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In this work, a hierarchical Al2O3carbon fiber (H-Al-CF) was successfully fabricated for application in the removal of iodide ions from water. High yields of Al2O3-coated carbon fiber were prepared by a sol–gel process using waste paper fibers as templates and carbon sources. The H-Al-CF is fabricated by an in-situ growth of AlOOH nanocrystals on the surface of carbon fibers following calcination. The synthesized H-Al-CF exhibits the developed porosity including mesopores and macropores, and has high-specific surface area (348.9 m2 g−1) and iodide ions' adsorption efficiency (92.3%). The in-situ growth process ensures that H-Al-CF has a more stable structure, further promoting higher adsorption efficiency. [ABSTRACT FROM PUBLISHER]

A numerical model of a vacuum dewatering process was established with a level-set method to simulate two-phase flow in a two-dimensional paper sheet model with constructed volume forces representing flow resistance in a three-dimensional environment. Nine cases of various volume force representations were investigated by comparing numerical and experimental data. Based on the dry content and dwell time relation, the best model is obtained when accounting for in-plane flow resistance at the paper–wire interface. Compared to the other numerical cases, considering the blockage of the pore space, the top layer of the wire plays an essential role in determining the flow resistance during the vacuum process. To validate the maximum dewatering rate obtained in the model, new experimental data with a higher frequency of sampling are needed. The computational time for the two-phase flow models in this study is extensively reduced due to the removal of the internal structure. This distinction enables time-efficient simulations of the vacuum dewatering process in which several dewatering parameters such as the level of the vacuum, the influence of a moving vacuum pulse, and higher basis weights could be investigated. [ABSTRACT FROM PUBLISHER]

The objective of this work will be to look at basic micro-level simulations of liquid state and movement. Defining liquid movement at fiber-coating boundaries is essential when modeling surface wetting of paper fibers. Drying studies have shown that chemical additives in base paper or coating color may reduce or increase quality, productivity, and energy efficiency considerably. The latest question is, Which are the factors that are significantly influencing liquid movement at fiber-coating boundaries? A phenomenon of less liquid drainage at lower paper moisture content is studied in this work together with the fiber hornification process. Fiber hornification is a complex change in the physicochemical properties of the fiber surface and the state of boundary molecules. Another important objective is to show how hornification may be accounted for in basic calculations. This while, printing properties of paper (mottling, etc.), may then be connected to the formation of the base paper and its drying history, explaining in more detail the importance of microlevel physicochemical property changes at fiber surfaces. [ABSTRACT FROM AUTHOR]

Porous nanocellulose paper was fabricated and applied as a light outcoupling medium. The nanocellulose papers were prepared using cellulose powder and a high-pressure homogenizing process. The translucent nanocellulose paper had high total transmittance and haze, and gave off diffuse light when the incident light passes through it. Through the application of the fabricated nanocellulose paper on the external surfaces of organic light-emitting diode (OLED) devices, it was possible not only to enhance the luminous efficiency but also to widen the angular light distribution. As this paper is intrinsically flexible, it can be applied to various forms of light sources bearing curvature. [ABSTRACT FROM AUTHOR]

The most important issue when coating paper is the modelling of the moisture movement in the coating process, since the water movement pattern is strongly connected to binder movement and the final structure of fibres and coating colour, which in turn affects the final printing properties of the paper. Therefore, we are now studying a novel laboratory method to determine the dynamic water movement in a hygroscopic porous media, i.e. the liquid movement in the paper coating process. The experimentally determined physical properties yield information relevant to the mass and energy balances of a real paper coating process. We have also studied the widely used Lucas-Washburn capillary suction theory in combination with the build-up of a filter-cake in the coating colour. The study shows, that the water loss from the coating colour into a hygroscopic material can be well explained by applying vapour diffusion into the base paper as the governing mass transfer mechanism. [ABSTRACT FROM AUTHOR]

Some new observations concerning the spatial-temporal dynamics of selfaffine interfaces formed in paper-wetting experiments are reported. We find that the motion of the wet front in a porous medium has a stepwise nature. The height of the wetted area, as a function of time, displays a Devil's-staircase-like behaviour with scaling exponent delta, whereas the front width oscillates erratically with time. These erratic oscillations possess a statistical self-affine invariance in time with the scaling exponent chi, which is found to be equal to the growth exponent beta. We also note that the values of chi, beta and delta, as well as the interface roughness (Hurst) exponent H vary from one experiment to another in wide ranges, and that their distributions obey a normal distribution. The mean values of all the exponents are dependent on the paper structure, but not on the environmental conditions. Furthermore, we find that the mean value of beta depends on the interface front orientation with respect to the fibre direction in the paper, whereas the mean values of H and delta do not depend on it. [ABSTRACT FROM AUTHOR]

Part of the dewatering in a paper machine takes place via vacuum suction boxes situated below the moving web. In addition to the removal of liquid water, considerable amounts of air are sucked through the paper. The air flow that accompanies dewatering is a crucial parameter for the electricity consumption of a vacuum system. The present study models this air flow, combining differential conservation equations with fiber characterization. Measured air flow rates for different vacuum levels, basis weights, and pulp types are compared to model predictions. More than 70% of the data agree within the range of experimental error. [ABSTRACT FROM PUBLISHER]

Research in restoration and conservation is directed vs. more sustainable working materials, methods and technologies. Electrophoretic removal, from porous material, of undesired stains due to charged species is theoretically an interesting alternative to chemical cleaning methods, but the lack of specific and comprehensive research work leads to controversial opinions about the efficiency and the needed harmfulness for the treated objects. In this work paper, samples with artificial rust stains were subjected to electrophoretic cleaning treatments in mineral water as electrolyte. Treatments were carried out either in a bath by complete sample immersion between the distanced electrodes or by sample wetting and sandwiching between the electrodes. Evaluation of cleaning efficiency and treatment effects was based on colour change measurements (image analysis of scanned paper samples before and after the treatment and by colorimetric data via spectrophotometric measurements), investigation of morphological changes by SEM observations and folding endurance measurements. [ABSTRACT FROM AUTHOR]

Natural fibers, such as baggase and bamboo were the focus of this work in producing a new high performance paper. In this work, bagasse pith with a porous structure, which is helpful for the attachment of a functional material, was used to produce a high performance composite paper. Powdered bamboo leaf particles were attached as the functional material to the bagasse pith using a variety of conditions involving treatment times, bamboo leaf concentrations and pith length. The smaller particles (less than 45 μm) which were classified by sieve showed a higher degree of attachment than the bamboo leaf particles which were of a size greater than 45 μm. It was found that a degassing process increased the amount of attached bamboo particles, by about 3 times. Moreover decreasing the volume of water necessary for particle flow resulted in a higher adhesion ratio of bamboo particles by about 50%. This was achieved without any chemical processing. Most bamboo particles around the inlet of the pith pores were easily removed on washing. Furthermore, cationization resulted in an improved adhesion ratio and a greater adhesion of the bamboo particles to the pith. [ABSTRACT FROM AUTHOR]

In the above paper five errors have been found. [ABSTRACT FROM AUTHOR]

The plate-type negative electrodes for Li-ion rechargeable battery were prepared by pressure-pulsed chemical vapor infiltration of pyrolytic carbon at 950°C from C 3 H 8 (30%)-H 2 into the TiN-based electroconductive forms having the fibrous structure. The electrodes had the three-dimensional current paths in the layers of active materials without the organic binders and the conductive additives. The charge-discharge profiles were similar to that observed in non-graphitizable carbon having disordered structure. Reversible capacity of pyrolytic carbon at current density of 0.2 mA cm -2 and coulombic efficiency at the first cycle were∼500 mA h g -1 and∼72%, respectively. The capacity at current density of 8 mA cm -2 maintained 80% of that at 0.2 mA cm -2 . [ABSTRACT FROM AUTHOR]

The Journal of the American Institute for Conservation's latest issue features a diverse range of papers and a book review that highlight key themes in the conservation field. Articles cover topics such as systemic racism, preservation of shading papers, analysis of ancient bronze artifacts, and innovative desalination techniques for fragile objects. The collection emphasizes the importance of inclusivity, technical advancement, and cultural preservation in the field of conservation, urging readers to consider the future with both caution and optimism. [Extracted from the article]

The characteristics of ink vehicle absorption into porous structures has formed the basis of a number of recent studies. Kalela, Ridgway and Gane (11th International Printing and Graphic Arts Conference, Bordeaux, 2002) considered an example of common impression cylinder deposits as a result of poor coldset ink adhesion especially in the presence of excess fountain solution. These studies centre on the absorption mechanisms of pigmented coatings and how these can be adjusted to enhance ink-coating adhesion. By developing techniques of tack cycle analysis and correlation with adhesion, i.e. observing print density on the pull-off areas using the ink-surface interaction tester (ISIT), it has been possible to assess ink-coating adhesion. To enhance the adhesion properties of inks, two strategies for coating designs are discussed. The first is to increase the number of ultrafine pores and to increase simultaneously the pigment surface area to enable a capillary-driven separation of oils from solved resins and to provide higher adsorptive power for resins. This was tested by the inclusion of a novel surface-structured calcium carbonate. The second is to introduce an oleophilic species into the coating structure, achieved by the inclusion of hydrophobic talc via a co-structure between talc and hydrophilic dispersed calcium carbonate (Gane, Buri, and Blum, International Symposium on Paper Coating Coverage, Finland 1999). Mercury porosimetry measurements of model coatings using these pigment combinations are used to illustrate their effect on coating structure. These structures are modelled using a computer network simulator, an absorption algorithm is applied to generate the absorption dynamic for each structure. The differences in wetting front are illustrated. It is seen that only at the shortest timescales is there any difference in the absorption dynamic (ignoring any surface chemistry effects). It can therefore be concluded that the observed improvements in this study of ink adhesion are related to adsorptive mechanisms, and absorption rate governs the dwell time over which this adsorption can occur. [ABSTRACT FROM AUTHOR]

A general model for through drying of tissue was developed based on the equations of continuity in combination with correlations for heat and mass transfer. The model incorporates different geometric descriptions together with corresponding heat and mass transfer correlations for flow through cylindrical conduits and flow through packed beds of cylindrical fibers. At low intensities, i.e., at low airflow rates and low drying air temperatures, the model shows very good agreement with experimental data found in the literature and accurately predicts a period of constant drying rate due to saturation of the drying air. However, at higher drying intensities, the model predicts drying rates that are generally higher than what is found in experimental studies described in the literature. The model also predicts a period of constant drying rate that has not been observed in experiments at higher drying intensities. To illustrate the effect of nonuniform pore size distribution on the average drying rate, a model including a variable pore size distribution was developed. The results show that the early onset of the falling rate period in through drying at higher intensities could be explained by channelling effects caused by a nonuniform pore size distribution. [ABSTRACT FROM AUTHOR]

Drying of moist porous media, such as food or pulp and paper, is an energy-intensive process. Traditional drying technologies have disadvantages, including high energy consumption, thermal degradation of the samples, as well as high capital cost. In this work, a new technology, making use of the Dielectrophoresis (DEP) mechanism, is introduced, to enhance the drying process of a moist porous medium. DEP is a translational motion of neutral matter caused by polarization effects in a non-uniform electric field. In a typical drying process, due to the existence of an electric permittivity gradient between liquid and vapor interfaces, the DEP force can act as an external force to effectively extract the vapor phase away from the product. This in turn enhances the evaporation rate. This article experimentally investigates the influence of the DEP force on the drying of moist hand-sheet paper samples. Specifically, the temperature profile and sample weight are monitored under various applied electric potentials. The non-uniform electric field is generated from a unique electrode design. The experimental results show a significant impact of the DEP force on the temperature profile and drying rate. In addition, the results also show extremely low energy consumption and high energy efficiency associated with the application of the DEP force for drying. With the application of the electric field, up to 10 °C drop in surface temperature and a 33.6% reduction in drying time have been achieved. The experimental work provides a basic understanding of this novel technology that could enhance the drying process in various industry sectors such as forest products, foods, pharmaceuticals, and chemicals. [ABSTRACT FROM AUTHOR]

Absorption of fluids into porous media controls the printability characteristics of coated papers in respect to ink setting rate and phenomena such as wicking and bleeding. The dynamic of absorption is related to the runnability on printing presses. Pore structure, size distribution, and surface chemistry are the parameters which can be used to design structures for optimal absorption. To achieve a working understanding it has been necessary to develop the theory of absorption to encompass the short timescale fast absorption occurring during wetting of the fluid ink onto the surface of the paper. The phenomena of fluid spread and absorption are studied and shown to depend on the observed pore size distribution rather than porosity alone. This finding calls into question the traditional acceptance of the Lucas–Washburn relationship for such porous networks as the hydraulic absorption radius determined from experimental absorption rate measurements fails to follow the actual measured pore size trend. It is necessary to invoke the concept of a preferred pathway of absorption in which only selected groups within the finest connecting pores or throats of the network in combination with intermediate pore reservoirs contribute maximally to the transmission of fluid through the coating structure as porosity increases. By defining the pore size range involved in this mechanism using an inertial wetting term, found in the short time solution to the Bosanquet equation, it is possible for the first time to identify the connective structures responsible for the important time dependent absorption properties of coatings and their relationship to the ink tackification and/or setting rates for a range of printing ink solvents and diluents, including offset, rotogravure, flexographic, and ink jet inks. Additionally, the differential chromatographic effect of coatings and associated binder systems results in further time dependent offset ink setting phenomena in which miscible ink oils of different natures separate within the coating pores and between the pores and synthetic latex binders. In situ determination of the viscosity and solids content of an offset ink via static ink tack measurements allows the dynamic of ink setting to be studied on real coating systems. Combining these criteria, the necessary steps can be followed to design the coating pigment structures required for optimising existing and future fluid-based printing technologies. [ABSTRACT FROM AUTHOR]

Shale is a complex porous medium with multi-scale pores and well-developed fracture networks. This paper aims to use modeling and numerical simulation methods to study the transport of shale gas in a complex multi-scale matrix-fracture system. In this study, mathematical modeling and programming was used to establish digital models of shale gas multi-scale matrix and 3D discrete fracture network. Based on the transport mechanisms of shale gas, this study derives the mathematical models of shale gas transport in different transport media, and uses the finite element method to solve and analysis the transport of shale gas in the multi-scale matrix-fracture system. The model is verified by real shale gas field data. The results show that the fractal dimension of organic pores have great effects on shale gas transport. When the fractal dimension is greater than 1.4, the increase on gas production is particularly obvious. Compared with organic pores, the effect of fractal dimension of inorganic pores is smaller. The existence of the fracture network has an effect of up to 25% on gas production, and the optimal fracture density is 200. [ABSTRACT FROM AUTHOR]

Food safety issue is becoming an international challenge for human health owing to the presence of contaminants. In this context, reliable, rapid, and sensitive detecting technology is extremely demanded to establish food safety assurance systems. MOFs (Metal-organic frameworks) are a new type of porous crystalline material with particular physical and chemical characteristics presented in food safety requirements. (Bio)sensors driven MOF materials have emerged as a promising alternative and complementary analytical techniques, owing to their great specific area, high porosity, and uniform and fine-tunable pore buildings. Nevertheless, the insufficient stability and electrical conductivity of classical MOFs limit their utilization. Employing graphene-derived nanomaterials with high functional elements as patterns for the MOF materials not only improves the structural instability and poor conductivity but also impedes the restacking and aggregation between graphene layers, thus significantly extending the MOFs application. A review of MOFs-graphene-based material used in food contamination detection is urgently needed for encouraging the advance of this field. Herein, this paper systematically outlines current breakthroughs in MOF-graphene-based nanoprobes, outlines their principles, and illustrates their employments in identifying mycotoxins, heavy metal ions, pathogens, antibiotics, and pesticides, referring to their multiplexing and sensitivity ability. The challenges and limitations of applying MOF-graphene composite for precise and efficient assessment of food were also debated. This paper would maybe offer some inspired concepts for an upcoming study on MOF-based composites in the food security context. [ABSTRACT FROM AUTHOR]

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The growth, reproduction, and metabolic activities of microorganisms can lead to blockages within porous media, a phenomenon commonly observed in landfill engineering. Termed as microbial plugging, this phenomenon is significantly influenced by the inherent permeability characteristics of the system. In this study, we propose a simulation model based on the Monod equation to elucidate the clogging process caused by microorganisms in one-dimensional pore channels. Our primary focus is on the application of this model in landfill bioreactor systems. We demonstrate that microbial clogging in these systems is predominantly affected by factors such as the maximum environmental carrying capacity and pore size. These factors are directly influenced by the presence of solid waste within the landfill. By offering a theoretical foundation for mitigating microbial clogging in pore channels of landfill bioreactor systems, this research has the potential to contribute to the development of more efficient and effective waste management practices. Implications: Microbial plugging is a hot research topic in the field of environmental geotechnical engineering. Previous papers often only considered the reduction of pore volumes, while neglecting the role of clogging and the uneven distribution of permeability. In this paper, we established a permeability model for porous media that considers microbial growth and plugging. This model can reflect the temporal variation of permeability with microbial growth and predict the spatial distribution of permeability. This paper can promote on the utilization of microbial plugging technology in landfills or solid waste. [ABSTRACT FROM AUTHOR]

Silicon has the advantages of high specific capacity (4200 mAh/g), low lithium potential and abundant reserves, and is considered to be one of the most suitable materials for replacing graphite negative electrode. However, the commercial silicon particle size is too large to be used directly as an electrode material, and the silicon material will undergo huge volume expansion during the lithium insertion process, resulting in the fragmentation of the active substance falling off from the fluid collector, resulting in a sharp decline in battery capacity. This defect seriously affects the commercial application of silicon-based anode materials. In this paper, a kind of silicon anode material with porous structure is designed for the defect of silicon anode material. The aluminum-silicon alloy prepared by atomization method presents a three-dimensional porous spherical structure after etching, and the abundant holes reserve space for the volume expansion during the process of lithium silicon embedding and improve the transmission rate of lithium ions. It was found that when the silicon content was 12%, the reversible specific capacity of the material was 1269 mAh/g at 4000 mA/g current density, and the capacity retention rate of 100 cycles relative to the fourth cycle was 59.5%. Compared with ball-ground silicon, the capacity retention rate is increased by 25.7%. Therefore, this paper provides a new idea for the design of porous silicon-based anode materials. [ABSTRACT FROM AUTHOR]

Stress sensitivity and dynamic relative permeability are undeniable phenomenon in oil reservoir numerical simulation. In this paper, a complex two-phase flow model was established considering the deformation of porous media and relative permeability dynamic changes during water injection. A sensitivity analysis on this new model is carried out. The results reveal that stress sensitivity is a key factor that cannot be ignored when using reservoir numerical simulation to calculate water saturation. When the stress-sensitivity coefficient is not considered, the average water saturation of the model is 51.59%. When the stress-sensitivity coefficient is 0.12MPa−1, the average water saturation of the model is 48.45%. After considering stress sensitivity, the average water saturation of the model decreases by 6.1%. The water saturation difference between the new model and the traditional model is mainly reflected in the vicinity of the water injection well. Additionally, the influence of the range of changes in reservoir permeability on the calculation of water saturation by the new model cannot be ignored. [ABSTRACT FROM AUTHOR]

In this study, a porous silicon anode material was designed to solve the problems of electrode deformation and electrical contact loss caused by volume expansion during the use of silicon anode material. Silicon-aluminum composite powder prepared by high-energy ball milling method, after Al is removed by chemical etching, Si particles show larger specific surface and porosity, and the larger pores provide a certain buffer space for the volume expansion of silicon during lithium intercalation, which can better release stress during the volume expansion, so that it has better cycle performance and higher capacity retention rate. The results showed that the porous Si anode was prepared by ball milling Si-Al powder for 12 h, and the first charge specific capacity was 2912.9 mAh/g at 200 mAh/g current density, and the coulombic efficiency was 83.91%. After 100 cycles at 400 mA/g current density, the capacity retention rate was 34.6% compared with the fourth cycle. This paper provides a new idea for the industrialization of porous silicon. [ABSTRACT FROM AUTHOR]

We discuss in this paper the chemical reaction impacts on complimentary convectively flow of the gelatinous secondary graded fluid past a countless vertical porous plate underneath the effects of uniform transversal magnetic field. Time reliant penetrability as well as fluctuating suction are also explored. The prevailing equations are resolved with the regular perturbation method for the small amplitudes of the permeability. The solutions for the velocities, temperature as well as concentrations have been obtained computationally; in addition, behaviour is also explored. The skin fiction, the Nusselts number as well as Sherwood numbers are also found in addition to those behaviour computationally conferred. It is concluded that the velocity is reduced with enhancement in the intensity of the magnetic field and Prandtl number whereas it is enhanced by the ever-increasing thermal Grashofs number. The magnitude of the temperature of the flow field diminished with increase in the Prandtl number, heat source parameter. The concentration of the flow field is reduced by a rise into the Schmidt number and chemical reaction parameters. [ABSTRACT FROM AUTHOR]

An expanding sheet problem is more relevant when the thickness of the sheet is variable and it bears frequent applications in polymer press, paper production, metallic plate cooling, etc. On the other hand, activation energy is an important phenomenon of chemical reaction in flow dynamics of Newtonian and non-Newtonian fluids. The activation energy and chemical reaction have vital applications in food preparing, the mechanism of water and oil emulsions, chemical engineering, and more. So in this project, the impacts of activation energy and binary chemical reaction on MHD two-dimensional boundary layer flow of Williamson nanofluid on an expanding surface of variable thickness embedded in Darcy–Forchheimer porous medium are investigated. Using suitable transformations, the governing equations are transformed into a set of non-linear ordinary differential equations (ODEs). Later, numerical solutions have been achieved by well-known MATLAB inbuilt function 'bvp4c'. Several vital results are explored for variations of involved physical parameters and those are presented in graphical and tabular modes. The achieved results suggest that when wall thickness parameter increases, there is a contrast in behaviors of velocity, temperature and nanoparticle concentration if there is a condition that the shape parameter is greater than or less than unity. For the former case, the above flow properties reduce with wall thickness parameter, whereas, for the latter case, those are showing significant growth. The Brownian motion of nanoparticles causes an increase in temperature and a reduction in nanoparticle concentration, whereas due to thermophoretic force, both temperature and nanoparticle concentration rise. Due to the presence of activation energy in chemical reaction, the nanoparticle concentration enhances, while, temperature decreases(increases) near(away from) the sheet. With increasing reaction rate parameters, nanoparticle concentration diminishes, but temperature increases near the sheet. The surface drag force decreases with Williamson fluid parameter, while it increases with the magnetic parameter, inverse Darcy number, and Forchheimer parameter. On the other hand, the surface heat flux and surface mass flux are decreasing functions of Williamson fluid parameter, magnetic parameter, inverse Darcy number, and Forchheimer parameter. It also reveals that surface heat flux reduces with increasing reaction rate parameters, whereas surface mass flux increases. Finally, for the growth of activation energy parameter, initially surface heat flux rises and surface mass flux declines, but for its larger values, the quantities turn out to be constants. Also, the surface heat and mass fluxes are decreasing functions of thermophoresis parameter. [ABSTRACT FROM AUTHOR]

Recently, it has been proposed to develop space power systems based on filtration combustion of metal powders with oxygen supplied by a chemical oxygen generator. The experiments with lithium and magnesium powders at natural infiltration of oxygen have shown propagation of both counterflow and coflow combustion waves. However, natural filtration combustion of metal powders at relatively low pressures is not sufficiently understood. In the present paper, we investigate the natural coflow combustion waves propagating through a porous medium. The porous matrix is made of metal particles that react with oxygen flowing from the open end of the sample to the reaction zone where it is consumed forming a condensed product which also has a porous structure. The gas flow is due to the pressure difference between the pressure at the open end and that in the reaction zone (the so-called natural filtration). The open end is where the sample is ignited, so that the gas flows through the reaction products, i.e. in the same direction as the combustion wave propagates (coflow filtration). Our mathematical model involves the conservation of energy equation and gas mass, solid reactant mass, and gas momentum balances, as well as an equation of state, and appropriate boundary and initial conditions. It is studied analytically under the combustion front approximation. When the reaction zone is close to the open end, there is sufficient amount of oxygen in the reaction zone and the reaction is controlled by kinetic factors (the kinetic regime of propagation). As the reaction moves away from the open end, it is gas supply that becomes a limiting factor (filtration regime). Both kinetic and filtration regimes of propagation as well the transition between them are analytically studied in this paper. [ABSTRACT FROM AUTHOR]

An experimental method using a novel design to characterize the air flow and water removal during vacuum dewatering in paper manufacturing is discussed. The experimental setup involves the intermittent application of vacuum, similar to commercial systems, using a rotating disk with slot opening arrangement. The system is capable of commercially realistic residence times of the order of milliseconds. The intermittent application of vacuum simulates vacuum dewatering on commercial paper machines. The air flow rate is calculated from changes in pressure and temperature in the vacuum tank underneath the sample. The role and importance of air flow during vacuum dewatering is studied by accurately measuring the air flow, properly taking into account the leaks during vacuum dewatering. The method described here provides for the first time accurate air flow and water removal data during vacuum dewatering. Methods of analysis of the experimental data are also presented. This information can be used to better understand the water removal process as well the role and importance of air flow during vacuum dewatering. [ABSTRACT FROM AUTHOR]

The coupled thermal-hydro-mechanical (THM) analysis of saturated porous media is of great significance and has been widely used in various engineering fields. However, the classical Biot theory assumes that the physical parameters of porous media are constant and ignores the influence of pore size on wave propagation characteristics, which cannot reflect the actual situation. Based on the nonlocal theory and Biot wave equation, a nonlocal coupled Biot THM dynamic model for porous media with variable physical properties is established by introducing the temperature-dependent factor function. Utilizing the nonlocal coupled Biot THM theory, the dynamic response of forced convection in a half-space saturated porous media under surface harmonic thermal action is investigated in this paper. The analytical solutions of temperature increment, displacement, stress, and pore water pressure of saturated porous media are obtained by means of differential operator decomposition. In addition, the effects of the temperature-dependent factor and porosity on the nonlocal model at different frequencies, and the effects of the nonlocal parameter on the distribution rules of various physical fields at different frequencies are explored in depth. [ABSTRACT FROM AUTHOR]

Annually, a tremendous amount of mercury is emitted due to anthropogenic activities. As a consequence, occupational and environmental exposure to mercury has drawn broad concern all over the world, and attempts have been sustained to progress analytical methods. The main limitation in exposure assessment is the complexity of biological and environmental samples. Environmental and biological samples need sample preparation to eliminate matrix interferences as well as pre-concentration of the ultra-trace analyte. Among sample preparation methods, considerable attention is devoted to solid-phase extraction (SPE). Porous materials play a vital role in the solid phase extraction procedure for the adsorption and desorption of the target analytes. In this paper, porous materials that were applied for inorganic mercury solid phase extraction were reviewed from 2009 until 2023. Through this study, porous materials were classified and the extraction parameters of each analytical method, including the type of solid phase extraction, porous adsorbent, adsorbent amount, extraction efficiency, real matrices, and detection technique, were clarified. Ultimately, novel attitudes toward green analytical chemistry and innovative ideas were discussed in order to open new horizons. [ABSTRACT FROM AUTHOR]

The present paper deals with propagation of plane harmonic waves in nonlocal visco-thermoelastic porous medium based on the nonlocal strain gradient theory. For the first time, the assumptions of Green-Naghdi model type III of hyperbolic thermoelasticity with voids in conjunction with nonlocal strain gradient theory are taken into account in formulation of the problem. The constitutive relations and field equations for nonlocal thermoelastic materials with voids are presented. In addition to transverse waves, three longitudinal waves (elastic, thermal, volume fraction) can be observed. The fundamental solution to equations for steady oscillations is derived. The effects of nonlocal length scale parameter, voids, viscosity on phase velocities, attenuation coefficients and penetration depths of waves with diverse frequencies are comprehensively studied and graphically presented. [ABSTRACT FROM AUTHOR]

Porous ceramics find extensive applications in aerospace and other fields, and the measurement of their electromagnetic parameters is helpful in optimization of material properties and device designs. In this paper, a free-space 8f quasi-optical measurement system consisting of a vector network analyzer, a 325–500 GHz frequency expansion module, and four off-axis parabolic mirrors have been established to measure the transmission parameter S21 of porous ceramics. The complex permittivity was extracted according to the Newton-Raphson iterative method utilizing its measured S21 parameters based on flat mode. The porous ceramics with different porosity and density were measured and the relationships between their permittivity and porosity and density was established, respectively. These results are beneficial to the quality evaluation and application design of porous ceramic materials in the aerospace field. [ABSTRACT FROM AUTHOR]

This paper proposes a novel concept and methodology to study longitudinal wave propagation in entangled metallic wire material (EMWM), a porous structural network consisting of spatial helix wires. The numerical model of EMWM is constructed using representative volume elements (RVE) obtained through X-ray tomography and skeletonization of a standard specimen. By increasing the approximate periodic boundary, the improved wave and finite ele-ment method (WFE) is employed to model EMWM as approximately periodic structures, allowing for numerical simulations of wave propagation characteristics. Frequency bands and resonance modes of EMWM are calculated to analyze the characteristics of one-dimensional wave propagation. The numerical results show that EMWM exhibits unique frequency band characteristics compared to typical periodic porous materials. In the frequency range of 15 to n n 35 kHz, the first pass band corresponds to the tensile-compressive motion of the entire specimen, while the higher pass bands correspond to localized vibrations within the spatial wires. Additionally, the frequency bands can be adjusted across a wide range based on the relative density of EMWM specimens. The improved WFE method and obtained numerical data can facilitate the application of EMWM on high frequency vibration isolation. [ABSTRACT FROM AUTHOR]

This paper presents an overview of recent developments in experimental investigation and numerical modeling of highly porous cement-based materials, focusing on traditional Portland cement (PC) and geopolymer foam concrete. It starts by introducing the advantages of using highly porous cement-based materials compared to their dense counterparts and then delves into the properties of PC and geopolymer foam concrete. The first part of the review is dedicated to the experimental investigation, including mixture proportions, foaming methods, mechanical properties and air-void systems. This part also summarizes and discusses various strength prediction models for foam concrete that were drawn from experimental data. The second part of the review is dedicated to the computational methods used to simulate porous materials, and attention is focused on continuum-based and discrete-based approaches. Finally, the failure mechanism of porous cement-based materials is discussed, along with comparing the failure criteria for both dense and porous cement-based materials. [ABSTRACT FROM AUTHOR]

This paper investigates the acoustic performance of a double-wall system with a porous layer and presents a global sensitivity analysis of sound attenuation. The transfer matrix method is first applied to predict sound transmission through the structure. This method offers a relatively simple and cost-effective way to model the complex acoustic interactions in these systems and provides rich high-frequency information. The method represents sound wave propagation for each layer using a transfer matrix that depends on the thickness and physical characteristics of each material, and interface matrices are introduced to consider boundary conditions between adjacent layers. The poroelastic layer is modeled using the Biot-Allard approach with nine parameters. Then a global sensitivity analysis is performed using Morris and Sobol methods to identify the parameters that have a significant impact on sound transmission loss. The Morris method is used first to eliminate the parameters that have the least impact, and the Sobol method is then employed to analyze the remaining parameters and their interactions in more detail. The study focuses on eleven parameters, including all the physical parameters of the foam, and thicknesses of plates, cavity, and foam. The results of the sensitivity analysis indicate that geometrical parameters such as the thickness of different layers have the most significant impact on the sound transmission loss response in the lower frequency range. In contrast, foam properties such as flow resistivity have more influence in the higher frequency range. Overall, this study is the first to apply sensitivity analysis methods to the problem of sound transmission through double wall systems with porous layers, providing valuable insights into the system's behavior and its design optimization. [ABSTRACT FROM AUTHOR]

In the existing paper, thermo-mechanical buckling performance of three-layered advanced fluid-infiltrated porous shells that are embedded between two GPLs-reinforced composite layers is investigated. The influence of the fluids in the pores is investigated using Skempton coefficient. Imperfection types and ratio effects are also considered. Moreover, for the face layers, Graphene nanoplatelets (GPLs) weight fraction and dispersion patterns are studied. After deriving the governing equations employing virtual displacement method, they are solved analytically via Navier's approach. Finally, the impact of different factors on the critical buckling loads (CBLs) and temperatures (CBTs) of cylindrical, spherical, and doubly-curved shells is assessed. [ABSTRACT FROM AUTHOR]

In recent years, the application of porous materials in practical engineering has become increasingly common. Under extreme thermal conditions, how to accurately describe the heat conduction and structural response of porous materials is a key issue in the structural safety and functional design of porous materials. Among them, it is particularly important to consider the size-dependent and memory-dependent effects for small-sized structures or microdevices of porous materials. To address these issues of porous structures and to guide their applications as well as optimization, this paper first investigates the thermoelastic transient response of porous microplates subjected to thermal and stress shocks at the left boundary based on the Atangana-Baleanu (AB) fractional-order generalized thermoelastic theory by considering nonlocal effects and fractional-order strain, which is combined with the thermoelasticity theory of porous materials and the dual-phase-lag (DPL) heat conduction model. The governing equations are then established and solved using the Laplace transform and its numerical inversion. Finally, the effects of newly defined fractional order parameters, nonlocal parameters and the initial magnitude of the mechanical shock on the dimensionless temperature, volume fraction field, displacement and stress distribution are discussed and displayed graphically. [ABSTRACT FROM AUTHOR]

In this paper, the effect of flexible and rigid porous wall on the detonation propagation velocity in hydrogen-oxygen mixtures is investigated systematically. The roles of hydrogen concentration, initial pressure, porous wall geometry and porosity are considered in detail. Pressure sensors are used to record the time-of-arrival of the detonation wave, and the average velocity of the detonation wave can be obtained. The results indicate that the detonation propagation limit in a tube filled with porous materials is shorter than the value obtained in a smooth tube, and the velocity deficits increase obviously with the increase of the porosity and thickness. In the detonation limit, the velocity of detonation wave decreases firstly and then rises after passing through the absorption wall, which is due to the reflection of the shock wave on the surface of the wall. The reaction rate is increased quickly by introducing the local disturbance in the reaction zone, compensating the adverse effects of the porous wall. Compared with changing porosity, increasing thickness has a more significant effect on detonation attenuation. This phenomenon can be due to the excessive bending of the wave front and the heat loss increases. [ABSTRACT FROM AUTHOR]

In order to provide a reliable tool for thermal-hydraulic simulation of pebble bed high temperature gas-cooled reactors (HTGRs), a two-dimensional model was developed based on the porous media model and user-defined scalar (UDS) function of FLUENT software. Then, the model was applied to the numerical simulation of the shutdown test of the 10 MW high temperature gas-cooled test reactor (HTR-10) at 9 MW power level, and the temperature distribution and flow field distribution in the reactor were obtained and compared with the results of the experimental data. The reliability of the model in this paper was verified. Based on the model, the effects of the water-cooled panel temperature and the initial core temperature on the thermal-hydraulic characteristics of HTR-10 after shutdown were further explored. The results show that there is a decoupling phenomenon between the residual heat transfer within the core and the heat dissipation of the pressure vessel. The initial core temperature has relatively little effect on the heat dissipation and maximum temperature of the pressure vessel, but it has a significant impact on the thermal characteristics of the core area. [ABSTRACT FROM AUTHOR]

In this article, a simultaneous initial inverse problem and parameter estimation inverse problem in context of the vacuum paper drying process is presented. In this problem an evaporation constant and initial distribution of the water content are retrieved indirectly based on the temperature measurements at selected sampling points during vacuum phase of the process. As such, a problem is ill-posed and two different Tikhonov-type regularization techniques are proposed. The L-curve method was used to establish the value of the regularization parameter for both techniques. Results obtained with both regularization techniques are compared. [ABSTRACT FROM AUTHOR]

After being injected into the porous media, the dispersion system of preformed particle gel (PPG) tends to enter high permeability regions and block water channeling passages, which forces the subsequent water to turn to the low permeability regions and thus increases sweep efficiency and enhances oil recovery. However, it is still unclear about the influence factors and the mechanisms how PPG increases water flow resistance, which limits the application of PPG in more oilfields. Therefore, the paper combines the lattice Boltzmann method (LBM), the discrete element method (DEM) and the improved immersed moving boundary (IMB) method to simulate the migration of deformable PPG in porous media. On the basis, the paper quantitatively analyzes the variation law of displacement pressure across the porous media and discusses the influence factors such as the PPG diameter, elasticity modulus and the number concentration. Results indicate that, because of the friction and retention of PPG in pore-throat, the displacement pressure across the porous media during PPG flooding is much higher than that during water flooding. In other words, the existence of PPG increases the flow resistance of injected water. Besides, the displacement pressure is always fluctuant resulting from the continuous process of PPG migration, retention, deformation and remigration. Influence factor analysis shows that the incremental value and fluctuation degree of flow resistance increase with the PPG diameter, elasticity modulus and the number concentration. The study not only provides useful reference for future PPG flooding, but also benefits the development of deformable particle flow theory. [ABSTRACT FROM AUTHOR]

This is part II of a study reported earlier on a method to characterize the air flow and water removal characteristics during vacuum dewatering. This article presents experimental data and analysis of results from the use of a cyclically actuated vacuum dewatering device for removing moisture from wetted porous materials such as paper with the intermittent application of vacuum and accompanying air flow though the material. Results presented include sheet moisture content as a function of residence time and hence water removal rate under a variety of process conditions. Also, experimental results on air flow through the wet porous structure and hence the role and importance of air flow during vacuum dewatering are presented. Vacuum dewatering process conditions include exit solids content between 11 and 20% solid under applied vacuum conditions of 13.5 to 67.7 kPa (4 to 20 in. Hg). Regression analysis indicated that the exit sheet moisture content exhibited a nonlinear relationship with residence time with exit solids reaching a plateau after a certain residence time. Final moisture content correlated linearly with the average overall flow rate of air through the paper sample and the basis weight of the material. [ABSTRACT FROM AUTHOR]

To improve the explosion suppression efficiency of porous media in natural gas hydrogen-doped pipelines, this paper designs and builds an experimental platform with dimensions of 10 cm × 10 cm × 100 cm organ transparent glass explosion pipeline and researches the synergistic effect of the use of nickel foam and CO2 to inhibit the explosion of hydrogen-doped methane with a hydrogen doping ratio of φ = 10%. Studies have shown that using a dual explosion suppression mechanism, the synergistic effect of nickel foam and CO2 acting at different jet positions has a significant inhibitory effect on the flame and overpressure of low-hydrogen-ratio methane explosions. The synergistic CO2 in porous media has a more potent inhibitory effect on the right-side wall jet than on the left-side and left-side jet. When the synergistic impact of nickel foam and CO2 acts on the right-side wall jet, the flame is quenched, substantially attenuating the overpressure peak. When the nickel foam synergistic CO2 acts on the right-side wall jet, the optimal effect is achieved when the CO2 jet pressure is set at 0.3 MPa, which successfully quenches the flame and significantly reduces the overpressure peak. However, the dual explosion suppression mechanism fails when the CO2 jet pressure is 0.2 MPa. [ABSTRACT FROM AUTHOR]

We demonstrate in this paper a super-hydrophilic and oleophobic green porous photothermal material based on wood fiber as a novel oil-repellent photothermal material for efficient solar vapor generation (WF-SP). WF-SP is an excellent light-absorbing material with the advantages of a porous nanostructure, super-hydrophilic, low thermal conductivity, high-temperature resistance, and oleophobicity. Based on these advantages, WF-SP exhibits good solar photothermal conversion performance with solar vapor generation efficiencies of 85.4%, 75.3%, and 70.2% at 1 kW m−2, 2 kW m−2, and 3 kW m−2 radiation intensities, respectively. The results provide new possibilities for the design and preparation of low-cost, green, and pollution-free photothermal materials with high solar thermal conversion efficiency for solar photothermal conversion vapor generation. [ABSTRACT FROM AUTHOR]

Microporous organic polymers (MOPs) are a new type of porous materials, which have advantages of synthetic diversity, chemical and physical stability, microporous size controllability, etc. MOPs indicate broad applications in various fields such as heterogeneous catalysis, gas adsorption, separation, and storage. In recent years, MOPs have attracted an enormous attention in greenhouse gas capture due to their great potential in physisorptive gas storage. Carbazole and its derivatives have been studied extensively as Metal-Organic Polyhedra (MOPs) building blocks due to their unique structural features and versatile functionalization possibilities. This paper systematically reviews the synthesis, characterization and application of carbazole-based polymers, and relationship of structures and properties of these polymers. The application of the polymers in carbon dioxide (CO2) capture field is analysed taking advantage of their adjustable microporous structure and electron rich properties. This review also provides novel insights regarding functional polymer materials that have high ability of greenhouse gas capture and absorbing selectivity will be obtained by reasonable molecular design and efficient synthesis. [ABSTRACT FROM AUTHOR]

In this paper, the high flux tubes of 25 mm outer diameter with the content of 8% and 12% nanoparticles were experimentally studied with the refrigerant R141b under atmospheric pressure. The liquid mass flux was controlled from 128.30 to 252.03 kg/m2·s, the maximum heat flux provided by the electric heating rod was 80 kW/m2, and the range of the superheated degree was from −7 to 4 °C. The results indicate that the porous media promotes the phase change at a low superheated degree, and the heat transfer capacity is 1.88 times that of the smooth tube. Additionally, the vapor quality increases significantly with the increase of nanoparticle concentration. Moreover, the heat transfer coefficient decreases as the outer wall temperature increases due to the formation of the gas film but increases with the increase of nano-powder content. Under the same superheated degree condition, the maximum heat transfer coefficient of the sintered porous tube with 12% nano-powder content is 1.3 times that of the tube with 8% nano-powder content. [ABSTRACT FROM AUTHOR]

Gabion weir comprises porous materials packed with distinct shapes and sizes of gravel. The gabion weir is eco-friendlier than an impervious weir, as its opening enables water life and sediment materials to pass through it. Aeration is how natural processes or physical structures enhance the contact area and time between water and estranged air. This process improves the dissolved oxygen (D.O.) of water. The D.O. is one of the best determinants used for water quality measurement. This paper investigates the prediction of mass oxygen transfer over the gabion weir by ensemble models. The outputs of gabion weir oxygen mass transfer were estimated using bagging, boosting, and stacking by taking input parameters such as average size, porosity, the gabion weir height, discharge per unit width, and drop height. The dataset was taken by conducting experiments. By comparing these modeling ensembles, it was found that random forest-based bagging outperformed all proposed models. Nevertheless, all applied ensemble models were performing well, but published traditional equations were performing incredibly poorly. As sensitivity analysis suggests, the discharge per unit width was the most sensitive input. An uncertainty study was also carried out. [ABSTRACT FROM AUTHOR]

Maintaining a moist wound environment facilitates the wound healing process. However, traditional dressings such as medical gauze are difficult to meet this condition and easy to cause wound infection when the gauze is replaced. In this paper, a novel multifunctional medical dressing based on keratin porous materials was prepared by the freeze-drying method. Keratin was first modified by poly (ethylene glycol) dimethacrylate (PEGDMA) to increase its hydrophilicity. Then, the carboxymethyl chitosan (CMCS) was mixed with keratin solution to further improve the pore-forming properties, and finally, the solution was dried through the freezing method to obtain the porous dressing. The performance of the dressing was detailed and studied using DPPH free radical scavenging ability, water retention, blood coagulation, and bacteriostasis tests. The results showed that PEGDMA grafting greatly improved moisture retention from 22 to 43. CMCS blending not only improved the uniform and compact of the pore structure, but also effectively improved blood coagulation and antibacterial properties. After blending with CMCS, the performance of the keratin porous material was greatly improved. Carboxymethyl chitosan is positively charged, which makes the negatively charged platelets easy to aggregate, so the coagulation performance is greatly improved, and the BCI decreased to 15%. At the same time, the antibacterial performance against Staphylococcus aureus was greatly improved, and the optimal condition was PEG-g-KR:CMCS = 6:4. The PEG-g-KR/CMCS dressing prepared in this method had the characteristics of promoting wound healing, good moisture absorption and water retention, excellent blood coagulation performance and strong bacteriostasis. It is of great significance to the research and application of composite dressings. [ABSTRACT FROM AUTHOR]

This paper aims to establish a general stability result for a one-dimensional linear swelling porous-elastic system with infinite memory, irrespective of the wave speeds of the system. The proof is based on the multiplier method and some properties of convex functions. The kernel in our memory term is more general and of a broader class. Our output extends and improves some of the available results on swelling porous media in the literature. [ABSTRACT FROM AUTHOR]

Tight oil is an unconventional petroleum resource, which occupies a essential position in the global energy structure. The main purpose of this paper is to quantitatively characterize the lower limit of the physical properties of tight oil reservoirs in nanomaterial porous media. This paper starts with the single-phase deionized water flow experiment in micro-nano-quartz tube, combined with the tight oil reservoir core single-phase simulation, formation water seepage experiment, analyzes and characterizes the low-velocity and nonlinear seepage characteristics of tight reservoir fluid. At the same time, combined with the dynamic network simulation technology, the process of water flooding in tight oil reservoirs under different conditions is simulated, and the influence of each influencing factor on the two-phase seepage of water flooding is determined. In addition, combined with different water injection capillary numbers, water flooding nuclear magnetic resonance experiments, the dynamic characteristics and distribution changes of oil and water, in two phases in the water flooding process are analyzed, and the simulation results are used for verification and analysis, to indicate the reasonable and efficient water flooding development of tight oil reservoirs. [ABSTRACT FROM AUTHOR]

Multizone hydraulic fracture (HF) helps to enhance the commercial production rate of oil and gas in unconventional reservoirs. However, the efficiency of multizone HF highly depends on the cluster/perforation spacing and in situ stress field. Therefore, this paper investigates the phase field characteristic during multizone HF under different perforation spacing and in situ stress field. The total stress tensor involves the influence of initial stress while the fracture growth is characterised by the evolution equation of phase field. In addition, the numerical simulation is verified by a rectangular domain subjected to internal fluid injection. Then, the hydraulic fracture patterns from a group of pre-existing notches subjected to an identical fluid injection rate are examined. The numerical results show that the hydraulic fractures in multizone HF are the automatic product of the evolution equation of phase field without requiring any external fracture criteria. A diverted fracture scenario is shown in most cases and the fracture growth is inhibited if the stress perpendicular to the perforations increases. The fluid pressure in the fracture and the breakdown pressure increases with the increase in the notch spacing and the stress perpendicular to the perforations. The fluid pressure in the middle notch is larger than that in the upper notch. Reversion of the in situ principal stress direction greatly inhibits the growth of multizone hydraulic fractures, which causes the failure of multizone HF. The numerical investigations in this paper can provide a new perspective for multizone HF design. [ABSTRACT FROM AUTHOR]