifications by two positively charged reagents with different chemical properties completely restored the single-channel amplitude but had distinct effects on both the open time and the closed time. These results corroborate the idea that a helix rotation of TM6, which has been proposed to be part of the molecular motions during transport cycles in other ABC transporters, is associated with gating of the CFTR pore. PMID:20805575

  3. Dual roles of the sixth transmembrane segment of the CFTR chloride channel in gating and permeation

    PubMed Central

    Bai, Yonghong; Li, Min

    2010-01-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is the only member of the adenosine triphosphate–binding cassette (ABC) transporter superfamily that functions as a chloride channel. Previous work has suggested that the external side of the sixth transmembrane segment (TM6) plays an important role in governing chloride permeation, but the function of the internal side remains relatively obscure. Here, on a cysless background, we performed cysteine-scanning mutagenesis and modification to screen the entire TM6 with intracellularly applied thiol-specific methanethiosulfonate reagents. Single-channel amplitude was reduced in seven cysteine-substituted mutants, suggesting a role of these residues in maintaining the pore structure for normal ion permeation. The reactivity pattern of differently charged reagents suggests that the cytoplasmic part of TM6 assumes a secondary structure of an α helix, and that reactive sites (341, 344, 345, 348, 352, and 353) reside in two neighboring faces of the helix. Although, as expected, modification by negatively charged reagents inhibits anion permeation, interestingly, modification by positively charged reagents of cysteine thiolates on one face (344, 348, and 352) of the helix affects gating. For I344C and M348C, the open time was prolonged and the closed time was shortened after modification, suggesting that depositions of positive charges at these positions stabilize the open state but destabilize the closed state. For R352C, which exhibited reduced single-channel amplitude, modifications by two positively charged reagents with different chemical properties completely restored the single-channel amplitude but had distinct effects on both the open time and the closed time. These results corroborate the idea that a helix rotation of TM6, which has been proposed to be part of the molecular motions during transport cycles in other ABC transporters, is associated with gating of the CFTR pore. PMID:20805575

  4. Transdermal film-loaded finasteride microplates to enhance drug skin permeation: Two-step optimization study.

    PubMed

    Ahmed, Tarek A; El-Say, Khalid M

    2016-06-10

    The goal was to develop an optimized transdermal finasteride (FNS) film loaded with drug microplates (MIC), utilizing two-step optimization, to decrease the dosing schedule and inconsistency in gastrointestinal absorption. First; 3-level factorial design was implemented to prepare optimized FNS-MIC of minimum particle size. Second; Box-Behnken design matrix was used to develop optimized transdermal FNS-MIC film. Interaction among MIC components was studied using physicochemical characterization tools. Film components namely; hydroxypropyl methyl cellulose (X1), dimethyl sulfoxide (X2) and propylene glycol (X3) were optimized for their effects on the film thickness (Y1) and elongation percent (Y2), and for FNS steady state flux (Y3), permeability coefficient (Y4), and diffusion coefficient (Y5) following ex-vivo permeation through the rat skin. Morphological study of the optimized MIC and transdermal film was also investigated. Results revealed that stabilizer concentration and anti-solvent percent were significantly affecting MIC formulation. Optimized FNS-MIC of particle size 0.93μm was successfully prepared in which there was no interaction observed among their components. An enhancement in the aqueous solubility of FNS-MIC by more than 23% was achieved. All the studied variables, most of their interaction and quadratic effects were significantly affecting the studied variables (Y1-Y5). Morphological observation illustrated non-spherical, short rods, flakes like small plates that were homogeneously distributed in the optimized transdermal film. Ex-vivo study showed enhanced FNS permeation from film loaded MIC when compared to that contains pure drug. So, MIC is a successful technique to enhance aqueous solubility and skin permeation of poor water soluble drug especially when loaded into transdermal films. PMID:26993962

  5. Determinants of Anion Permeation in the Second Transmembrane Domain of the Mouse Bestrophin-2 Chloride Channel

    PubMed Central

    Qu, Zhiqiang; Hartzell, Criss

    2004-01-01

    Bestrophins have been proposed to constitute a new family of Cl channels that are activated by cytosolic Ca. We showed previously that mutation of serine-79 to cysteine in mouse bestrophin-2 (mBest2) altered the relative permeability and conductance to SCN. In this paper, we have overexpressed various mutant constructs of mBest2 in HEK-293 cells to explore the contributions to anion selectivity of serine-79 and other amino acids (V78, F80, G83, F84, V86, and T87) located in the putative second transmembrane domain (TMD2). Residues selected for mutagenesis were distributed throughout TMD2, but mutations at all positions changed the selectivity. The effects on selectivity were rather modest. Replacement of residues 78, 79, 80, 83, 84, 86, or 87 with cysteine had similar effects: the permeability of the channel to SCN relative to Cl (PSCN/PCl) was decreased three- to fourfold and the relative SCN conductance (GSCN/GCl) was increased five- to tenfold. Side chains at positions 78 and 80 appeared to be situated close to the permeant anion, because the electrostatic charge at these positions affected permeation in specific ways. The effects of charged sulfhydryl-reactive MTS reagents were the opposite in the V78C and F80C mutants and the effects were partially mimicked by substitution of F80 with charged amino acids. In S79T, switching from Cl to SCN caused slow changes in GSCN/GCl (τ = 16.6 s), suggesting that SCN binding to the channel altered channel gating as well as conductance. The data in this paper and other data support a model in which TMD2 plays an important role in forming the bestrophin pore. We suggest that the major determinant in anion permeation involves partitioning of the permeant anion into an aqueous pore whose structural features are rather flexible. Furthermore, anion permeation and gating may be linked. PMID:15452198

  6. Clean-up of a pesticide-lanolin mixture by gel permeation chromatography.

    PubMed

    López-Mesas, M; Crespi, M; Brach, J; Mullender, J P

    2000-12-01

    In this study, the efficiency of a clean-up method by gel permeation chromatography (GPC) for the separation of pesticides from lanolin is analyzed. The pesticides analyzed belong to two different families, organophosphorous and synthetic pyrethroids. Lanolin, a standard mixture of the pesticides, and a lanolin-pesticides mixture are injected in a GPC column. The recoveries and elution times from the GPC column of lanolin (by a gravimetric method) and pesticides (by gas chromatography-electron capture detector) are determined. From this column, a good separation of the lanolin-pesticides mixture is observed. PMID:11144515

  7. Application of numerical methods for diffusion-based modeling of skin permeation.

    PubMed

    Frasch, H Frederick; Barbero, Ana M

    2013-02-01

    The application of numerical methods for mechanistic, diffusion-based modeling of skin permeation is reviewed. Methods considered here are finite difference, method of lines, finite element, finite volume, random walk, cellular automata, and smoothed particle hydrodynamics. First the methods are briefly explained with rudimentary mathematical underpinnings. Current state of the art numerical models are described, and then a chronological overview of published models is provided. Key findings and insights of reviewed models are highlighted. Model results support a primarily transcellular pathway with anisotropic lipid transport. Future endeavors would benefit from a fundamental analysis of drug/vehicle/skin interactions. PMID:22261307

  8. Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

    PubMed Central

    Khan, Muntazim Munir; Filiz, Volkan; Emmler, Thomas; Abetz, Volker; Koschine, Toenjes; Rätzke, Klaus; Faupel, Franz; Egger, Werner; Ravelli, Luca

    2015-01-01

    High free-volume copolymers were prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN) in which a portion of the 3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI) of PIM-1 was replaced with dibutyl anthracene maleimide (4bIII). An investigation of free volume using positron annihilation lifetime spectroscopy (PALS), and gas permeation measurements was carried out for the thin film composite copolymer membranes and compared to PIM-1. The average free volume hole size and the gas permeance of the copolymer membranes increased with decreasing TTSBI content in the copolymer. PMID:26030881

  9. Fermentation alcohol from upstate New York cheese whey permeate: a technical/economic analysis

    SciTech Connect

    Not Available

    1981-08-01

    The results of a venture analysis study are presented, involving building a freestanding alcohol fermentation plant utilizing whey permeate from the six major cheese producers in upstate New York. Alternative Concepts for Energy, ACE, jointly owned by three New England distributors of gasoline and other fuels, would produce the alcohol for use as a gasoline additive. The distillers dried solubles (DDS) resulting as a by-product would be sold primarily to local mills for blending into feed for the dairy, poultry and pet markets.

  10. Effect of surfactants and pH on naltrexone (NTX) permeation across buccal mucosa

    PubMed Central

    Rai, Vishwas; Tan, Hock S.; Michniak-Kohn, Bozena

    2011-01-01

    The objective of this pre-formulation study was to systematically investigate the effects of two surfactants (Brij 58® and Tween 80®) and change in solution pH on in vitro permeation of naltrexone HCl (NTX-HCl) across tissue engineered human buccal mucosa. For the study, 10 mg/mL solutions of Tween 80® (0.1 and 1 % w/v) and Brij 58® (1 % w/v) were prepared in standard artificial saliva buffer solution (pH 6.8). For studying pH effects, solution pH was adjusted to either 7.5 or 8.2. As controls, three concentrations of NTX-HCl (2.5, 10 and 25 mg/mL) were prepared. Using NTX standard solution (10mg/ml; pH 6.8), the permeation was observed between in vitro human and ex vivo porcine mucosa. It was observed that Brij 58® increased the permeation rates of NTX significantly. The flux of 10mg/ml solution (pH 6.8) increased from 1.9 ± 0.6 (×102) to 13.9 ± 2.2 (×102) μg/cm2/h (approximately 6 fold) in presence of 1% Brij 58®. Increasing pH of NTX-HCl solution was found to increase the drug flux from 1.9 ± 0.6 (×102) (pH 6.8) to 3.0 ± 0.6 (×102) (pH 7.4) and 8.0 ± 3.5 (×102) (pH 8.2) μg/cm2/h respectively. Histological analyses exhibited no tissue damage due to exposure of buccal tissue to Brij 58®. The mean permeability coefficients (Kp) for 2.5, 10 and 25 mg/mL solutions of NTX-HCl (pH 6.8) were 5.0 (×10−2), 1.8 (×10−2) and 3.2 (×10−2) cm/h respectively, consistent with data from published literature sources. Increase of NTX flux observed with 1% Brij 58® solution may be due to the effects of ATP. Increase in flux and the shortening of lag time observed by increasing in solution pH confirmed earlier finding that distribution coefficient (log D) of NTX is significantly affected by small increments in pH value and therefore plays an important role in NTX permeation by allowing faster diffusion across tissue engineered human buccal membranes. PMID:21443939

  11. Generation of O2 From CO2 by Glow Discharge And Permeation

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.

    1993-01-01

    Technique for generating supply of highly pure O2 from CO2 developed. First, atomic oxygen at useful partial pressure generated by glow-discharge dissociation of CO2. Atomic oxygen formed in vicinity of hot silver membrane and permeates through membrane to downstream region, where thermally recombined into O2 and pumped away to storage tank. Pure oxygen stored suitable for human consumption and other uses. Originally developed to convert Martian atmosphere of CO2 to O2 for astronaut consumption. Other potential applications include purification of atmospheres in Space Shuttle and Space Station Freedom. Byproduct CO must be handled by other techniques.

  12. Modeling the temperature dependence of N-methylpyrrolidone permeation through butyl- and natural-rubber gloves.

    PubMed

    Zellers, E T; Sulewski, R

    1993-09-01

    This paper describes the temperature dependence of N-methylpyrrolidone (NMP) permeation through gloves used in microelectronics fabrication facilities. One type of butyl-rubber glove (North B161), two types of natural-rubber gloves (Edmont Puretek and Ansell Pacific White), and a natural rubber/nitrile/neoprene-blend glove (Pioneer Trionic) were tested at four temperatures from 25-50 degrees C using the ASTM F739-85 permeation test method. The butyl-rubber glove showed no breakthrough after four hours of exposure at any temperature. The variations with temperature of measured breakthrough times (BT) and steady-state permeation rates (SSPR) for the other gloves were described well by Arrhenius relationships, with BT values decreasing by factors of 7-10 and SSPR values increasing by factors of 4-6 over the temperature range studied. Extrapolation to 70 and 93 degrees C, the temperatures at which degreasing is often performed, yielded BT values of < 2 min and < 0.5 min, respectively, in all cases. With the exception of the butyl-rubber glove, following an initial exposure at 25 degrees C and air drying overnight, low levels of NMP vapor were detected off-gassing from the inner surfaces of the gloves. Experimental results were then compared to those expected from several permeation models. Estimates of the equilibrium solvent solubility, S, were calculated using a model based on three-dimensional solubility parameters. Estimates of the solvent diffusion coefficient, D, were obtained from correlations with either the solvent kinematic viscosity or the product of the Flory interaction parameter, chi, and the solvent molar volume. Combining these values of D and S in Fickian diffusion equations gave modeled BT estimates that were within 23% of experimental values over the temperature range examined. Modeled SSPR values were within 50% (typically within 25%) of experimental values. Another model based on a generalized Arrhenius relationship also provided useful but

  13. Statistical methods for model discrimination. Applications to gating kinetics and permeation of the acetylcholine receptor channel.

    PubMed Central

    Horn, R

    1987-01-01

    Methods are described for discrimination of models of the gating kinetics and permeation of single ionic channels. Both maximum likelihood and regression procedures are discussed. In simple situations, where models are nested, standard hypothesis tests can be used. More commonly, however, non-nested models are of interest, and several procedures are described for model discrimination in these cases, including Monte Carlo methods, which allow the comparison of models at significance levels of choice. As an illustration, the methods are applied to single-channel data from acetylcholine receptor channels. PMID:2435330

  14. Ciclopirox vs amorolfine: in vitro penetration into and permeation through human healthy nails of commercial nail lacquers.

    PubMed

    Monti, Daniela; Tampucci, Silvia; Chetoni, Patrizia; Burgalassi, Susi; Mailland, Federico

    2014-02-01

    One of the pre-requisite for a successful topical antifungal drug indicated for onychomycosis is its bioavailability into the nail unit for achieving fungal eradication and clinical benefit. The aim of this study was to compare in vitro permeation/penetration through and into human nails of amorolfine (MRF) from a 5% anhydrous commercial formulation (Loceryl®) and ciclopirox (CPX) from the 8% aqueous formulation in hydroxypropyl chitosan (HPCH) technology (Onytec®). The ability of the active ingredient to reach efficacious concentrations to inhibit nail pathogens was also evaluated. The amounts of drug permeated and retained in human healthy nails were determined using a suitably modified diffusion apparatus. HPLC analysis of the samples was performed. The HPCH-based CPX formulation demonstrated an efficient penetration into and permeation through the nail plates. Conversely, Loceryl® produced an amount of MRF permeated through and penetrated into the human toenails significantly lower than CPX. The evaluation of the efficacy index showed a higher potential efficacy of Onytec® with respect to Loceryl® on nail pathogens. The present work not only reinforced the previous results on different experimental substrates, but pointed out the superiority of HPCH-based Onytec® formulation containing CPX with respect to Loceryl® commercial product with MRF, both in terms of higher permeation through and penetration into the human nail, and for the efficacy towards the most common ungual pathogens. PMID:24509963

  15. Alteration of the diffusional barrier property of the nail leads to greater terbinafine drug loading and permeation.

    PubMed

    Nair, Anroop B; Sammeta, Srinivasa M; Kim, Hyun D; Chakraborty, Bireswar; Friden, Phillip M; Murthy, S Narasimha

    2009-06-22

    The diffusional barrier property of biological systems varies with ultrastructural organization of the tissues and/or cells, and often plays an important role in drug delivery. The nail plate is a thick, hard and impermeable membrane which makes topical nail drug delivery challenging. The current study investigated the effect of physical and chemical alteration of the nail on the trans-ungual drug delivery of terbinafine hydrochloride (TH) under both passive and iontophoretic conditions. Physical alterations were carried out by dorsal or ventral nail layer abrasion, while chemical alterations were performed by defatting or keratolysis or ionto-keratolysis of the nails. Terbinafine permeation into and across the nail plate following various nail treatments showed similar trends in both passive and iontophoretic delivery, although the extent of drug delivery varied with treatment. Application of iontophoresis to the abraded nails significantly improved (P<0.05) TH permeation and loading compared to abraded nails without iontophoresis or normal nails with iontophoresis. Drug permeation was not enhanced when the nail plate was defatted. Keratolysis moderately enhanced the permeation but not the drug load. Ionto-keratolysis enhanced TH permeation and drug load significantly (P<0.05) during passive and iontophoretic delivery as compared to untreated nails. Ionto-keratolysis may be more efficient in permeabilization of nail plates than long term exposure to keratolysing agents. PMID:19481686

  16. The Role of Partial Crystallinity on Hydrogen Permeation in Fe–Ni–B–Mo Based Metallic Glass Membranes

    SciTech Connect

    Brinkman, K.; Su, D.; Fox, E.; Korinko, P.; Missimer, D.; Adams, T.

    2011-08-15

    A potentially exciting material for membrane separations are metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen embrittlement as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. This study reports on the investigation of time and temperature dependent crystalline phase formation in conjunction with in situ crystallization/hydrogen permeation experiments at elevated temperatures. At temperatures near 400 C a FeNi crystalline phase appears as 22 vol.% inside the host amorphous matrix and the resulting composite structure remains stable over 3 h at temperature. The hydrogen permeation at 400 C of the partially crystalline material is similar to the fully amorphous material near 5 x 10{sup -9} mol H{sub 2}/m s Pa{sup 1/2}, while ambient temperature electrochemical permeation at 25 C revealed an order of magnitude decrease in the permeation of partially crystalline materials due to differences in the amorphous versus crystalline phase activation energy for hydrogen permeation.

  17. Permeation of sumatriptan succinate across human skin using multiple types of self-dissolving microneedle arrays fabricated from sodium hyaluronate.

    PubMed

    Wu, Dan; Katsumi, Hidemasa; Quan, Ying-Shu; Kamiyama, Fumio; Kusamori, Kosuke; Sakane, Toshiyasu; Yamamoto, Akira

    2016-09-01

    Available formulations of sumatriptan succinate (SS) have low bioavailability or are associated with site reactions. We developed various types of self-dissolving microneedle arrays (MNs) fabricated from sodium hyaluronate as a new delivery system for SS and evaluated their skin permeation and irritation in terms of clinical application. In vitro permeation studies with human skin, physicochemical properties (needle length, thickness and density), and penetration enhancers (glycerin, sodium dodecyl sulfate and lauric acid diethanolamide) were investigated. SS-loaded high-density MNs of 800 µm in length were the optimal formulation and met clinical therapeutic requirements. Penetration enhancers did not significantly affect permeation of SS from MNs. Optical coherence tomography images demonstrated that SS-loaded high-density MNs (800 µm) uniformly created drug permeation pathways for the delivery of SS into the skin. SS-loaded high-density MNs induced moderate primary skin irritations in rats, but the skin recovered within 72 h of removal of the MNs. These findings suggest that high-density MNs of 800 µm in length are an effective and promising formulation for transdermal delivery of SS. To our knowledge, this is the first report of SS permeation across human skin using self-dissolving MNs. PMID:26878569

  18. Determination of permeation parameters of experimental PET films coated with SiOx to ethyl acetate, oxygen and water vapour.

    PubMed

    Adamantiadi, A; Badeka, A; Kontominas, M G

    2001-11-01

    The permeation parameters of conventional PET films, films coated with SiOx and SiOx-coated films laminated to LDPE were determined for ethyl acetate using the permeation cell/gas chromatography method. Permeation to O2 and water vapour was also determined to monitor overall changes in the barrier properties of the experimental films. Coating of the PET film was achieved by a 'directed evaporation' method that increased the yield of the coating process from 30-35 to > 70%. It was shown that the SiOx coating increased the film barrier to ethyl acetate by approximately 20-30 times. Permeation values showed low reproducibility, indicating the need for further development and standardization of the 'directed evaporation' web-coating process. The barrier to oxygen and water vapour increased by 20-25 and 12-14 times respectively after coating. The web-coating speed did not seem to influence the barrier properties of the films. Permeation coefficients, diffusion coefficients and solubility coefficients were calculated for all samples. PMID:11665733

  19. Effect of borneol on the transdermal permeation of drugs with differing lipophilicity and molecular organization of stratum corneum lipids.

    PubMed

    Yi, Qi-Feng; Yan, Jin; Tang, Si-Yuan; Huang, Hui; Kang, Li-Yang

    2016-07-01

    The aim of the present paper was to investigate the promoting activity of borneol on the transdermal permeation of drugs with differing lipophilicity, and probe its alterations in molecular organization of stratum corneum (SC) lipids. The toxicity of borneol was evaluated in epidermal keratinocyte HaCaT and dermal fibroblast CCC-HSF-1 cell cultures and compared to known enhancers, and its irritant profile was also assessed by transepidermal water loss (TEWL) evaluation. The promoting effect of borneol on the transdermal permeation of five model drugs, namely 5-fluorouracil, antipyrine, aspirin, salicylic acid and ibuprofen, which were selected based on their lipophilicity denoted by logp value, were performed using in vitro skin permeation studies. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was employed to monitor the borneol-induced alteration in molecular organization of SC lipids. The enhancer borneol displayed lower cytotoxicity or irritation in comparison to the well-established and standard enhancer Azone. Borneol could effectively promote the transdermal permeation of five model drugs, and its enhancement ratios were found to be parabolic curve with the logp values of drugs, which exhibited the optimum permeation activity for relatively hydrophilic drugs (an estimated logp value of -0.5 ∼0.5). The molecular mechanism studies suggested that borneol could perturb the structure of SC lipid alkyl chains, and extract part of SC lipids, resulting in the alteration in the skin permeability barrier. PMID:26635061

  20. Glove permeation tests using novel microchemical techniques for 2, 4-dichlorophenoxyacetic acid (2,4-D) derivatives.

    PubMed

    Lin, Y W; Hee, S S

    1999-05-01

    The aim was to assess the permeation of different herbicide emulsion concentrate formulations of 2,4-dichlorophenoxyacetic acid (2,4-D) as 60.8 and 83.5% butoxyethyl ester (BEE) and 46.8% dimethyl amine salt (DMAS) through four types of glove materials (lined unsupported nitrile, unlined unsupported butyl, Silver Shield laminate, and Viton). This entailed the development of new microchemical techniques to allow sensitive capillary gas chromatography/mass spectrometry (GC/MS) of the permeated herbicide. The 2,4-D DMAS was esterified to the methyl ester by boron trifluoride-methanol complex with 99.2 +/- 3.7% efficiency using microwave heating to minimize reaction time and to process microsamples. The GC/MS detection limit was 5 ng/ml (ppb) of 2,4-D DMAS in the collection medium. The permeates from the ester formulations were analyzed directly for the ester above the detection limit of 9 ng/ml (ppb) BEE. The permeation investigations utilized the American Society for Testing Materials (ASTM)-type permeation cells with liquid collection media. The results showed that these gloves could provide at least 6 h protection for these formulations. PMID:10227869

  1. A Feasibility Study of Pressure Retarded Osmosis Power Generation System based on Measuring Permeation Volume using Reverse Osmosis Membrane

    NASA Astrophysics Data System (ADS)

    Enomoto, Hiroshi; Fujitsuka, Masashi; Hasegawa, Tomoyasu; Kuwada, Masatoshi; Tanioka, Akihiko; Minagawa, Mie

    Pressure Retarded Osmosis (PRO) power generation system is a hydroelectric power system which utilize permeation flow through a semi-permeable membrane. Permeation flow is generated by potential energy of salinity difference between sea water and fresh water. As membrane cost is expensive, permeation performance of membrane must be higher to realize PRO system. We have investigated Reverse Osmosis (RO) membrane products as semi-permeable membrane and measured permeation volume of a few products. Generation power by membrane area calculated from permeation volume is about 0.62W/m2. But by our improvements (more salt water volume, spacer of fresh water channel with a function of discharging concentrated salinity, extra low pressure type of membrane, washing support layer of membrane when generation power reduces to half), generation power may be 2.43W/m2. Then power system cost is about 4.1 million yen/kW. In addition, if support layer of membrane makes thinner and PRO system is applied to the equipment that pumping power on another purpose is avairable (wastewater treatment plant located at the seaside, thermal and nuclear power plant or sea water desalination plant), generation power may be more. By these improvements PRO system may be able to realize at the cost close to photovoltaic power system.

  2. Mucus permeating carriers: formulation and characterization of highly densely charged nanoparticles.

    PubMed

    Pereira de Sousa, Irene; Steiner, Corinna; Schmutzler, Matthias; Wilcox, Matthew D; Veldhuis, Gert J; Pearson, Jeffrey P; Huck, Christian W; Salvenmoser, Willi; Bernkop-Schnürch, Andreas

    2015-11-01

    The GI mucus layer represents a significant block to drug carriers absorption. Taking an example from nature, virus-mimicking nanoparticles (NPs) with highly densely charged surface were designed with the aim to improve their mucus permeation ability. NPs were formulated by combining chitosan with chondroitin sulfate and were characterized by particle size, ζ-potential and hydrophobicity. The interaction occurring between NPs and diluted porcine intestinal mucus was investigated by a new method. Furthermore, the rotating tube technique was exploited to evaluate the NPs permeation ability in fresh undiluted porcine intestinal mucus. NPs (400-500 nm) presenting a slightly positive (4.02 mV) and slightly negative (-3.55 mV) ζ-potential resulted to be hydrophobic and hydrophilic, respectively. On the one hand the hydrophobic NPs undergo physico-chemical changes when incubated with mucus, namely the size increased and the ζ-potential decreased. On the other hand, the hydrophilic NPs did not significantly change size and net charge during incubation with mucus. Both types of NPs showed a 3-fold higher diffusion ability compared to the reference 50/50 DL-lactide/glycolide copolymer NPs (136 nm, -23 mV, hydrophilic). Based on these results, this work gives valuable information for the further design of mucus-penetrating NPs. PMID:25576256

  3. Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

    DOEpatents

    Simpson, Lin Jay

    2013-12-17

    A thin film stack (100, 200) is provided for use in electronic devices such as photovoltaic devices. The stack (100, 200) may be integrated with a substrate (110) such as a light transmitting/transmissive layer. A electrical conductor layer (120, 220) is formed on a surface of the substrate (110) or device layer such as a transparent conducting (TC) material layer (120,220) with pin holes or defects (224) caused by manufacturing. The stack (100) includes a thin film (130, 230) of metal that acts as a barrier for environmental contaminants (226, 228). The metal thin film (130,230) is deposited on the conductor layer (120, 220) and formed from a self-healing metal such as a metal that forms self-terminating oxides. A permeation plug or block (236) is formed in or adjacent to the thin film (130, 230) of metal at or proximate to the pin holes (224) to block further permeation of contaminants through the pin holes (224).

  4. The binary eutectic of NSAIDS and two-phase liquid system for enhanced membrane permeation.

    PubMed

    Yuan, Xudong; Capomacchia, A C

    2005-01-01

    The eutectic properties of binary mixtures of some nonsteroidal anti-inflammatory drugs (NSAIDs) with ibuprofen were studied using differential scanning calorimetry (DSC) and phase equilibrium diagrams. The melting points of selected NSAIDs were significantly depressed due to binary eutectic formation with ibuprofen. Ketoprofen and ibuprofen were selected to study the effect of eutectic formation on membrane permeation using Franz diffusion cells and snake skin as the model membrane. The presence of aqueous isopropyl alcohol (IPA) was necessary to completely transform the solid drugs into an oily state at ambient temperature. As much as the 99.6% of ibuprofen and the 88.8% of ketoprofen added were found in the oily phase of the two-phase liquid system formed when aqueous IPA was added to the eutectic mixture. Due to the high drug concentration in the oily phase, and maximum thermodynamic activity, the two-phase liquid system showed enhanced membrane permeation rates of ibuprofen (37.5 microg/cm2/hr) and ketoprofen (33.4 microg/cm2/hr) compared to other reference preparations used. PMID:15776808

  5. Molecular Dynamics Simulation Study of Permeation of Molecules through Skin Lipid Bilayer.

    PubMed

    Gupta, Rakesh; Sridhar, D B; Rai, Beena

    2016-09-01

    Stratum Corneum (SC), the outermost layer of skin, is mainly responsible for skin's barrier function. The complex lipid matrix of SC determines these barrier properties. In this study, the lipid matrix is modeled as an equimolar mixture of ceramide (CER), cholesterol (CHOL), and free fatty acid (FFA). The permeation of water, oxygen, ethanol, acetic acid, urea, butanol, benzene, dimethyl sulfoxide (DMSO), toluene, phenol, styrene, and ethylbenzene across this layer is studied using a constrained MD simulations technique. Several long constrained simulations are performed at a skin temperature of 310 K under NPT conditions. The free energy profiles and diffusion coefficients along the bilayer normal have been calculated for each molecule. Permeability coefficients are also calculated and compared with experimental data. The main resistance for the permeation of hydrophilic and hydrophobic permeants has been found to be in the interior of the lipid bilayer and near the lipid-water interface, respectively. The obtained permeability is found to be a few orders of magnitude higher than experimental values for hydrophilic molecules while for hydrophobic molecules more discrepancy was observed. Overall, the qualitative ranking is consistent with the experiments. PMID:27518707

  6. Effect of hydration on the permeation of ketoconazole through human nail plate in vitro.

    PubMed

    Gunt, Hemali B; Kasting, Gerald B

    2007-12-01

    The impact of hydration on the permeation of the antifungal drug, ketoconazole, through excised human nails in vitro was evaluated in diffusion cell studies. Nails treated with [(3)H]ketoconazole solvent-deposited onto the dorsal surface were maintained in incubators at 32 degrees C and exposed sequentially to relative humidities (dorsal side) of 15, 40, 80 and 100% over a period of 40 days. The ventral side was bathed in a pH 7.4 phosphate buffer. Ascending and descending humidity regimens were tested. Increasing the ambient RH from 15 to 100% enhanced permeation of radiolabel associated with [(3)H]ketoconazole by a factor of three. Diffusivities estimated from these data and the associated nail water contents (estimated in a separate study) can be described by a free volume theory. Therefore, formulations or treatments, which increase nail hydration, have potential to improve topical therapy for onychomycosis, if a favorable balance between drug delivery and growth conditions for the dermatophytes can be achieved. PMID:17928205

  7. Two-phase melt systems of ibuprofen for enhanced membrane permeation.

    PubMed

    Kang, Lisheng; Park, M O; Jun, H W

    2004-11-01

    A novel method to convert S- and racemic (RS-) ibuprofen (Ibu) into an oily state at ambient temperature (25 degrees C) was developed. Using menthol and aqueous isopropanol (IPA) as melting point depressing agents, the two-phase melt systems (TMSs) of Ibu consisting of a homogeneous oily phase and a homogeneous aqueous phase were obtained. In TMS with a high S-Ibu: menthol ratio and a low IPA content, the oily phase primarily consisted of Ibu and menthol, whereas the majority of the aqueous phase was IPA and buffer. Using this method, the S-Ibu concentration in the oily phase reached as high as 70% (w/w). The compositional phase diagram was obtained using a titration method to study the relationship between the melting states of the solid components and system composition. S- and RS-Ibu showed different phase diagrams, and the maximum concentration of S-Ibu measured in the oily phase of TMS was much greater than that of RS-Ibu. The permeation study of a series of TMS and non-TMS systems showed that S-Ibu penetrated through shed snake skin faster than RS-Ibu, and the contents of IPA and menthol significantly affected the permeation rates of ibuprofen across shed snake skin, which may be attributed to the higher lipophilicity, and thus, higher solubility of S-Ibu in the skin than RS-Ibu. Such results support the use of S-Ibu TMS for topical formulation development. PMID:15581071

  8. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    PubMed Central

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-01-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient ‘green technique’, gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm−2h−1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry. PMID:25819091

  9. Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels.

    PubMed

    Reyes, J P; Huanosta-Gutiérrez, A; López-Rodríguez, A; Martínez-Torres, A

    2015-01-01

    We studied the effects of mutations of positively charged amino acid residues in the pore of X. tropicalis TMEM16A calcium-activated chloride channels: K613E, K628E, K630E; R646E and R761E. The activation and deactivation kinetics were not affected, and only K613E showed a lower current density. K628E and R761E affect anion selectivity without affecting Na(+) permeation, whereas K613E, R646E and the double mutant K613E + R646E affect anion selectivity and permeability to Na(+). Furthermore, altered blockade by the chloride channel blockers anthracene-9-carboxylic acid (A-9-C), 4, 4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) and T16inh-A01 was observed. These results suggest the existence of 2 binding sites for anions within the pore at electrical distances of 0.3 and 0.5. These sites are also relevant for anion permeation and blockade. PMID:25853341

  10. Calcium Ion Flow Permeates Cells through SOCs to Promote Cathode-Directed Galvanotaxis.

    PubMed

    Guo, Liang; Xu, Chunyan; Li, Dong; Zheng, Xiulan; Tang, Jiebing; Bu, Jingyi; Sun, Hui; Yang, Zhengkai; Sun, Wenjing; Yu, Xiaoguang

    2015-01-01

    Sensing and responding to endogenous electrical fields are important abilities for cells engaged in processes such as embryogenesis, regeneration and wound healing. Many types of cultured cells have been induced to migrate directionally within electrical fields in vitro using a process known as galvanotaxis. The underlying mechanism by which cells sense electrical fields is unknown. In this study, we assembled a polydimethylsiloxane (PDMS) galvanotaxis system and found that mouse fibroblasts and human prostate cancer PC3 cells migrated to the cathode. By comparing the effects of a pulsed direct current, a constant direct current and an anion-exchange membrane on the directed migration of mouse fibroblasts, we found that these cells responded to the ionic flow in the electrical fields. Taken together, the observed effects of the calcium content of the medium, the function of the store-operated calcium channels (SOCs) and the intracellular calcium content on galvanotaxis indicated that calcium ionic flow from the anode to the cathode within the culture medium permeated the cells through SOCs at the drift velocity, promoting migration toward the cathode. The RTK-PI3K pathway was involved in this process, but the ROCK and MAPK pathways were not. PC3 cells and mouse fibroblasts utilized the same mechanism of galvanotaxis. Together, these results indicated that the signaling pathway responsible for cathode-directed cellular galvanotaxis involved calcium ionic flow from the anode to the cathode within the culture medium, which permeated the cells through SOCs, causing cytoskeletal reorganization via PI3K signaling. PMID:26447479

  11. The impact of skin viability on drug metabolism and permeation -- BSA toxicity on primary keratinocytes.

    PubMed

    Haberland, A; Schreiber, S; Maia, C Santos; Rübbelke, M K; Schaller, M; Korting, H C; Kleuser, B; Schimke, I; Schäfer-Korting, M

    2006-04-01

    For testing cutaneous absorption of drugs, ingredients of cosmetics and also for risk assessment of industrial compounds predictable in vitro test protocols are under investigation using excised skin or reconstructed human epidermis. Since the metabolizing enzymes expressed by viable skin can influence the absorption behaviour of substances by changing their structure and thereby their physicochemical characteristics, the metabolic capacity should be considered in the design of the test protocols of compounds susceptible to metabolism. Then data, generated using viable reconstructed epidermis may reflect the in vivo situation. Interestingly, bovine serum albumin (BSA) commonly used in receptor media in permeation studies to facilitate solubility of highly lipophilic substances strongly inhibited the metabolism of topically applied prednicarbate in reconstructed epidermis. Here, we show that 5% BSA is toxic to reconstructed epidermis and keratinocytes which was consistent with the earlier findings. While media toxicity (deficiency media) was at least partly the cause of both apoptotic and necrotic processes in keratinocytes, BSA only slightly increased the rate of necrotic cells. Moreover, caspase inhibitors did not reduce BSA toxicity. Yet, the results show that BSA toxicity on keratinocytes has to be carefully considered if this protein is used in permeation studies with reconstructed epidermis. PMID:16182510

  12. Enhancement of Mycophenolate Mofetil Permeation for Topical Use by Eucalyptol and N-Methyl-2-pyrrolidone.

    PubMed

    Amnuaikit, Thanaporn; Songkram, Chalermkiat; Pinsuwan, Sirirat

    2016-01-01

    Mycophenolate mofetil (MMF) is a prodrug of mycophenolic acid (MPA) which can be metabolized by esterase. MMF has been approved by the United States Food and Drug Administration (USFDA) for treatment of psoriasis patient with skin symptoms. However, it remains unclear whether MMF is efficiently effective to treat skin symptoms developed from psoriasis. The insufficient amount of MMF penetrating through the skin results in the treatment failure due to the difficulty in MMF penetration through the stratum corneum. Skin permeation enhancers such as eucalyptol (EUL) and N-methyl-2-pyrrolidone (NMP) potentially aid in increasing skin penetration. This study aimed to investigate the effects of a concentration ratio (% w/v) between two enhancers (EUL and NMP). The results showed that EUL enhanced MMF permeation with an enhancement ratio (ER) of 3.44 while NMP was not able to promote the penetration of MMF. Interestingly, the synergistic effect of the two enhancers was observed with a suitable ratio given that the ER was 8.21. EUL and NMP are promising enhancers for the development of MMF based skin product. PMID:27069715

  13. Tritium permeation barrier-aluminized coating prepared by Al-plating and subsequent oxidation process

    NASA Astrophysics Data System (ADS)

    Guikai, Zhang; Ju, Li; Chang'an, Chen; Sanping, Dou; Guoping, Ling

    2011-10-01

    Aluminum rich coatings forming Al 2O 3 on surface are widely applied as tritium permeation barrier (TPB) on structural materials in fusion reactor. In this work, we proposed a new three-step method for preparing such aluminum rich coating on HR-2 steel: ambient temperature melts salt electroplating followed by heat treating and artificial oxidation at 700 °C. Al deposition from AlCl 3/EMIC was performed with a deposition rate of 15 μm/h. After heat treated for 2 h, the aluminized coating appeared homogeneous, with thickness of 11-13 μm and free of visible porosity, and exhibited a three-layer structure. After oxidized in 10 -2 Pa O 2 for 80 h, the finally fabricated coating showed a double-layered structure consisting of an outer γ-A1 2O 3 layer with thickness of 0.1 μm and inner (Fe,Cr,Mn,Ni)Al/(Fe,Cr,Mn,Ni) 3Al layer of 32 μm thickness, without any visible defects. The deuterium permeation rate through the coated HR-2 steel was reduced by 2-3 orders of magnitude at 600-727 °C.

  14. A crossflow filtration system for constant permeate flux membrane fouling characterization.

    PubMed

    Miller, Daniel J; Paul, Donald R; Freeman, Benny D

    2013-03-01

    Membrane fouling is often characterized using a crossflow filtration apparatus. Typically, the transmembrane pressure (TMP) difference is fixed, and the flux is allowed to decline as the membrane fouls and the resistance to mass transfer increases. However, as flux varies, so too does the rate at which foulants are brought to the membrane surface, so the observed fouling behavior is not solely the result of membrane∕foulant interactions. Constant flux experiments, where the permeate flux is fixed and the TMP difference varies, minimize such variations in the hydrodynamic conditions at the membrane surface, but constant TMP difference experiments dominate the fouling literature because they are more straightforward to execute than constant flux experiments. Additionally, most industrial water purification membrane installations operate at constant flux rather than at constant TMP. Here, we describe the construction and operation of a constant flux crossflow fouling apparatus. System measurement accuracy was validated by comparison of pure water permeance measurements to values specified by the membrane manufacturer, reported elsewhere, and measured by another technique. Fouling experiments were performed with two membrane∕foulant systems: polysulfone ultrafiltration membranes with a soybean oil emulsion foulant and PVDF microfiltration membranes with a polystyrene latex bead suspension foulant. Automatic permeate flux control facilitated flux stepping experiments, which are commonly used to determine the threshold flux or critical flux of a membrane∕foulant pair. Comparison of a flux stepping experiment with a literature report yielded good agreement. PMID:23556842

  15. Energetic and molecular water permeation mechanisms of the human red blood cell urea transporter B.

    PubMed

    Azouzi, Slim; Gueroult, Marc; Ripoche, Pierre; Genetet, Sandrine; Colin Aronovicz, Yves; Le Van Kim, Caroline; Etchebest, Catherine; Mouro-Chanteloup, Isabelle

    2013-01-01

    Urea transporter B (UT-B) is a passive membrane channel that facilitates highly efficient permeation of urea. In red blood cells (RBC), while the major function of UT-B is to transport urea, it is assumed that this protein is able to conduct water. Here, we have revisited this last issue by studying RBCs and ghosts from human variants with defects of aquaporin 1 (AQP1) or UT-B. We found that UT-B's osmotic water unit permeability (pfunit) is similar to that of AQP1. The determination of diffusional permeability coefficient (Pd) allowed the calculation of the Pf/Pd ratio, which is consistent with a single-file water transport. Molecular dynamic simulations of water conduction through human UT-B confirmed the experimental finding. From these results, we propose an atomistic description of water-protein interactions involved in this permeation. Inside the UT-B pore, five water molecules were found to form a single-file and move rapidly along a channel by hydrogen bond exchange involving two critical threonines. We further show that the energy barrier for water located in the central region coincides with a water dipole reorientation, which can be related to the proton exclusion observed experimentally. In conclusion, our results indicate that UT-B should be considered as a new member of the water channel family. PMID:24376529

  16. Hydrogen-Induced Cracking Assessment in Pipeline Steels Through Permeation and Crystallographic Texture Measurements

    NASA Astrophysics Data System (ADS)

    Mohtadi-Bonab, M. A.; Karimdadashi, R.; Eskandari, M.; Szpunar, J. A.

    2016-05-01

    Electrochemical hydrogen charging and permeation techniques were used to characterize hydrogen distribution, trapping, and diffusion in X60 and X60 sour service (X60SS) pipeline steels. The results obtained contribute to better understanding of hydrogen-induced cracking (HIC). SEM observations illustrated that all HIC cracks were formed at the center of cross section in the X60 steel after 3-h hydrogen charging and length of cracks increased with charging time. No HIC cracks were recorded at the cross section of X60SS steel after the same charging for different durations. Hydrogen permeation tests showed that the density of reversible hydrogen traps was lower at the center of cross section in the X60SS steel compared to the X60 one, and this is considered as one of the main reasons for high resistance of X60SS steel to HIC. EBSD orientation imaging results proved that the accumulation of <111>||ND-oriented grains at the center of the cross section in the X60SS steel was high. This is also considered as another reason for higher resistance of this steel to HIC. Finally, the center segregation zone with higher hardness value in the X60 steel was more pronounced than in the X60SS steel which made the X60 steel susceptible to HIC cracking.

  17. A novel application of electrospinning technique in sublingual membrane: characterization, permeation and in vivo study.

    PubMed

    Chen, Jianting; Wang, Xiaoyu; Zhang, Wenji; Yu, Shihui; Fan, Jinwu; Cheng, Bingchao; Yang, Xinggang; Pan, Weisan

    2016-08-01

    Isosorbide dinitrate-polyvinylpyrrolidone (ISDN-PVP) electrospinning fibers were formulated and explored as potentially sublingual membrane. The addition of polyethylene glycol (PEG) to the formulation improved flexibility and reduced fluffiness of the fiber mat. The scanning electron microscopy (SEM) demonstrated that the fibers tended to be cross-linking, and the crosslinking degree increased with the increase of PEG amount. The differential scanning calorimetry (DSC) indicated that ISDN existed in non-crystalline state in the fibers (except at the highest drug content). The infrared spectroscopy suggested that ISDN had better compatibility with the ingredients owing to the hydrogen bonding (or hydrophobic interactions). The fibers were highly favorable for the fabrication of sublingual membrane due to neutral pH, large folding endurance and rapid drug release (complete dissolution within 120 s). The permeation study of ISDN through both dialysis membrane (DM) and porcine sublingual mucosa (SM) were carried out. A significant relationship of drug permeation rate through DM and SM was built up, which indicated that DM could be used to partly simulate SM and assess formulation. The pharmacokinetic study in rats demonstrated that the electrospinning fiber membrane had a higher Cmax and lower Tmax compared to the reference preparation, and the relative bioavailability of the fiber membrane was 151.6%. PMID:26716771

  18. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    NASA Astrophysics Data System (ADS)

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-03-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient `green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm-2h-1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  19. Drug permeation and cellular interaction of amino acid-coated drug combination powders for pulmonary delivery.

    PubMed

    Vartiainen, Ville; Bimbo, Luis M; Hirvonen, Jouni; Kauppinen, Esko I; Raula, Janne

    2016-05-17

    The effect of three amino acid coatings (L-leucine, L-valine and L-phenylalanine) on particle integrity, aerosolization properties, cellular interaction, cytocompatibility, and drug permeation properties of drug combination powder particles (beclomethasone dipropionate and salbutamol sulphate) for dry powder inhalation (DPI) was investigated. Particles with crystalline L-leucine coating resulted in intact separated particles, with crystalline L-valine coating in slightly sintered particles and with amorphous L-phenylalanine coating in strongly fused particles. The permeation of beclomethasone dipropionate across a Calu-3 differentiated cell monolayer was increased when compared with its physical mixture. Drug crystal formation was also observed on the Calu-3 cell monolayer. The L-leucine coated particles were further investigated for cytocompatibility in three human pulmonary (Calu-3, A549 and BEAS-2B) and one human macrophage (THP-1) cell lines, where they showed excellent tolerability. The l-leucine coated particles were also examined for their ability to elicit reactive oxygen species in pulmonary BEAS-2B and macrophage THP-1 cell lines. The study showed the influence of the amino acid coatings for particle formation and performance and their feasibility for combination therapy for pulmonary delivery. PMID:27034001

  20. Hydrophobic Gating of Ion Permeation in Magnesium Channel CorA

    PubMed Central

    Neale, Chris; Chakrabarti, Nilmadhab; Pomorski, Pawel; Pai, Emil F.; Pomès, Régis

    2015-01-01

    Ion channels catalyze ionic permeation across membranes via water-filled pores. To understand how changes in intracellular magnesium concentration regulate the influx of Mg2+ into cells, we examine early events in the relaxation of Mg2+ channel CorA toward its open state using massively-repeated molecular dynamics simulations conducted either with or without regulatory ions. The pore of CorA contains a 2-nm-long hydrophobic bottleneck which remained dehydrated in most simulations. However, rapid hydration or “wetting” events concurrent with small-amplitude fluctuations in pore diameter occurred spontaneously and reversibly. In the absence of regulatory ions, wetting transitions are more likely and include a wet state that is significantly more stable and more hydrated. The free energy profile for Mg2+ permeation presents a barrier whose magnitude is anticorrelated to pore diameter and the extent of hydrophobic hydration. These findings support an allosteric mechanism whereby wetting of a hydrophobic gate couples changes in intracellular magnesium concentration to the onset of ionic conduction. PMID:26181442

  1. Fabrication of electrospun nanofibres of BCS II drug for enhanced dissolution and permeation across skin.

    PubMed

    Kamble, Ravindra N; Gaikwad, Sheetal; Maske, Akhil; Patil, Sharvil S

    2016-05-01

    The present work reports preparation of irbesartan (IBS) loaded nanofibre mats using electrospinning technique. The prepared nanofibres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction analysis, in vitro diffusion and ex vivo skin permeation studies. FTIR studies revealed chemical compatibility of IBS and polyvinyl pyrrolidine (PVP K-30). SEM images confirmed formation of nanofibres wherein IBS existed in amorphous form as revealed by DSC and XRD analyses. The prepared nanofibre mats of IBS were found to be superior to IBS loaded as cast films when analysed for in vitro IBS release and ex vivo skin permeation studies since the flux of IBS loaded nanofibres was 17 times greater than as cast film. The improvement in drug delivery kinetics of IBS loaded nanofibres could be attributed to amorphization with reduction in particle size of IBS, dispersion of IBS at molecular level in PVP matrix and enormous increase in the surface area for IBS release due to nanonization. Thus transdermal patch of IBS loaded nanofibres can be considered as an alternative dosage form in order to improve its biopharmaceutical properties and enhance therapeutic efficacy in hypertension. PMID:27222753

  2. Fabrication of electrospun nanofibres of BCS II drug for enhanced dissolution and permeation across skin

    PubMed Central

    Kamble, Ravindra N.; Gaikwad, Sheetal; Maske, Akhil; Patil, Sharvil S.

    2016-01-01

    The present work reports preparation of irbesartan (IBS) loaded nanofibre mats using electrospinning technique. The prepared nanofibres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction analysis, in vitro diffusion and ex vivo skin permeation studies. FTIR studies revealed chemical compatibility of IBS and polyvinyl pyrrolidine (PVP K-30). SEM images confirmed formation of nanofibres wherein IBS existed in amorphous form as revealed by DSC and XRD analyses. The prepared nanofibre mats of IBS were found to be superior to IBS loaded as cast films when analysed for in vitro IBS release and ex vivo skin permeation studies since the flux of IBS loaded nanofibres was 17 times greater than as cast film. The improvement in drug delivery kinetics of IBS loaded nanofibres could be attributed to amorphization with reduction in particle size of IBS, dispersion of IBS at molecular level in PVP matrix and enormous increase in the surface area for IBS release due to nanonization. Thus transdermal patch of IBS loaded nanofibres can be considered as an alternative dosage form in order to improve its biopharmaceutical properties and enhance therapeutic efficacy in hypertension. PMID:27222753

  3. Quantitative monitoring of membrane permeation via in-situ ATR FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Beckingham, Bryan; Miller, Daniel

    Ion conducting membranes are of interest for various energy applications including fuel cells and artificial photosynthesis systems. Within the context of artificial photosynthesis, membranes are desired that facilitate the ion transport necessary to feed the electrochemical reactions while meeting various additional selectivity and permeability demands depending on the CO2 reduction products. Herein, we demonstrate the use of in-situ ATR FT-IR spectroscopy to quantitatively resolve the concentration of single and multicomponent mixtures of various CO2 reduction products including methanol, formate and acetate. We then apply this methodology to the in-situ monitoring of the permeation of single and multicomponent mixtures across commercially available membranes. Membrane permeabilities and selectivities calculated from the single component time-resolved concentration curves are compared to the multicomponent permeation experiments. This material is based upon work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC000493.

  4. Selectivity and permeation of alkali metal ions in K+-channels.

    PubMed

    Furini, Simone; Domene, Carmen

    2011-06-24

    Ion conduction in K(+)-channels is usually described in terms of concerted movements of K(+) progressing in a single file through a narrow pore. Permeation is driven by an incoming ion knocking on those ions already inside the protein. A fine-tuned balance between high-affinity binding and electrostatic repulsive forces between permeant ions is needed to achieve efficient conduction. While K(+)-channels are known to be highly selective for K(+) over Na(+), some K(+) channels conduct Na(+) in the absence of K(+). Other ions are known to permeate K(+)-channels with a more moderate preference and unusual conduction features. We describe an extensive computational study on ion conduction in K(+)-channels rendering free energy profiles for the translocation of three different alkali ions and some of their mixtures. The free energy maps for Rb(+) translocation show at atomic level why experimental Rb(+) conductance is slightly lower than that of K(+). In contrast to K(+) or Rb(+), external Na(+) block K(+) currents, and the sites where Na(+) transport is hindered are characterized. Translocation of K(+)/Na(+) mixtures is energetically unfavorable owing to the absence of equally spaced ion-binding sites for Na(+), excluding Na(+) from a channel already loaded with K(+). PMID:21540036

  5. Helium permeation through a-C:H films deposited on polymeric substrates

    NASA Astrophysics Data System (ADS)

    Valentini, L.; Bellachioma, M. C.; Lozzi, L.; Santucci, S.; Kenny, J. M.

    2002-09-01

    The influence of amorphous hydrogenated carbon a-C:H coatings on gas permeation through polymer films was investigated. Hydrogenated amorphous carbon (a-C:H) films were deposited, at room temperature, from a CH4/Ar plasma produced by a radio frequency glow discharge system at 13.56 MHz. Polyether-etherketone (PEEK) and polyetherimide foils with different thicknesses were used as substrates. The permeation of He was measured and the reduction of the permeability coefficient is correlated here to the composition and density of the a-C:H films. The density and film structure of the layers were analyzed using x-ray reflectivity and Raman spectroscopy of films deposited onto silicon reference samples. A less pronounced reduction of the permeability coefficients for hard, dense diamond-like layers is reported with respect to those obtained for soft, polymer-like layers on PEEK substrates. Surprisingly, the barrier efficacy of the coating decreases with an increase in a-C:H film density. This unexpected result is attributed to intrinsic stress and the corresponding formation of microcracks. The effect of nitrogen incorporation, which reduces film permeability, is investigated in terms of the stress relaxation mechanism promoted. copyright 2002 American Vacuum Society.

  6. Photoswitchable gas permeation membranes based on azobenzene-doped liquid crystals

    NASA Astrophysics Data System (ADS)

    Glowacki, Eric; Marshall, Kenneth L.; Tang, Ching W.

    2009-08-01

    We have fabricated switchable gas permeation membranes in which a photoswitchable low-molecular-weight liquid crystalline (LC) material acts as the active element. Two different LC eutectic mixtures based on cyanobiphenyls and phenyl benzoates, respectively, were doped with mesogenic azo dyes and infused into commercially available tracketched porous polycarbonate membranes with regular cylindrical pores (0.40 to 10.0 μm). Photo-induced isothermal phase changes in the imbibed mesogenic material afforded large, reversible changes in the permeability of the photoswitchable membrane to nitrogen. The membrane imbibed with the photoswitchable cyanobiphenyl LC material demonstrated low permeability in the nematic state, while the photogenerated isotropic state demonstrated a 16×-greater sorption coefficient. Both states obey a high linear sorption behavior in accordance with Henry's Law. The membrane imbibed with the photoswitchable phenyl benzoate LC showed the opposite permeability behavior to the biphenylimbibed membrane, along with nonlinear sorption behavior. Permeability switching response times for the membranes on the order of 5 s were demonstrated using alternating UV and >420-nm radiation at an intensity of 2 mW/cm2. The effect of thermomolecular motion on gas sorption and diffusion over the LC-isotropic phase transitions are, for the first time, evaluated under isothermal conditions. These photoswitchable membranes are the first examples of systems that are capable of rapid and reversible gas permeation switching. Such switchable and/or tunable membranes are in high demand for applications in analytics, screening, and membrane reactors.

  7. Calcium Ion Flow Permeates Cells through SOCs to Promote Cathode-Directed Galvanotaxis

    PubMed Central

    Guo, Liang; Xu, Chunyan; Li, Dong; Zheng, Xiulan; Tang, Jiebing; Bu, Jingyi; Sun, Hui; Yang, Zhengkai; Sun, Wenjing; Yu, Xiaoguang

    2015-01-01

    Sensing and responding to endogenous electrical fields are important abilities for cells engaged in processes such as embryogenesis, regeneration and wound healing. Many types of cultured cells have been induced to migrate directionally within electrical fields in vitro using a process known as galvanotaxis. The underlying mechanism by which cells sense electrical fields is unknown. In this study, we assembled a polydimethylsiloxane (PDMS) galvanotaxis system and found that mouse fibroblasts and human prostate cancer PC3 cells migrated to the cathode. By comparing the effects of a pulsed direct current, a constant direct current and an anion-exchange membrane on the directed migration of mouse fibroblasts, we found that these cells responded to the ionic flow in the electrical fields. Taken together, the observed effects of the calcium content of the medium, the function of the store-operated calcium channels (SOCs) and the intracellular calcium content on galvanotaxis indicated that calcium ionic flow from the anode to the cathode within the culture medium permeated the cells through SOCs at the drift velocity, promoting migration toward the cathode. The RTK-PI3K pathway was involved in this process, but the ROCK and MAPK pathways were not. PC3 cells and mouse fibroblasts utilized the same mechanism of galvanotaxis. Together, these results indicated that the signaling pathway responsible for cathode-directed cellular galvanotaxis involved calcium ionic flow from the anode to the cathode within the culture medium, which permeated the cells through SOCs, causing cytoskeletal reorganization via PI3K signaling. PMID:26447479

  8. Dust-acoustic waves and stability in the permeating dusty plasma. II. Power-law distributions

    SciTech Connect

    Gong Jingyu; Du Jiulin; Liu Zhipeng

    2012-08-15

    The dust-acoustic waves and the stability theory for the permeating dusty plasma with power-law distributions are studied by using nonextensive q-statistics. In two limiting physical cases, when the thermal velocity of the flowing dusty plasma is much larger than, and much smaller than the phase velocity of the waves, we derived the dust-acoustic wave frequency, the instability growth rate, and the instability critical flowing velocity. As compared with the formulae obtained in part I [Gong et al., Phys. Plasmas 19, 043704 (2012)], all formulae of the present cases and the resulting plasma characteristics are q-dependent, and the power-law distribution of each plasma component of the permeating dusty plasma has a different q-parameter and thus has a different nonextensive effect. Further, we make numerical analyses of an example that a cometary plasma tail is passing through the interplanetary space dusty plasma and we show that these power-law distributions have significant effects on the plasma characteristics of this kind of plasma environment.

  9. Hydrophobic Gating of Ion Permeation in Magnesium Channel CorA.

    PubMed

    Neale, Chris; Chakrabarti, Nilmadhab; Pomorski, Pawel; Pai, Emil F; Pomès, Régis

    2015-07-01

    Ion channels catalyze ionic permeation across membranes via water-filled pores. To understand how changes in intracellular magnesium concentration regulate the influx of Mg2+ into cells, we examine early events in the relaxation of Mg2+ channel CorA toward its open state using massively-repeated molecular dynamics simulations conducted either with or without regulatory ions. The pore of CorA contains a 2-nm-long hydrophobic bottleneck which remained dehydrated in most simulations. However, rapid hydration or "wetting" events concurrent with small-amplitude fluctuations in pore diameter occurred spontaneously and reversibly. In the absence of regulatory ions, wetting transitions are more likely and include a wet state that is significantly more stable and more hydrated. The free energy profile for Mg2+ permeation presents a barrier whose magnitude is anticorrelated to pore diameter and the extent of hydrophobic hydration. These findings support an allosteric mechanism whereby wetting of a hydrophobic gate couples changes in intracellular magnesium concentration to the onset of ionic conduction. PMID:26181442

  10. A UHPLC-UV Method to Quantify Skin Deposition and Transdermal Permeation of Tizanidine Hydrochloride.

    PubMed

    Del Río-Sancho, Sergio; Merino, Virginia; López-Castellano, Alicia; Kalia, Yogeshvar N

    2016-05-01

    Tizanidine hydrochloride is an α2-adrenergic agonist used for the symptomatic relief of spasticity associated with multiple sclerosis or with spinal cord injury or disease. The objective of this study was to develop an isocratic, robust and sensitive ultra-high performance liquid chromatography method using UV detection for use in a project to develop a transdermal therapeutic system to deliver tizanidine across the skin. Isocratic separation was achieved using a C18column and a mobile phase comprising a 80:20 mixture of 0.004% trifluoroacetic acid in water and MeCN (pH* 3.2) at a flow rate of 0.2 mL min(-1) Tizanidine eluted at 1.499 min and the total run time was 2 min. The method was specific, robust and the response was accurate, precise and linear from 17.4 to 290 ng mL(-1) In contrast to existing methods, the method developed here was validated over a concentration range so as to include the low concentrations frequently observed in transdermal permeation studies and in samples extracted from the cutaneous matrix. Its suitability for use in transdermal permeation studies was subsequently tested and confirmed in preliminary experiments using porcine skinin vitro. PMID:26892401

  11. Polyimide-silica composite materials: How does silica influence their microstructure and gas permeation properties?

    SciTech Connect

    Joly, C.; Smaihi, M.; Porcar, L.; Noble, R.D.

    1999-09-01

    Composite polyimide-silica materials have been synthesized via the sol-gel process and their gas transport properties studied. Structural characterizations have been performed showing that materials prepared with large concentration of silicon alkoxyde are composites made of silica particles embedded in the polyimide matrix while low-silicon alkoxyde concentration induces homogeneous materials. X-ray diffraction shows that the presence of silicon species induces modifications in the microstructure of the polyimide chains. These modifications have been confirmed by a shift of the glass transition temperature and density variations. Influence of the temperature and silicon species on the gas transport have been studied using various gases (nitrogen, oxygen, carbon dioxide, and methane) showing that gas permeation coefficients increase with the silicon species proportion. CO{sub 2} sorption measurements have been performed at various temperatures and the results have been analyzed in terms of the dual sorption theory. Activation energies have been calculated for the permeation and sorption mechanisms. The results show that silicon species contributes to the overall permeability.

  12. Mechanism of gas permeation through polymer membranes. Progress report, June 1, 1979-March 31, 1980

    SciTech Connect

    Stern, S.A.; Kulkarni, S.S.; Mauze, G.R.

    1980-04-01

    The objective is to assess the validity of a free-volume model of gas permeation through nonporous polymeric membranes (5-7). During the past report period, diffusion and solubility coefficients for CO/sub 2/, C/sub 2/H/sub 4/, and C/sub 3/H/sub 8/ in polyethylene rods have been measured at temperatures from 5/sup 0/ to 35/sup 0/C and at pressures of up to 30 atm. Characteristic free-volume parameters were determined from these data by means of an improved computational technique. The parameters were used to predict permeability coefficients for the transport of the above gases through polyethylene membranes. The theoretical permeability coefficients were found to be in very satisfactory agreement with experimental values obtained from independent permeability measurements. Rates of permeation have also been measured for 50% CO/sub 2/-50% C/sub 2/H/sub 4/, 74.9% CO/sub 2/-25.1% C/sub 2/H/sub 4/, and 50% CO/sub 2/-50% C/sub 3/H/sub 8/ mixtures between 20 and 50/sup 0/C and at pressures of up to 28 atm. The permeability coefficients for the components of the mixtures were found to be higher than those of the pure gases, as predicted by the free-volume model.

  13. HUMAN SKIN PERMEATION OF 3-O-ALKYL CARBAMATE PRODRUGS OF NALTREXONE

    PubMed Central

    Vaddi, Haranath K.; Banks, Stan L.; Chen, Jianhong; Hammell, Dana C.; Crooks, Peter A.; Stinchcomb, Audra L.

    2009-01-01

    N-Monoalkyl and N,N-dialkyl carbamate prodrugs of naltrexone (NTX), an opioid antagonist, were synthesized and their in vitro permeation across human skin was determined. Relevant physicochemical properties were also determined. Most prodrugs exhibited lower melting points, lower aqueous solubilities, and higher oil solubilities than NTX. The flux values from N-monoalkyl carbamate prodrugs were significantly higher than those from NTX and N,N-dialkyl carbamates. The melting points of N-monoalkyl carbamate prodrugs were quite low compared to the N,N-dialkyl carbamate prodrugs and NTX. Heats of fusion for the N,N-dialkyl carbamate prodrugs were higher than that for NTX. N-Monoalkyl carbamate prodrugs had higher stratum corneum/vehicle partition coefficients than their N,N-dialkyl counterparts. Higher percent prodrug bioconversion to NTX in skin appeared to be related to increased skin flux. N,N-Dialkyl carbamate prodrugs were more stable in buffer and in plasma than N-monoalkyl carbamate prodrugs. In conclusion, N-monoalkyl carbamate prodrugs of NTX improved the systemic delivery of NTX across human skin in vitro. N,N-Dialkyl substitution in the prodrug moiety decreased skin permeation and plasma hydrolysis to the parent drug. The cross-sectional area of the carbamate head group was the major determinant of flux of the N-monoalkyl and N,N-dialkyl carbamate prodrugs of NTX. PMID:18972573

  14. Positive impact of biofilm on reducing the permeation of ampicillin through membrane for membrane bioreactor.

    PubMed

    Shen, Liang; Yuan, Xia; Shen, Weihuang; He, Ning; Wang, Yuanpeng; Lu, Haoliang; Lu, Yinghua

    2014-02-01

    The membrane bioreactor (MBR) has recently been the focus of research for the treatment of emerging contaminants such as antibiotics in wastewater. Although the biofilm on membrane in an MBR has been considered a cause of "membrane biofouling", its positive impact on removing pollutants has not been well-studied. This study was designed to investigate the retention effect on the permeation of ampicillin (AMP) by the biofilm coated on cellulose acetate (CA) membrane (commonly used for MBRs) utilizing a novel method based on microbial sensitivity test. The bioflim layer (thickness of 12-16μm) increased the resistance of the membrane for AMP permeation by 3-28%. Diffusion appeared to be the main driving force for the mass transfer of AMP across the membrane. Besides, the biofilm increased the retention of AMP by 23% but exhibited similar adsorption capacity with comparison of the suspended activated sludge, which indicates that the compact structure of the biofilm was the major contributor for the added retention effect on AMP by the biofilm-coated CA membrane. This study suggests that biofilm (biofouling) in MBRs increases the retention of small-molecule constituents such as antibiotics. A delicate tradeoff between reduced wastewater throughput and increased retention of contaminants should be obtained when an MBR is designed and operated. PMID:24268345

  15. Correlation of Structure and Function for CO2 Permeation in Polyphosphazene Membranes

    SciTech Connect

    Frederick F. Stewart; Christopher J. Orme

    2005-10-01

    Polyphosphazenes are an intriguing class of polymers because molecular substitutions can be made onto the phosphorus and nitrogen backbone after polymerization. Chemical functionality is supplied through selection of pendant group. In general, regardless of pendant group, polyphosphazenes embody a high degree of thermal and chemical stability, although some pendant groups yield more stable polymers as compared to others. For example, many aryloxyphosphazene formulations are stable at temperatures as high as 300 - 400 degrees Celsius, while many alkoxy-substituted polymers decompose at lower temperatures. It has been thought that permeation of the more condensable gases, such as CO2 and H2S, could be enhanced by selection of pendant groups that exhibit higher affinities for these gases. In this paper, over 20 polyphosphazenes with a wide array of pendant groups will be discussed in terms of their CO2 transport properties. From this work, we have concluded that the chemical characteristics of the pendant group largely do not play a role in CO2 or permanent gas transport. More important are the physical characteristics of the polymer. For example, permeabilities were found to correlate well to the glass transition temperature of the polymer, regardless of the polarity of the pendant group. Thus, segmental chain motion and physical state of the polymer appear to play a more dominant role. This result differs sharply from data taken from liquid transport data that suggests a strong similarity in the solubility properties between the permeant and the polymer is required for higher permeation rates.

  16. A quantitative study of aromatic amine permeation through protective gloves using amine adsorptive pads.

    PubMed

    Vo, E; Berardinelli, S P; Hall, R C; El Ayouby, N

    2000-01-01

    A quantitative study of aromatic amine permeation through a glove material using Permea-Tec aromatic amine pads, used for the detection of chemical breakthrough of protective clothing, was performed for aniline following the microwave extraction process and gas chromatographic analysis. Aniline exhibited >99% adsorption on the pads at a spiking level of 1.94 mg (1.9 microL). Aniline showed recoveries from 65 to 89% (RSD < or =5.6%) over the range 1.1-1.9 microL (1.12-1.94 mg) of aniline applied to pads. The modified ASTM F739 and direct permeability testing procedures were used to determine breakthrough times for five protective glove materials using aniline as a challenge chemical. Breakthrough times for six protective gloves were determined, ranging from 182 sec to 82 min. The quantitative concentration of aniline on the pads following permeation through the gloves also was determined, ranging from 0.53 to 0.55 mg/cm2 (1.79-1.88 mg/pad). PMID:11192217

  17. Enhancement of Mycophenolate Mofetil Permeation for Topical Use by Eucalyptol and N-Methyl-2-pyrrolidone

    PubMed Central

    Songkram, Chalermkiat

    2016-01-01

    Mycophenolate mofetil (MMF) is a prodrug of mycophenolic acid (MPA) which can be metabolized by esterase. MMF has been approved by the United States Food and Drug Administration (USFDA) for treatment of psoriasis patient with skin symptoms. However, it remains unclear whether MMF is efficiently effective to treat skin symptoms developed from psoriasis. The insufficient amount of MMF penetrating through the skin results in the treatment failure due to the difficulty in MMF penetration through the stratum corneum. Skin permeation enhancers such as eucalyptol (EUL) and N-methyl-2-pyrrolidone (NMP) potentially aid in increasing skin penetration. This study aimed to investigate the effects of a concentration ratio (% w/v) between two enhancers (EUL and NMP). The results showed that EUL enhanced MMF permeation with an enhancement ratio (ER) of 3.44 while NMP was not able to promote the penetration of MMF. Interestingly, the synergistic effect of the two enhancers was observed with a suitable ratio given that the ER was 8.21. EUL and NMP are promising enhancers for the development of MMF based skin product. PMID:27069715

  18. Tritium permeation through steam generator tubing of helium-cooled ceramic breeder blankets

    SciTech Connect

    Fuetterer, M.; Raepsaet, X.; Proust, E.

    1994-12-31

    The potential sources of tritium contamination of the helium-coolant of ceramic breeder blankets have been evaluated in a previous paper for the specific case of the European BIT DEMO blanket. This evaluation associated with a rough assessment of the permeability to tritium of the tubing of helium-heated steam generators confirmed that the control of tritium losses to the steam circuit is a critical issue for this class of blanket requiring developments in three areas: (1) permeation barriers, (2) tritium recovery processes maintaining a very low concentration in tritiated species in the coolant, and (3) methods for controlling the chemistry of the coolant. Consequently, in order to define the specifications of these developments, a detailed evaluation of the permeability to tritium of helium-heated steam generators (SGs) was performed, which will be reported in this paper. This study includes the definition of the thermal-hydraulic operating conditions of the SGs through thermodynamic cycle calculations, and its thermal-hydraulic design. The obtained geometry, area and temperature profiles along the tubes are then used to estimate, based on relevant permeability data, the tritium permeation through the SG as a function of the composition in tritiated species of the coolant. The implications of these results, in terms of requirements for the considered tritium control methods, will also be discussed on the basis of expected limits in tritium release to the steam circuit.

  19. In vitro permeation studies of phenolics from horse chestnut seed gels prepared with different polyacrylic acid polymer derivatives.

    PubMed

    Zelbienė, Eglė; Draksiene, Gailute; Savickas, Arunas; Kopustinskiene, Dalia; Masteikova, Ruta; Bernatoniene, Jurga

    2015-06-01

    The aim of this study was to investigate the effects of polyacrylic acid polymers (Ultrez 10, Ultrez 20, Carbopol 980, and Carbopol 940) on the viscosity and the in vitro permeation of phenolic compounds from the gel prepared from natural horse chestnut seed extract. Experiments were performed in the presence and in the absence of peppermint oil (Mentha piperita). Our results showed that peppermint oil decreased the viscosity of the gels and permeation of phenolic compounds from all gel samples. Results show that the highest content of phenolic compounds (1.758 μg cm(-2)) permeated in vitro from gel based on Carbopol Ultrez 20 without peppermint oil added (p<0.05 vs. other tested polymers). PMID:26011934

  20. MD simulation study of direct permeation of a nanoparticle across the cell membrane under an external electric field

    NASA Astrophysics Data System (ADS)

    Shimizu, Kenta; Nakamura, Hideya; Watano, Satoru

    2016-06-01

    Nanoparticles (NPs) have been attracting much attention for biomedical and pharmaceutical applications. In most of the applications, NPs are required to translocate across the cell membrane and to reach the cell cytosol. Experimental studies have reported that by applying an electric field NPs can directly permeate across the cell membrane without the confinement of NPs by endocytic vesicles. However, damage to the cell can often be a concern. Understanding of the mechanism underlying the direct permeation of NPs under an external electric field can greatly contribute to the realization of a technology for the direct delivery of NPs. Here we investigated the permeation of a cationic gold NP across a phospholipid bilayer under an external electric field using a coarse-grained molecular dynamics simulation. When an external electric field that is equal to the membrane breakdown intensity was applied, a typical NP delivery by electroporation was shown: the cationic gold NP directly permeated across a lipid bilayer without membrane wrapping of the NP, while a persistent transmembrane pore was formed. However, when a specific range of the electric field that is lower than the membrane breakdown intensity was applied, a unique permeation pathway was exhibited: the generated transmembrane pore immediately resealed after the direct permeation of NP. Furthermore, we found that the affinity of the NP for the membrane surface is a key for the self-resealing of the pore. Our finding suggests that by applying an electric field in a suitable range NPs can be directly delivered into the cell with less cellular damage.Nanoparticles (NPs) have been attracting much attention for biomedical and pharmaceutical applications. In most of the applications, NPs are required to translocate across the cell membrane and to reach the cell cytosol. Experimental studies have reported that by applying an electric field NPs can directly permeate across the cell membrane without the confinement of