| 1. |
- Hedlund, Jonas, et al.
(författare)
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Permporometry analysis of zeolite membranes
- 2009
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 345:1-2, s. 276-287
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Tidskriftsartikel (refereegranskat)abstract
- In permporometry analysis of zeolite membranes, the permeance of a non-adsorbing gas, such as helium, is measured as a function of pressure of a strongly adsorbing compound, such as n-hexane in the case of silicalite-1 membranes. The adsorbing compound effectively blocks the transport of the non-adsorbing gas already at very low activity of the adsorbing compound. The plot of the permeance of the non-adsorbing gas as a function of relative pressure of the adsorbing compound is denoted a permporometry pattern. The present work is based on experimental data for a number of thin MFI membranes with a film thickness ranging from 300 to 1800 nm. An adsorption-branch permporometry experiment is simple and straightforward and after activation of the membrane by removing adsorbed species at 300 °C in a flow of dry gas, a full permporometry pattern is recorded within about 7 h for such membranes. It is shown how the distribution of flow-through defects can be estimated from the permporometry pattern using a simple model for permeation based on Knudsen diffusion. The estimated defect distribution is supported by SEM observations. In addition, the permeance of the non-adsorbing gas through defects measured in permporometry can be used to predict the permeance of molecules diffusing through defects in the membrane in mixture separation experiments and also indicate the separation factor. For instance, the helium permeance through defects in an MFI membrane measured by helium/n-hexane permporometry at room temperature can be used to estimate the permeance of 2,2-dimethylbutane (DMB) in a mixture separation experiment at a higher temperature with a feed containing both DMB and n-hexane by assuming Knudsen diffusion for both helium and DMB in the defects. Also, the separation factor αn-hexane/DMB in a mixture separation experiment at a certain temperature with an MFI membrane with a given defect distribution can be estimated from n-hexane/helium permporometry data recorded at the same temperature through an empirical correlation. In summary, adsorption-branch permporometry is a very effective tool for analysis of thin zeolite membranes, that in short time gives data that can be used to estimate the distribution of flow-through defects in the membrane and to estimate the transport of large molecules through defects in separation experiments and also estimate separation performance.
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| 2. |
- Lindmark, Jonas, et al.
(författare)
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Carbon dioxide removal from synthesis gas using MFI membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 360:1-2, s. 284-291
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Tidskriftsartikel (refereegranskat)abstract
- A membrane processes may represent a more effective alternative compared to current technology for separation of CO2 from synthesis gas. In the present work, MFI membranes were prepared and the separation performance was evaluated. The Si/Al ratio and the counter ions in the membrane had a significant effect on both single gas permeation and mixture separation by modifying both the effective pore size and the adsorption properties of the membranes. The membranes were relatively unselective for binary mixtures of carbon dioxide and hydrogen, but when the feed also contained water, a CO2/H2 separation factor of 6.2 was achieved for a BaZSM-5 membrane at room temperature. The CO2 permeance for this membrane was as high as 13·10-7 mol · m-2 · s-1 · Pa-1. A suitable terminology for this effect, that a third component, in this case water, enhanced the separation of two other components, in this case CO2 and H2, is sorption enhanced separation. Due to the reduced adsorption of both CO2 and water at higher temperature, the CO2/H2 separation factor was always reduced as the temperature was increased. This work clearly shows that MFI membranes are promising candidates for CO2 separation from synthesis gas.
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| 3. |
- Lindmark, Jonas, et al.
(författare)
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Impregnation of zeolite membranes for enhanced selectivity
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 365:1-2, s. 188-197
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Tidskriftsartikel (refereegranskat)abstract
- A new method to enhance the selectivity of zeolite membranes for alternative separation tasks has been developed. Calcined MFI membranes were impregnated with a solution of Ca(NO3)2 in methanol and calcined at 600 °C to thermally decompose the nitrate. SEM and EDS data indicated that calcium compounds were evenly distributed in the entire MFI film and in addition, a few crystals of a calcium compound were observed on top of the film in some locations. A HR-TEM investigation showed that calcium compounds were present in low concentration in the sample and that the interiors of the MFI crystals remained fully crystalline after impregnation and calcination. However, the HR-TEM investigation could neither confirm nor rule out the occurrence of calcium compounds in the pores in the interiors of the crystals. In accordance with the SEM and TEM observations, XRD data showed that calcium compounds on top of the film were relatively large CaCO3 crystals and that the zeolite film remained crystalline after impregnation. However, eventual calcium compounds in the pores of the zeolite could not be studied by XRD since these would probably generate a very weak signal of amorphous material. FTIR data indicated that impregnation increased the amount of both physisorbed and chemisorbed CO2, the latter resulting in carbonate species in the film. n-Hexane/helium adsorption branch permporometry showed that the high quality of the membranes remained after modification. The single component permeance ratio CO2/H2 increased from 0.6 to 1.5 after impregnation. Calculations indicated that the increased CO2/H2 single component permeance ratios were both an effect of increased adsorption of CO2 in the film and reduced pressure drop in the support. The dual component separation factor α CO2/H2 at room temperature increased drastically from 0.7 (H2 selective) to 3.4 (CO2 selective) after impregnation. This work shows for the first time that impregnation procedures can be used to tailor the diffusion properties of zeolite membranes in a similar way as impregnation procedures are used to tailor the catalytic performance of catalysts.
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| 4. |
- Lindmark, Jonas, et al.
(författare)
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Modification of MFI membranes with amine groups for enhanced CO2 selectivity
- 2010
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Ingår i: Journal of Materials Chemistry. - 0959-9428 .- 1364-5501. ; 20:11, s. 2219-2225
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Tidskriftsartikel (refereegranskat)abstract
- Much research on zeolite membranes has been devoted to MFI type zeolite and these membranes can be prepared reproducibly with high quality by our group. However, the MFI pores are too large for separation of small molecules such as CO2, H-2 CH4, and H2O by molecular sieving and the CO2 affinity is not sufficiently strong in our current membranes with quite high Si/Al ratio to achieve CO2 selective membranes. In the present work, existing MFI membranes with high Si/Al ratio are modified with methylamine to increase the CO2 affinity and thus increase the CO2 selectivity. To the best of our knowledge, this is the first time this type of modification is reported for zeolite membranes. These membranes were then evaluated for separation of CO2 from various mixtures of CO2, H-2, CH4 and H2O. The modification had significant effects on both permeances and separation factors and the selectivity towards CO2 was increased considerably for all the feed mixtures tested. The highest separation factor was observed for a CO2/CH4/H2O mixture and alpha-CO2/CH4 was 12 at about 40 degrees C. At the same time, the CO2 permeance was as high as 9 x 10(-7) mol m(-2) s(-1) Pa-1. The separation factor for the amine-modified silicalite-1 membranes was comparable to the highest reported separation factors for MFI membranes, while the CO2 permeance was higher than reported for other selective MFI membranes.
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| 5. |
- Lindmark, Jonas, et al.
(författare)
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Separation of CO2 and H2 with modified MFI membranes
- 2007
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Ingår i: From Zeolites to Porous MOF Materials. - Amsterdam : Elsevier. - 9780444531858 ; , s. 975-980
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Konferensbidrag (refereegranskat)abstract
- MFI membranes with equal film thickness were grown on graded alumina supports and modified by ion exchange or impregnation. Single gas permeances of CO2 and H2 were measured for all membranes. Both impregnation and ion exchange had a significant effect on the permeation properties of the membranes. The single gas CO2/H2 permeance ratios were 0.57, 0.82, 1.7 and 2.2 for silicalite-1, NaZSM-5, BaZSM-5 and silicalite-1 impregnated with Ca(NO3)2 , respectively. Selected membranes were tested for separation of a mixture of 90 kPa CO2 and 90 kPa H2 in the temperature range 25-400 °C. The separation factors at 25 °C were 0.7, 2.0 and 4.1 for silicalite-1, BaZSM-5 and impregnated silicalite-1, respectively and decreased with increasing temperature. The results show that the separation factor can be enhanced significantly by impregnation, lowering of the Si/Al ratio or ion exchange.
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| 6. |
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| 7. |
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| 8. |
- Perdana, Indra, 1973, et al.
(författare)
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Influence of NOx adsorbed species on component permeation through ZSM-5 membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 349:1-2, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- A thin ZSM-5 film was grown on an alpha-alumina support, resulting in a composite membrane. The membraneswere characterized by SEM and adsorption branch n-hexane/helium permporometry. In addition,the permeation of gas mixtures containing NO2, NO, N2 and argon was evaluated. The effect of temperatureand gas mixture composition on the component permeation and selectivity was investigated.It was found that NOx permeation through the ZSM-5 membrane was partially surface concentrationdependent and was thermally activated. However, transport by gas translational diffusion seemed todominate at the conditions studied. The presence of various NOx adsorbed species appeared to influencediffusion of NO2 in ZSM-5 and reduced transport of other inert and weakly adsorbed components overa wide temperature range (20–400◦C). Strongly adsorbed surface nitrate species formed in the presenceof gas phase NOx should be responsible for the reduced transport of these components at the elevatedtemperature. The findings are of interest for possible applications of ZSM-5 membranes for componentseparation at high temperature.
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| 9. |
- Rezai, Seyed Alireza Sadat, et al.
(författare)
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Water/hydrogen/hexane multicomponent selectivity of thin MFI membranes with different Si/Al ratios
- 2008
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 108:1-3, s. 136-142
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Tidskriftsartikel (refereegranskat)abstract
- MFI films with a thickness of about 550 nm were prepared on α-alumina substrates. The surface Si/Al ratios (XPS) were 157 and 62 for silicalite-1 and ZSM-5 films, respectively, and in accordance, XRD data indicated lower ratios for ZSM-5 films. Higher ratios were observed by ICP-AES for crystals grown in the bulk of the synthesis mixtures. Six membranes of each type were prepared. Porosimetry measurements showed that all membranes were of high and similar quality. Single gas permeances for H2, N2, He, CO2 and SF6 at 25 °C were very similar within each type of membranes. However, the average hydrogen permeance was 27% lower and the average H2/SF6 single gas permeance ratio was 67% higher for ZSM-5 membranes. These differences are attributed to a narrower effective pore diameter for the ZSM-5 membranes due to the sodium counter ions. Separation of mixtures of H2O, H2 and n-hexane (helium balance) was investigated in the temperature range 25-350 °C. The highest separation factors α-H2O/H2 were observed at 25 °C and were 14.3 and 19.7 for silicalite-1 and ZSM-5, respectively. The membranes were selective also at 100 °C and the separation factors were about 3.2 and 6 for silicalite-1 and ZSM-5, respectively. However, the selectivity decreased at elevated temperatures and the separation factor approached 1 at temperatures above 180 °C for both membrane types. The observed water selectivity was attributed to weak adsorption of water on polar sites. A low (1.5-3) α-H2O/n-C6 separation factor was observed for both membrane types for the entire investigated temperature range.
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| 10. |
- Sandström, Linda, et al.
(författare)
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Separation of methanol and ethanol from synthesis gas using MFI membranes
- 2010
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 360:2, s. 265-275
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Tidskriftsartikel (refereegranskat)abstract
- Methanol or ethanol production from synthesis gas is limited by thermodynamic equilibrium and separation of the alcohol product in or near the reactor at reaction conditions (about 250° C and 50 bar) could improve the process. Separation of methanol and ethanol from synthesis gas by MFI membranes with two different Si/Al ratios has therefore been evaluated in the present work. The synthesis gas was represented by hydrogen, carbon dioxide and water, and membrane separation performance was evaluated at atmospheric pressure and varying temperatures.The highest measured methanol/hydrogen separation factor, 32, was observed for the more polar membrane type with the lowest Si/Al ratio, while the highest ethanol/hydrogen separation factor, 46, was observed for the less polar membrane type with the highest Si/Al ratio, both at room temperature. The separation was controlled by adsorption, and consequently, the separation factors were reduced as the temperature increased, since the feed composition was kept constant.The methanol and ethanol permeances were about 10x10-7 mol m-2 s-1 Pa-1 independent of feed composition, membrane type or temperature, which is more than three times higher than previously reported for gas phase separation using zeolite membranes.A simple mathematical model was successfully fitted to the experimental data. The model suggests that membrane selectivity is temperature dependent, as also observed experimentally, but independent of feed pressure. Experimental data and mathematical modelling thus suggest that the membranes would be alcohol selective at reaction pressure (50 bar) and room temperature, but not at reaction temperature (250°C).
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| 11. |
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| 12. |
- Thoresen, Petter Paulsen, et al.
(författare)
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On the understanding of bio-oil formation from the hydrothermal liquefaction of organosolv lignin isolated from softwood and hardwood sawdust
- 2023
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Ingår i: Sustainable Energy & Fuels. - : Royal Soc Chemistry. - 2398-4902. ; 7:22, s. 5361-5373
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Tidskriftsartikel (refereegranskat)abstract
- Conversion of organosolv lignins isolated with and without an inorganic acid catalyst (H2SO4) from hard- and softwood (birch and spruce) into bio-oil through hydrothermal liquefaction has been investigated. Furthermore, fractions of the isolated bio-oils were catalytically deoxygenated to improve the bio-oil properties. As elucidated through NMR, both biomass source and extraction mode influence the bio-oil product distribution. Depending on whether the lignins carry a high content of native structures, or are depolymerized and subsequently condensed in the presence of sugar dehydration products, will dictate heavy oil (HO) and light oil (LO) distribution, and skew the HO product composition, which again will influence the requirements upon catalytical deoxygenation.
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| 13. |
- Wirawan, Sang, 1973, et al.
(författare)
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H2/CO2 permeation through a silicalite-1 composite membrane
- 2011
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 375, s. 313-322
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Tidskriftsartikel (refereegranskat)abstract
- Single and binary H2/CO2 gas permeation was studied through a silicalite-1 composite membrane consisting of a thin zeolite film (
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| 14. |
- Aguilar-Mamani, Wilson, et al.
(författare)
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Internal structure of a gel leading to NBA-ZSM-5 single crystals
- 2018
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Ingår i: Journal of porous materials. - : Springer. - 1380-2224 .- 1573-4854. ; 25:6, s. 1551-1559
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Tidskriftsartikel (refereegranskat)abstract
- Porous gel structures are formed during the synthesis of the zeolite ZSM-5 due to the reaction between a source of aluminosilicate, sodium hydroxide, water and a structure directing agent, such as e.g. tetrapropylammonium (TPA) or n-butylamine (NBA). In the present work, the formation of the gel in a heterogeneous system leading to the crystallization of NBA-ZSM-5 zeolite from leached metakaolin was studied extensively. The solid and liquid phases obtained after separation were analyzed by inductively coupled plasma sector field mass spectrometry, dynamic light scattering, extreme high resolution-scanning electron microscopy, energy dispersive spectroscopy, high resolution-transmission electron microscopy, X-ray diffraction and nitrogen gas adsorption. The main gel phase formed after hydrothermal treatment exhibited a sponge-like structure resembling those forming in (Na, TPA)-ZSM-5-based systems. For the first time, the walls of the main gel were shown to be inhomogenous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. The data presented in this paper is of primary importance to understand the mechanism by which the gel is consumed and contributes to the growth process of the zeolite crystals.
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| 15. |
- Aguilar-Mamani, Wilson, et al.
(författare)
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Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment
- 2018
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Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 487, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.
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| 16. |
- Aguilar, Wilson, et al.
(författare)
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Comparison between leached metakaolin and leached diatomaceous earth as raw materials for the synthesis of ZSM-5
- 2014
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Ingår i: SpringerPlus. - : Springer. - 2193-1801. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Inexpensive raw materials have been used to prepare ZSM-5 zeolites with SiO2/Al2O3 molar ratios in the range 20 - 40. Kaolin or Bolivian diatomaceous earth was used as aluminosilicate raw materials and sodium hydroxide and n-butylamine were used as mineralizing agents and template. Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and to reduce the amount of iron and other impurities. After mixing the components and aging, hydrothermal treatment was carried out and the products were recovered The results clearly show for the first time that well-crystallized ZSM-5 can be directly prepared from leached metakaolin or leached diatomaceous earth using sodium hydroxide and n-butylamine as mineralizing agents and template under appropriate synthesis conditions. A longer induction time prior to crystallization was observed for reaction mixtures prepared from leached diatomaceous earth, probably due to slower digestion of the fossilized diatom skeletons as compared with that for microporous leached metakaolin. The use of leached diatomaceous earth allowed higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of Mordenite formed, which was related to the high calcium content of diatomaceous earth. Another considerable advantage of diatomaceous earth over kaolin is that diatomaceous earth does not require heat treatment at high temperature for metakaolinization.
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| 17. |
- Aguilar, Wilson, et al.
(författare)
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Dendritic growth of NBA-ZSM-5
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Ingår i: Microporous and Mesoporous Materials. - 1387-1811 .- 1873-3093.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Crystallization of ZSM-5 zeolite from a gel using n-butylamine as structure-directing agent was studied. Extreme high-resolution transmission and scanning electron microscopy showed the presence of dendritic features that are present at the crystal surface during most of the reaction time that become smoother towards completion of the crystallization. In addition, a web that likely stems from the gel, comprised of alumina-rich nanoparticles between the dendrites at the surface of the crystals was also identified. When the gel is not in direct contact with the crystal surface, dendrites and the web are not observed, and the crystals grow faster. Thus, the alumina-rich web retards the crystal growth and cause the formation of dendritic features.
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| 18. |
- Ahlberg, Sofia, 1984, et al.
(författare)
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Archipelago from file to factory
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Material and Detail is a course that spans from designing a project to producing and building it. Its basis is parametric design, where a shape is changed by changing some of its variables. Being able to control a design parametrically opens possibilities of trying different solutions quickly, allowing the architect to calibrate one that fits the task precisely.The purpose of the course is to investigate new ways of producing architecture and to familiarize the students with the entire file-to-factory process. The starting point of a single material is a way of making the process more easy to focus. What are the specific characteristics for steel, what can only steel do? At the same time, the idea of taking pieces of a material and forming them into a global shape is at the basis of all craft traditions. This makes the pavilion an apt match for the courtyard of Röhsska – museum of design, arts and crafts.
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| 19. |
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| 20. |
- Akhtar, Farid, et al.
(författare)
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Hierarchically porous binder-free silicalite-1 discs : a novel support for all-zeolite membranes
- 2011
-
Ingår i: Journal of Materials Chemistry. - 0959-9428 .- 1364-5501. ; 21:24, s. 8822-8828
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Tidskriftsartikel (refereegranskat)abstract
- Thermal expansion mismatch between the zeolite film and the support is an important cause for the formation of defects and cracks during the fabrication and use of zeolite membranes. We have studied how silicalite-1 discs with a permeability comparable to commercially available alumina supports can be produced by pulsed current processing (PCP) as a novel substrate for all-zeolite membranes. Hierarchically porous and mechanically strong membrane supports where the surface area and crystallography of the silicalite-1 particles were maintained could be obtained by carefully controlling the thermal treatment during PCP consolidation. In situ X-ray diffraction and dilatometry showed that the coefficient of thermal expansion (CTE) of the silicalite-1 substrate was negative in the temperature range 200-800 degrees C while the commonly used alumina substrate displayed a positive CTE. The critical temperature variation, Delta T, and thicknesses for crack-free supported zeolite films with a negative CTE were estimated using a fracture energy model. Zeolite films with a thickness of 1 mu m can only sustain a relatively modest Delta T of 100 degrees when supported onto alumina substrates while the all-zeolite membranes can support temperature variations above 500 degrees
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| 21. |
- Akhtar, Farid, et al.
(författare)
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Hierarchically porous binder-free silicalite-1 discs : a novel support for all-zeolite membranes
- 2011
-
Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 21:24, s. 8822-8828
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Tidskriftsartikel (refereegranskat)abstract
- Thermal expansion mismatch between the zeolite film and the support is an important cause for the formation of defects and cracks during the fabrication and use of zeolite membranes. We have studied how silicalite-1 discs with a permeability comparable to commercially available alumina supports can be produced by pulsed current processing (PCP) as a novel substrate for all-zeolite membranes. Hierarchically porous and mechanically strong membrane supports where the surface area and crystallography of the silicalite-1 particles were maintained could be obtained by carefully controlling the thermal treatment during PCP consolidation. In situ X-ray diffraction and dilatometry showed that the coefficient of thermal expansion (CTE) of the silicalite-1 substrate was negative in the temperature range 200-800 degrees C while the commonly used alumina substrate displayed a positive CTE. The critical temperature variation, Delta T, and thicknesses for crack-free supported zeolite films with a negative CTE were estimated using a fracture energy model. Zeolite films with a thickness of 1 mu m can only sustain a relatively modest Delta T of 100 degrees when supported onto alumina substrates while the all-zeolite membranes can support temperature variations above 500 degrees.
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| 22. |
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| 23. |
- Akhtar, Farid, et al.
(författare)
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Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H-2 separation performance
- 2015
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 493, s. 206-211
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Tidskriftsartikel (refereegranskat)abstract
- Graded silicalite-1 substrates with a high gas permeability and low surface roughness have been produced by pulsed current processing of a thin coating of a submicron silicalite-1 powder onto a powder body of coarser silicalite-1 crystals. Thin zeolite films have been hydrothermally grown onto the graded silicalite-1 support and the all-zeolite membranes display an excellent CO2/H-2 separation factor of 12 at 0 degrees C and a CO2 permeance of 21.3 x 10(-7) mol m(-2) s(-1) Pa-1 for an equimolar CO2/H-2 feed at 505 kPa and 101 kPa helium sweep gas. Thermal cracking estimates based on calculated surface energies and measured thermal expansion coefficients suggest that all-zeolite membranes with a minimal thermal expansion mismatch between the graded substrate and the zeolite film should remain crack-free during thermal cycling and the critical calcination step.
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| 24. |
- Albrecht, Knut, et al.
(författare)
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Immunohistochemical distribution of cyclic nucleotide phosphodiesterase (PDE) isoenzymes in the human vagina: : A potential forensic value?
- 2007
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Ingår i: Journal of forensic and legal medicine. - : Elsevier BV. - 1752-928X. ; 14:5, s. 270-274
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Tidskriftsartikel (refereegranskat)abstract
- Objectives Phosphodiesterase (PDE) isoenzymes are key proteins involved in the maintenance of the normal function of various tissues of the human body including those of the male and female urogenital tract. More recently, PDEs and their main substrates, cyclic GMP and cyclic AMP, have also been assumed to play a crucial role in the control of the human vagina. In order to elucidate the potential significance of phosphodiesterases as marker proteins in female genital organs, it was the aim of the present study to evaluate by means of immunohistochemistry the distribution of cGMP- and cAMP-PDE isoenzymes in specimens of the human vagina. Methods Conventional immunohistochemical techniques (double antibody technique, laser fluorescence microscopy) were applied to sections of the human vaginal wall in order to evaluate the presence of the PDE isoenzymes 1, 2, 3, 4, 5 and 10. Results Immunoreactivities (IR) specific for PDE1 (cAMP/cGMP-PDE, Ca2+/Calmodulin-dependent), PDE2 (cAMP-PDE, cGMP-dependent) and PDE5 (cGMP-PDE) were exclusively registered in the smooth musculature of vaginal arterial vessels, whereas no signals were detected in non-vascular tissue. IR indicating the expression of the cAMP-degrading PDE4 was mainly observed in the vaginal epithelium. Vaginal epithelial cells also presented immunosignals specific for PDE3 (cAMP-PDE, inhibited by cGMP) and PDE10 (dual substrate PDE), nevertheless, these stainings were less abundant than those related to the PDE4. IR for PDE10 was also registered in inflammatory cells located in the subepithelial region of the vaginal wall. Conclusion Our study revealed the presence of IR specific for PDE1, PDE2, PDE4, PDE5 and PDE10 in sections of the human vagina and demonstrated that these enzymes are not evenly distributed in the tissue. Especially, the prominent expression of the cyclic AMP-PDE4A in the vaginal epithelium may give hint to a potential significance of this isoenzyme as a forensic marker protein. The findings give a rationale to investigate further as to whether the immunohistochemical detection of PDE4 may represent a new forensic tool in order to identify human vaginal epithelial cells.
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| 25. |
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