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AbstractIn this study, we developed a transient convective heat and mass transfer model of an acoustically levitated slurry droplet evaporating in an atmosphere of air, water vapor, and soluble gas. The advanced model considers the effects of acoustic streaming, forced convection, non-isothermal gas absorption, and adsorption of dissolved gas on the evaporation rate of a liquid droplet containing small active solid particles. Adsorption of dissolved in a droplet soluble gas by solid particles leads to decreased dissolved gas concentration in a liquid droplet. A reduction in dissolved gas concentration in a liquid droplet causes an increase in the mass flux of active soluble gas from a gaseous phase to a slurry droplet, which causes a rise in the heating effect of absorption and an increase in evaporation rate of a droplet. The heat effect of adsorption also intensifies the evaporation rate. It is shown that the time of porous shell formation is essentially shorter when solid particles in slurry droplets are active compared to inert particles. [ABSTRACT FROM AUTHOR]

The Ru atomic catalyst-doped GaN (Ru-GaN) model was established by density functional theory (DFT), and the adsorption models of transformer oil dissolved gas (CO, H2, CH4, C2H2, C2H4 and C2H6) by a Ru-GaN monolayer were optimised. From the adsorption energy, differential charge density, electron state density, molecular orbital and desorption properties, the modification mechanism of Ru-GaN and the gas-sensitive response mechanism of Ru-GaN to CO, H2, CH4, C2H2, C2H4 and C2H6 were systematically studied. The introduction of metal Ru increases the defect state of GaN to provide the active site for the adsorption of gas molecules and reduces the adsorption barrier of GaN to gas molecules. The results show that Ru metal-doped GaN can adsorb CO, C2H2 and C2H4 by chemisorption, with Eads of −2.068 eV, −2.422 eV and −1.877 eV and Qt of −0.1696 e, −0.0671 e, −0.1222 e. In addition, charge redistribution leads to changes in the density of states, molecular orbitals and the conductivity of CO, C2H2 and C2H4 adsorption systems, indicating excellent gas sensitivity to the three gases. The desorption time further verified that Ru-GaN is an ideal CO and C2H2 gas scavenger and a recyclable material for C2H4 gas sensors. [ABSTRACT FROM AUTHOR]

Developed a bilayered nanofibrous membrane, aimed to achieve a new class of air filtering media that can capture particulate matter, microbes and can also adsorb the harmful toxic gaseous components like formaldehyde (primary indoor pollutant). A layer of oriented nanofibers prepared via coaxial electrospinning with poly(m-phenylene isophthalamide) as core, polyacrylonitrile/polyethylenimine blended polymer as shell and another layer of randomly aligned nanofibers (polyacrylonitrile-silver nanoparticle nanofibers produced using single-nozzle electrospinning) were put together, to provide stable porous structure and induce multilevel filtration. The successful synthesis of this robust coaxial-based nanofibrous filter medium would not only make it a promising candidate for air filtration, but it will provide a new insight into designing and fabricating composite coaxial nanofiber-based membranes by incorporating various functional materials into shell for toxic gas adsorption related applications and the core can be of a mechanically robust material to address the easily collapsing cavity structure of nanofibers. The results revealed that the developed filter with superior mechanical property (11.88 MPa by virtue of poly(m-phenylene isophthalamide) fiber macromolecule that existed as rigid skeletal structure) can provide high removal efficiencies of 99.23% toward particulate matter, 99.6% toward bacterial aerosols, adsorb formaldehyde an indoor toxic gaseous pollutant and have potential antimicrobial effects against Escherichia coli and Bacillus subtilis while maintaining low pressure drop of 53.03 MPa, which to the best of our knowledge, has never been accomplished with a single filter medium before. [ABSTRACT FROM AUTHOR]

CO2 enhanced shale gas recovery has the merits of both increasing the natural gas production to address the global energy crisis as well as simultaneously the geological storage of CO2 to reduce the anthropogenic greenhouse gas emissions. Although it has huge development potential and wide application prospects, this technology is still in a very preliminary stage of deployment. The research status of the CO2 enhanced shale gas recovery is summarized in this paper in order to stimulate further research and development in this field worldwide to address the dual problem of energy crisis and environmental degradation. [ABSTRACT FROM AUTHOR]

Two metal coordination polymers, namely {[Co(MIBA)2]·2H2O}n (SNUT-3) and {[Cu(MIBA)2]·2H2O}n (SNUT-4), where HMIBA = 4-(1H-2-methylimidazol-1-yl)benzoic acid, were prepared by hydrothermal methods. Single-crystal X-ray analysis revealed that the structure of SNUT-3 exhibits a 3D→3D fourfold interpenetrating structure with diamondoid frameworks, while SNUT-4 shows a 2D + 2D → 3D inclined polycatenation structure. The gas adsorption property of SNUT-3 and photocatalytic activity of SNUT-4 for the degradation of Rhodamine B has been explored. [ABSTRACT FROM AUTHOR]

Gas adsorption properties of key natural fibres were investigated through monitoring the adsorption process of ammonia onto wool and cotton by time-resolved infrared spectroscopy. It was found that Langmuir isotherm model best described ammonia adsorption onto wool and cotton, indicating monolayer adsorption. The adsorption capacity of wool and cotton for ammonia was found to be 7.948 × 10−5 mol g−1 and 3.066 × 10−5 mol g−1, respectively. Adsorption diffusion was found to be the rate limiting step for wool in the initial adsorption stage, following the Dumwald–Wagner model. For cotton, adsorption reaction process was found to be the rate limiting step for the whole adsorption, following the pseudo-second-order model. The activation energy values of ammonia adsorption were calculated to be 26.50 kJ mol−1 for wool and 30.43 kJ mol−1 for cotton, which demonstrates that ammonia adsorption onto fibres requires energy. The study could promote developing textile products for odour control. [ABSTRACT FROM AUTHOR]

First-principles calculations based on spin-polarised density functional theory have been used here to investigate the structural, electronic and magnetic properties of tape-heme monolayer (THM) with gas molecules (H2O, N2, HCN, NH3, NO2 and SO2) adsorption. Our results suggest that H2O and NH3 are physisorbed on THM while N2, HCN, NO2 and SO2 are adsorbed on THM by chemisorption. The toxic HCN, NH3, NO2 and SO2 can be effectively captured by THM according to their adsorption energy (> 0.50 eV). The adsorption of NO2 (or SO2) can partly (or completely) decrease the spin moment of THM and induce the transition from the metallic property into half-metallic (or semiconductor) behaviour. The magnetism of the NO2 adsorption system is sensitive to tensile strain while that of the SO2 adsorption system is invariably non-spin polarised regardless of the compressive or tensile strain. The electronic structure of the NO2 and SO2 adsorption system can be effectively modulated by external biaxial strain. Our findings reveal that THM could effectively detect toxic NO2 and SO2 in an environment with high sensitivity and selectivity and reactivity, indicating that it possesses a potential application in the field of heme-based gas sensors. [ABSTRACT FROM AUTHOR]

Iron-based catalysts can be used as de-NOx catalysts due to their good adsorption performance to gas molecules. However, the adsorption behaviours of NH3, NO, and O2 molecules on ferrous oxide surface are unclear. In this paper, the adsorption properties of NH3, NO, and O2 molecules over FeO (100) surface and oxygen-defected FeO (100) surface were studied by a density functional theory calculation. The Fe-top of the FeO (100) surface is the most active site. NH3 and NO can be adsorbed on the Fe-top sites by N terminal. The adsorption of O2 on the Hollow site of the FeO (100) surface has a larger adsorption energy. When oxygen-defected presents on the FeO (100) surface, the adsorption performances of NH3 and NO on the Fe-top sites are slightly decreased. NO and O2 can be adsorbed on the O-defected site, in which the adsorption energy of O2 is larger. For the adsorption of double molecules, O2 + NH3 or O2 + NO adsorbed on the FeO (100) surface have synergistic effects, respectively, which enhance the adsorption performance. Moreover, the co-adsorption behaviours of O2 + NH3 and O2 + NO on the O-defected FeO (100) surface also occur. [ABSTRACT FROM AUTHOR]

In this study, we designed an experimental system of surface potential during coal adsorption of gas to examine the characteristics of surface potential in this process. The results suggested that surface potential was generated in this process and that it was enhanced with the passage of time. In adsorption cycles, the higher the pressure, the greater the surface potential signals, and they increase exponentially. Thereby, research on surface potential during gas adsorption on coal holds great theoretical significance for understanding the physical properties of coal. [ABSTRACT FROM AUTHOR]

Alumina–zirconia (Al2O3–ZrO2) composite was prepared by combustion method and used to remove Congo red and Methylene blue from aqueous solutions. It was characterized using SEM–EDS, XRD and gas adsorption techniques. The results obtained from gas adsorption and SEM agree with each other, showing meso- and macro-porosity of inter-agglomerate pores. The removal of the two dyes was pH dependent, acidic pH favoured Congo red removal, while basic pH favoured Methylene blue. The, mechanism of adsorption was not limited to electrostatic attraction between the adsorbent and the dye molecules. Adsorption kinetic of both dyes was consistent with Pseudo-second-order model. The data obtained fitted to Langmuir and Liu isotherm models, with the maximum adsorption capacity of 57. 50 and 53.44 mg g–1 for Congo red and Methylene blue, respectively. The thermodynamic parameters indicated that the adsorption is spontaneous and exothermic. The mechanism of adsorption was elucidated using XRD and FTIR techniques. [ABSTRACT FROM AUTHOR]

Nitrogen (N2) and carbon dioxide (CO2) gases injection yield substantially various recovery ways. Here, a one-dimensional mathematical model is applied comprising of mass balances for explaining gas sorption and flow, and a geomechanical relationship to describe the permeability changes during gas injection. That's why numerical simulations for investigating the performance of injecting flue gas mixture in enhanced coal bed methane (ECBM) recovery are represented. Significant intuitive features are found regarding the gas flow dynamics at the time of displacement and influences of sorption on ECBM operation. The study revealed that the injection of pure CO2 causes much reduction in cleat permeability, but pure N2 is injected to increase the permeability without any loss of injectivity. Therefore, pure CO2 causes more efficient displacement in terms of total CH4 recovery, while the addition of N2 to the mixture assists to make quicker the initial methane recovery. [ABSTRACT FROM AUTHOR]

Recently, coalbed methane (CBM) has become one of the major unconventional gas resources in the world. In 2017, the US CBM proved reserves were estimated at 336 Billion Cubic Meter (BCM) while the production was about 27 BCM. Coal formations possess unique characteristics that necessitate accurate characterization and fundamental understanding of the prevailing mechanisms. For instance, gas sorption processes in CBM require a comprehensive characterization integrating sorption factors such as the pressure, temperature, moisture content, ash content, and gas adsorption capacities. In addition, the uncanny gas diffusion behavior in CBM formations poses a challenge for accurate gas diffusion quantification accounting for the unusual varying nature of the gas diffusion coefficient with pressure and temperature. Besides, the stress-sensitivity nature of the CBM permeability still represents an active research area where experimental measurements are needed to develop relationships for the modeling studies. Additionally, CBM reserve estimates are highly dependent on the in-place gas contents. Therefore, one needs to consider not only the adsorbed gas content, but also the free and soluble gas contents – particularly in lower rank CBM reservoirs. Consequently, it is challenging to predict the fluid behavior in CBM formations given the uniqueness and complexity of the governing mechanisms. In this review, we are providing both an overview of the CBM’s fundamental and the recent research studies that revolve around the major aspects of CBM’s characterization and modeling. [ABSTRACT FROM AUTHOR]

The pore size distribution of four shale samples were characterized by and compared between CO2 adsorption, N2 adsorption, MIP and NMR. The results show that CO2 adsorption has an absolute advantage for characterization of pores smaller than 2 nm. N2 adsorption is reliable for 2–50 nm pore characterization and is superior to NMR in the 2–10 nm range. NMR has advantages for 10–100 nm pore characterization, and MIP has advantages for characterization of pores larger than 100 nm. NMR offers the widest range of observations, and order of the maximum resolution of these methods is CO2 adsorption > N2 adsorption > NMR > MIP. [ABSTRACT FROM AUTHOR]

We report a wide Q-range neutron diffraction study on the absorption of oxygen molecules into deuterated ZIF-8 as the system is taken through its gate-opening transition by applying gas pressure at 85 K. The combination of the quantitative nature of the total neutron scattering technique and the modelling performed using the Empirical Potential Structure Refinement (EPSR) technique has allowed us to determine the behaviour of the absorbed fluid upon condensation within the pores with unprecedented detail. The results show that the number of oxygen molecules found inside the central core of the spherical pore of the sodalite cage does not vary as the gate-opening transition is induced. After going through the structural transition, there is a rearrangement of the molecules and the extra molecules entering the structure are instead pushed towards the window apertures in the open structure. These results help to provide a greater insight into the nature of the structural flexibility of ZIF-8 and to understand its gas sorption behaviour. [ABSTRACT FROM AUTHOR]

H2S and CO2 are acid contaminants of natural gas and biogas, which removal have been studied using adsorption data for monocomponent and binary mixtures. However, equilibrium adsorption data for H2S + CO2 + CH4 mixture has not been investigated yet. In this work, H2S and CO2 partition coefficients (K) and activated carbon (AC) selectivity (S) for H2S + CO2 + CH4 mixture separation at high-pressure and different temperatures were determined. To reach this goal, monocomponent isotherms for H2S, CO2 and CH4 on Brazilian babassu coconut hush AC were experimentally determined at different temperatures and pressures. Then, obtained data were correlated by Langmuir and Tóth models, and multicomponent adsorption was predicted using Extended Langmuir, Extended Tóth and Ideal Adsorption Solution Theory (IAST) methods. Results indicate AC captures approximately 26 wt% of H2S or CO2. K values for CO2 and H2S reached more than 3 and 26, respectively, depending on the predictive model utilized and were higher for diluted mixtures (high CH4 content in gas phase). S values for CO2 and H2S can reach values greater than 25 for Tóth + IAST. Furthermore, selectivity toward H2S is approximately 5.6 times greater than CO2. The effect of temperature on multicomponent results indicate K and S values decrease as temperature increases. Therefore, results obtained herein show that is possible to separate H2S and CO2 from mixture containing CH4 using this AC as adsorbent and better separation performance was observed for low H2S and CO2 concentrations and lower temperatures. [ABSTRACT FROM AUTHOR]

Porous organic cages are a class of adsorbents that have shown promise for a variety of applications. The octahedral cyclohexane-functionalised imine-based cage, commonly referred to as CC3, is perhaps most recognisable in this regard. However, most gas adsorption studies concerning this cage have focused on chromatographic or noble gas separations. Here, we examine this cage for the adsorptive separation of a wide variety of small molecules, including acetylene, ethylene, ethane, methane, and others. The internal surface of the cage is an optimal binding environment for gaseous substrates and as such the material displays adsorption enthalpies of −15 to −35 kJ/mol, depending on adsorbate. These values are particularly high for an adsorbent lacking coordinatively unsaturated metal sites and are likely a result of optimal cage geometry, which can be inferred from its isostructural nature to one of the pores in a well-known metal-organic framework, HKUST-1. Given this and the soluble nature of this cage, we additionally report optimisation of the high-pressure methane storage properties of this cage by tuning its density. [ABSTRACT FROM AUTHOR]

To evaluate pore networks of the lower Cambrian Niutitang Shale in the Cen-gong Block, multiple techniques, including geochemical analysis, low-pressure gas (CO2 and N2) adsorption, mercury intrusion capillary porosimetry (MICP) and field-emission scanning electron microscope (FE-SEM), were performed to investigate pore structure, including pore-size distribution (PSD), pore volume and surface area of black organic-rich shales from two wells to better understand the mechanism of shale-gas accumulation. Geochemical analysis shows that equivalent vitrinite reflectance ranges from 2.1 to 3.5% and are overmature. Surface areas and pore volumes of micropores calculated from CO2 adsorption, which vary from 8.23 to 37.39 m2/g and from 3.06  10−3 to 10.89  10−3 cm3/g, respectively, can provide large amounts of adsorptive sites for shale-gas accumulation. N2 adsorption shows reversed S-shaped isotherms, which are classified into type H2 and H3 hysteresis loops, indicative of ink-bottle pores and slit-or plate-like pores. N2 adsorption and MICP analysis indicates that the inorganic-associated pores in shales may play a significant role in the storage and production of hydrocarbons. High-resolution FE-SEM analysis suggests that OM pores (OMPs) are common in Niutitang samples with a dominant diameter less 50 nm, but a sample with the highest total organic carbon (TOC) of 10.01 wt% has few OMPs, whereas a sample with the TOC of 7.51 wt% has more OMPs. The percentage of OMP area vs total organic matter area (Øs) ranges from 1.70 to 7.92%. The pore structure characteristics of TX1 well, calculated by multiple techniques, are better than samples from TM1 well. In addition, pore types are dominated by interparticle, intraparticle and organic matter pores, and the minor amounts of OMPs in TM1 well indicates that most of the organic matter may have lost the potential to generate hydrocarbons owing to the release of formation pressure with some graphitisation and high-angle fractures larger in the TX1 well. TOC content, mineral composition and tectonically related thermal maturity may be the main controlling factors of the pore structure and the lower Cambrian Niutitang Shale demonstrates the greatest potential for shale-gas production in South China. [ABSTRACT FROM AUTHOR]

In this study, the CO2adsorption analysis in cellulose acetate–TiO2- and cellulose acetate–3-aminopropyl-trimethoxysilane TiO2-blended membranes was performed. The membranes were also characterized using scanning electron microscopy and Fourier transform infrared analysis techniques. The adsorption results indicated that 120 and 90°C were considered as optimized temperatures for regeneration of cellulose acetate–TiO2and cellulose acetate–3-aminopropyl-trimethoxysilane-modified TiO2membranes. The testing results revealed that adsorption capacity reached maximum at 3.0 bars. Validation of experimental results was performed by pseudo-first-order, second-order and intraparticle diffusion models. The correlation factorR2represented that the second-order model was fitted well with the experimental data. The intraparticle diffusion model represented that adsorption is not a single-step process. [ABSTRACT FROM PUBLISHER]

Presented here is a new Zn(II) compound, namely [Zn4(btec)2(DMA)3]n(1 represents this compound, H4btec = 1,2,4,5-benzenetetracarboxylic acid, DMA = N,N′-dimethylacetamide). This compound crystallizes in orthorhombicPbca space group witha= 19.053(2) Å,b= 18.8010(6) Å,c= 22.9434(8) Å, α = β = γ = 90°, andZ= 8. Single crystal X-ray diffraction analysis reveals that compound 1 features a three-dimensional (3D) framework based on two different dinuclear [Zn2(COO)3] subunits. In addition, the solid-state luminescent property of 1 and the gas sorption properties of the desolvated 1a were also investigated. [ABSTRACT FROM AUTHOR]

Two 3-D MOFs, {[Co2(oba)2(bmip)]·DMA}n(1) and [Cd(1,3-bdc)(bmip)]n(2), where H2oba = 4,4′-oxybis(benzoic acid), 1,3-bdc = isophthalic acid and bmip = 1,3-bis(2-methylimidazolyl)propane, were synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, powder XRD, FT-IR, TGA, and elemental analysis. Complex1features a 3-D→3-D twofold interpenetrating framework, and topological analysis shows the framework can be described as a 6-connected uninodalpcunet having the point symbol (412.63). Complex2shows a 3-D→3-D threefold interpenetrating network that can be described as a 4-connected uninodalcdsnet with (65.8) topology. Gas adsorptions of1were carried out, and photoluminescent properties of1and2were also investigated at room temperature. [ABSTRACT FROM PUBLISHER]

Based on the first-principles of density-functional theory (DFT), the effects of gas adsorption on the change in adsorptive configurations, electronic structures and magnetic properties of graphene with magnetic metal atoms (MMA = Fe, Co, Ni and Mo) systems were investigated. Four metal atoms are strongly trapped at single vacancy graphene (MMA/SV-graphene) and can effectively regulate the adsorption of CO and O2molecules. It is found that the positive charged of MMA are more prone to adsorb the O2than that of CO molecule, and these gas molecules on MMA/SV-graphene induce a different type of magnetic properties of systems. Hence, the differences in electronic and magnetic properties of MMA/SV-graphene with the gas molecules are expected to design graphene-based gas sensors and spintronic device. [ABSTRACT FROM PUBLISHER]

Metal nanoparticles supported montmorillonite with innovative characteristics has led to a new generation of heterogeneous "nanocatalyst." Such catalysts are superior to the conventional catalysts because of several factors like: higher surface area; higher activity; higher selectivity and longer life and thus, developing a newer type of sustainable environmentally friendly catalysts. Metal clay supported nanocatalysts may find a wide range of applications in the area of fine and bulk chemical industries, pharmaceuticals, fuel cell, petroleum refineries, environmental catalysis, and many other fields. This article summarizes the recent advances in the synthesis and characterization of metal nanoparticles supported on modified montmorillonite and their catalytic applications for fine chemicals synthesis. [ABSTRACT FROM AUTHOR]

A detailed force field analysis for polymers of intrinsic microporosity (PIMs) was carried out in this study. The generalised amber force field (GAFF) with united atom transferable potential for phase equilibria (TraPPE-UA), and the atomistic polymer consistent force field were evaluated. Analysis carried out with PIM-1 showed that the use of GAFF for bonded interactions and TraPPE-UA for non-bonded interactions yielded a simulated sample that compared best with available experimental data (wide-angle X-ray scattering and nitrogen adsorption at 77 K). In addition, Brunauer–Emmett–Teller surface areas, calculated from simulated nitrogen isotherms as pseudo-experimental data, showed that this common method failed to measure the geometric surface area of this type of material. These findings are expected to facilitate the predictive screening of different PIM functionalities. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were conducted for a cubic Cu cluster supported on a graphite bilayer. The Sutten–Chen and Lennard–Jones potentials were used for metal–metal and metal–graphite interactions, respectively. Heating and cooling processes were performed by NVT simulations at different temperatures in the range 200 to 1800 K. The melting point was identified on the basis of caloric and heat capacity curves. The calculated melting point was 770 K, far below the bulk melting point of crystalline copper. Several phenomena such as the appearance of a hysteresis (irreversibility) in caloric curves, surface melting, and cluster-induced surface wetting were justified from the results. The simulation of cluster in the presence of gas atmosphere showed that the CO gas is adsorbed more than H2 and it has a greater impact on the cluster's structure. [ABSTRACT FROM AUTHOR]

Adsorption plays an important role in carbon dioxide sequestration and methane recovery processes in deep coal seams. If the effects of coal physical properties on its gas adsorption capacity are considered, it increases with vitrinite content and pressure and reduces with liptinite, mineral matter, moisture contents, and temperature and follows a U-shaped variation with carbon content. Furthermore, CO2 has higher adsorption capacity compared to other gases. There are two main methods to estimate the amount of gas adsorbed in a coal seam, which are called direct and indirect methods. The latter method is more common for coal. In the direct method, the volume of gas released from a coal mass into a sealed desorption canister is measured, and under the indirect method, adsorption isotherms and empirical relations are used. However, any of those methods are unable to count the effect of swelling-induced strain and, therefore, fail in measuring the absolute adsorption in coal. Moreover, among various adsorption models, Langmuir and Dubnin-Radushkevich (D-R) equations are the most widely using models. However, since gas can be absorbed through both adsorption and absorption processes for coal, it is important to have an additional term to count the missing absorption mechanism in both the Langmuir and D-R models. Finally, a new descriptive model for gas adsorption capacity of coal as a function of effective factors is proposed. The new model is based on the existing D-R equation, which was modified by inserting a new expression for the term of micropore capacity. Two types (CO2 and N2) of gas adsorption data for coal from five different locations (British Colombia and Alberta in Canada and Victoria, Sydney and Bowen in Australia) at three different temperatures (273, 296.5, and 318 K) were considered for the model development. According to the model results, new gas adsorption equations can fairly well accurately predict the adsorption capacity in coal. [ABSTRACT FROM PUBLISHER]

To obtain new information about destabilization of wood microstructure caused by drying, effects of drying history on physical properties of wood were studied using the measurements of dynamic viscoelastic properties and gas adsorption. First, dynamic viscoelastic properties of dry wood in the radial direction were measured between 100°C and 200°C. Unstable states of dry wood still existed after heating at 105°C for 30 min and were modified by activated molecular motion in the first heating process to higher temperatures above 105°C, and dry wood subjected to higher temperatures showed larger dynamic elastic modulus (E') and smaller loss tangent (tan δ). The phenomena thought to be caused by the unstable states reappeared after wetting and drying again. Secondly, carbon dioxide adsorptions onto dry wood at ice-water temperature (273 K) were measured, and micropore size distributions were obtained using the Horvath-Kawazoe (HK) method. Micropores smaller than 0.6 nm exist in dry wood. They decreased with elevating drying temperatures from 50°C to 160°C and increased again after rewetting and drying. In conclusion, it was confirmed that wood components in the microstructures were destabilized by drying and that physical properties of dry wood changed with drying histories. [ABSTRACT FROM AUTHOR]

Several methods have been developed and applied in recent years in the characterization of the structure of microporous materials, in general, and of pillared clays, in particular. In the present article, the latest results obtained in the control of the microstructure developed in alumina-pillared clays and various approaches used to the evaluation of the porosity of these materials are reviewed. These include the control of the microstructure developed in pillared clays by adjusting the several parameters involved in the synthesis process, and the evaluation of the porosity of pillared clays. Emphasis is given to the methods to evaluate the pore size and pore size distribution (PSD) of these materials. Two separate sections are devoted to review mathematical modeling studies and 129Xe NMR spectroscopy of physisorbed Xe to investigate the microporous structural properties of these materials. [ABSTRACT FROM AUTHOR]

Gas desorption in vacuum from electron irradiated ultra high molecular weight polyethylene (PE) is measured with a high sensible mass quadrupole spectrometer. Measurements are performed in thick PE irradiated with 5 MeV electron beams at doses of the order of tens of kGy. The irradiation modifies the PE molecules producing dehydrogenation, emission of different Cx-Hy groups, C-enrichment and carbon cross-linking processes. Results indicate that the radiation damage depends on the dose and that a significant change of chemical and physical polymer properties is reached for a critical dose of 18 kGy. [ABSTRACT FROM AUTHOR]

Adsorption isotherms of H 2 and CH 4 on activated carbon fibers (ACF) and single-walled carbon nanohorns (SWNH) were measured at vapor and supercritical conditions. H 2 and CH 4 are adsorbed sufficiently on micropores of ACF and SWNH at the vapor conditions and their adsorption isotherms were described by the Dubinin-Radushkevich equation. This shows clearly that even adsorption of H 2 and CH 4 vapors can be described by micropore filling mechanism. However, the adsorption isotherms of supercritical H 2 and CH 4 sensitively depend on the measuring temperature; the higher the measuring temperature, the smaller the amount of adsorption. Although H 2 adsorption isotherm of SWNH at 77 K is of type I and the maximum surface excess adsorption is 0.7 wt.% at 5 MPa, the adsorption isotherm was of Henry type at 300 K and the adsorption amount is less than 0.1 wt.% at 5 MPa. [ABSTRACT FROM AUTHOR]