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Purpose: The purpose of this paper is to predict a suitable paper substrate which has high capillary pressure with the tendency of subsequent fluid wrenching in onward direction for the fabrication of microfluidics device application. Design/methodology/approach: The experiment has been done on the WhatmanTM grade 1, WhatmanTM chromatography and nitrocellulose paper samples which are made by GE Healthcare Life Sciences. The structural characterization of paper samples for surface properties has been done by scanning electron microscope and ImageJ software. Identification of functional groups on the surface of samples has been done by Fourier transform infrared analysis. A finite elemental analysis has also been performed by using the "Multiphase Flow in Porous Media" module of the COMSOL Multiphysics tool which combines Darcy's law and Phase Transport in Porous Media interface. Findings: Experimentally, it has been concluded that the paper substrate for flexible microfluidic device application must have large number of internal (intra- and interfiber) pores with fewer void spaces (external pores) that have high capillary pressure to propel the fluid in onward direction with narrow paper fiber channel. Originality/value: Surface structure has a dynamic impact in paper substrate utilization in multiple applications such as paper manufacturing, printing process and microfluidics applications. [ABSTRACT FROM AUTHOR]

The urgent need for sustainable waste management strategies has led to the exploration of innovative approaches for the valorization of waste. In this study, a method is proposed for carbonizing waste biomass materials, particularly paper mill waste sludges (primary and biological) and knots, to produce porous carbonaceous supports. Through an initial hydrothermal carbonization followed by carbonization with nitrogen flow, porous carbon materials are successfully generated. The findings of this investigation validate the successful generation of effective carbonaceous supports utilizing waste biomass materials. These materials are then evaluated for their effectiveness as porous supports in the ionic liquid‐catalyzed cycloaddition reaction of CO2 to styrene oxide, achieving a remarkable conversion rate of up to 98% and an impressive selectivity exceeding 99%. Additionally, the results underscore the significant impact of the selected IL on the overall conversion process. Overall, this study presents a promising pathway for the valorization of paper mill waste sludge through the production of porous carbon materials with potential applications in catalysis and beyond. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (microPADs) are emerging as simple-to-use, low-cost point-of-care testing platforms. Such devices are mostly fabricated at present by creating hydrophobic barriers using wax or photoresist patterning on porous paper sheets. Even though devices fabricated using these methods are used and tested with a wide variety of analytes, still they pose many serious practical limitations for low-cost automated mass fabrication for their widespread applicability. We present an affordable and simple two-step process – cut and heat (CH-microPADs) – for the selective fabrication of hydrophilic channels and reservoirs on a wide variety of porous media such as tissue/printing/filter paper and cloth types, such as cotton and polyester, by a lamination process. The technique presents many advantages as compared to existing commonly used methods. The devices possess excellent mechanical strength against bending, folding and twisting, making them virtually unbreakable. They are structurally flexible and show good chemical resistance to various solvents, acids and bases, presenting widespread applicability in areas such as clinical diagnostics, biological sensing applications, food processing, and the chemical industry. Fabricated paper media 96 well-plate CH-microPAD configurations were tested for cell culture applications using mice embryonic fibroblasts and detection of proteins and enzymes using ELISA. With a simple two-step process and minimal human intervention, the technique presents a promising step towards mass fabrication of inexpensive disposable diagnostic devices for both resource-limited and developed regions. [ABSTRACT FROM AUTHOR]

Laha et al. studied the diffusive behavior of a whole-blood drop on filter paper using the generalized capillary bundle model. However, some model parameters should be further refined to accurately reflect the physics involved in this diffusion process. Moreover, citations are missing for some key equations. Addressing these aspects will improve the model applicability to this application and benefit readers in accessing more accurate and detailed information. [ABSTRACT FROM AUTHOR]

Water release is a crucial aspect when considering cleaning effects on water-sensitive materials. In conservation practice, a water-based cleaning method which limits water release is very often needed. Unfortunately, this is not accompanied by an appropriate measure of the effectively released water. In this paper, water release has been measured by comparing traditional cleaning formulations, such as paper pulp and sepiolite, with several gar gel formulations, used by both Italian and European conservators. The assessment has been carried out by the gravimetric method, using three different stone material specimens as reference: Noto calcarenite, Manciano sandstone and Black Bergamo limestone, whose porosity values and distributions are known. Moreover, water distribution has been evaluated by portable NMR tests. Different commercial agar gel products (Bresciani, CTS, Sigma), having different concentrations (3, 4, and 5%), application modes (rigid at room T or fluid warm gels, with and without inserting Japanese tissue paper), and geometry (horizontal in gravity force direction or vertical), have been compared to obtain a full scenario among different water release mechanisms present in real conservation works. The paper faces the important issue of preparing reproducible chemical or water pads as well, useful for further research aimed at comparing cleaning effects in heritage conservation. The most interesting quantitative results can be summarized as follows. The water release measured from paper pulp and sepiolite was found to be 2 to 4 times higher than from any tested agar gel. Water release decreases by increasing agar concentration; an increase in the agar concentration by 1% induces a decrease in water release in the range 16.98–66.88 g depending on the stone; the increase from 4% to 5% is more obvious with respect to that from 3% to 4%. It is possible to assess the effect of the presence of Japanese paper, which is able to reduce the water release from 18 to 76%, depending on the stone and on the agar used. The gravimetric results were also used in the preliminary calibration tests of a contact probe named System Unit Salinity Index (SUSI), recently patented and useful in providing humidity and salinity indexes in a given porous material. [ABSTRACT FROM AUTHOR]

This article explores the use of cellulose and paper-based products in building acoustics. It examines various materials such as cellulose wool, paperboard, corrugated cardboard, and honeycomb panels, and evaluates their acoustic absorption and insulation properties. The results indicate that these paper-based products can be effective alternatives to traditional materials in terms of both absorption and insulation performance. The article emphasizes the potential of paper-based materials in reducing the environmental impact of the building industry. The text also discusses the resonance frequencies and properties of Helmholtz resonators and double walls with the insertion of Helmholtz resonators, providing equations and formulas to calculate their resonance frequencies and transmission loss. It describes the measurement methods used to assess the sound absorption and sound reduction properties of various materials, including cellulose and paper-based products, and presents the results obtained from these measurements. The document also discusses the dynamic properties of paperboard and the testing methods used to measure these properties, as well as the results of tests conducted on cellulose wool. It highlights the environmental benefits of using recycled materials like cellulose wool. The text provides data and analysis on the acoustic properties of various cellulose and paper-based materials used in building construction, including cellulose wool, paperboard, corrugated cardboard, and honeycomb panels. The measurements include parameters such as sound reduction index, sound absorption coefficient, and dynamic Young's modulus. The results demonstrate that these materials have different acoustic characteristics and can be utilized for sound insulation and absorption in [Extracted from the article]

• Richard's equation can be extended to Bingham fluids using the concept of effective viscosity combined with the bundle-of-tube model. • Yield stress has a retarding effect on imbibition, but it can extend the quasi-steady regime on the test line for fan-shaped configuration. • The limiting value for stain growth of sessile droplets of blood in filter papers can be partly attributed to the blood's yield stress and partly to its viscoelasticity. The classic Richards equation is a good model for predicting imbibition of viscous fluids in porous materials such as dry soils or filter papers. It cannot, in principle, be used for physiological fluids such as blood simply because such fluids often exhibit a variety of non-Newtonian behavior such as a yield stress. In the present work, we have theoretically extended the classic Richards equation to viscoplastic fluids obeying the Bingham model using the concept of the effective viscosity together with the bundle-of-tube model. The new imbibition model could partly resolve the discrepancy reported in the literature between the predictions of the classic Richards equation for the stain growth of sessile blood droplets in a typical filter paper. A better fit, however, requires considering other non-Newtonian effects of the blood such as its viscoelasticity. Using the Bingham-modified Richards equation, it is demonstrated that yield stress in a test fluid has a retarding effect on the imbibition phenomenon, so that such fluids may not necessarily reach the test line of a paper-based diagnostic kit. But yield stress is predicted to extend the duration of the quasi-steady regime on the test line of diagnostic kits, which is a desirable effect. The results suggest that inducing (or elevating) the level of yield stress in a test liquid such as blood can be used as a passive means to control imbibition characteristics in paper-based systems. [ABSTRACT FROM AUTHOR]

A wide range of applications are possible with paper-based analytical devices, which are low priced, easy to fabricate and operate, and require no specialized equipment. Paper-based microfluidics offers the design of miniaturized POC devices to be applied in the health, environment, food, and energy sector employing the ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment free and Deliverable to end users) principle of WHO. Therefore, this field is growing very rapidly and ample research is being done. This review focuses on fabrication and detection techniques reported to date. Additionally, this review emphasises on the application of this technology in the area of medical diagnosis, energy generation, environmental monitoring, and food quality control. This review also presents the theoretical analysis of fluid flow in porous media for the efficient handling and control of fluids. The limitations of PAD have also been discussed with an emphasis to concern on the transformation of such devices from laboratory to the consumer. [ABSTRACT FROM AUTHOR]

In the decarbonized society based on the renewable sources, the carbon fiber papers (CFPs) are regarded as key porous materials for the electrochemical energy conversion and storage devices. Searching the optimum microstructure of assembled carbon fiber paper under compression is one of the central challenges in this uprising technology. Herein, we present a tomography-based analytical approach to correlate CFP microstructures and transport parameters under the compressed state. For the sake of artificial intelligence, the prediction accuracy on the pore and solid structures is dramatically improved up to 98 % consistency when compared with the analytical solution, by identifying the true shape of cylindrical carbon fibers. The three-dimensional U-net algorithm was incorporated into the conventional X-ray computed tomography, to gain a complete separation of carbon fiber and binder. Subsequently, the origin of two different microstructures in the through-plane direction, i.e. transitional surface region and core region, are investigated as a function of compression ratio (CR). Finally, the structure-property relationship of CFP is thoroughly evaluated over a wide range of the paper thicknesses, PTFE contents and CRs. We demonstrate that the microstructural three-dimensionality, which is one decisive factor determining the transport and electrochemical properties in energy devices, can be further analysed by exploring the formation factors of solid and pore structures with increasing CRs. The insights gained from this work not only enhance the fundamental understanding of CFP microstructures but also pave the way for optimizing the design and operation of next-generation energy devices, promising a more efficient and sustainable energy landscape. [Display omitted] • AI-based tomographic method is introduced for porous energy materials such as CFP. • Digital twins of compacted CFP distinguishing pore and solid structures is realized. • Origin of core/transition region is verified by varying thickness and PTFE contents. • Binder orientation affects in-plane gas permeability in CFPs under compression. • Formation factors converged to ε2–2.5 and ε3–4 under in-plane and through-plane directions. [ABSTRACT FROM AUTHOR]

[Display omitted] The design and synthesis of advanced electrodes with high conductivity and flexibility are the key to the development of wearable energy storage devices. Herein, a strategy for preparing conductive carbon paper electrode for flexible supercapacitors is reported by vacuum filtration of a mixture of biomass hierarchical porous carbon materials (HPC), cellulose nanofibers (CNFs) from polysaccharide cellulose of plant origin and silver nanowire (AgNWs), in which CNFs serve as substrates for dispersion and crosslinking of HPC. The prepared self-supporting electrode showed multi-scale pore structure and excellent conductivity (14.1 S cm−1). The electrode exhibited the highest specific capacitance of 383 F g−1 at 0.5 A g−1. Even after 10,000 charge and discharge cycles, 95 % of the original capacitance was remained, which means excellent cyclic stability. High strength and flexibility of the as-assembled flexible supercapacitor make the electrochemical performance of this device remain unchanged when bent at any angle. The present research delineates a simple and convenient method to prepare green, efficient and low-cost flexible supercapacitor. [ABSTRACT FROM AUTHOR]

The paper proposes a new approach to gradient porous composites based on the Ti3Al(Si)C2 MAX phase. This approach is based on the production of preceramic paper with the different content of the powder filler based on MAX phases and their spark plasma sintering. The analysis of the microstructure and phase composition is conducted for these composites. It is shown that the obtained composites have a clear interface between layers with different porosity. It is found that the content of organic components in preceramic paper affects the phase composition of the fabricated composites. The MAX phase content in dense and porous layers is 86 and 56 vol.%, respectively. Microhardness measurements performed in the composite cross-section show the hardness of 600 to 800 HV, depending on the layer porosity and phase composition. [ABSTRACT FROM AUTHOR]

Understanding the phenomenon of liquid wicking in porous media is crucial for various applications, including the transportation of fluids in soils, the absorption of liquids in textiles and paper, and the development of new and efficient microfluidic paper-based analytical devices (μPADs). Hence, accurate and real-time monitoring of the liquid wicking process is essential to enable precise flow transport and control in microfluidic devices, thus enhancing their performance and usefulness. However, most existing flow monitoring strategies require external instrumentation, are generally bulky and unsuitable for portable systems. In this work, we present a portable, compact, and cost-effective electronic platform for real-time and wireless flow monitoring of liquid wicking in paper strips. The developed microcontroller-based system enables flow and flow rate monitoring based on the capacitance measurement of a pair of electrodes patterned beneath the paper strip along the liquid path, with an accuracy of 4 fF and a full-scale range of 8 pF. Additionally to the wired transmission of the monitored data to a computer via USB, the liquid wicking process can be followed in real-time via Bluetooth using a custom-developed smartphone application. The performance of the capacitive monitoring platform was evaluated for different aqueous solutions (purified water and 1 M NaCl solution), various paper strip geometries, and several custom-made chemical valves for flow retention (chitosan-, wax-, and sucrose-based barriers). The experimental validation delivered a full-scale relative error of 0.25%, resulting in an absolute capacitance error of ±10 fF. In terms of reproducibility, the maximum uncertainty was below 10 nl s−1 for flow rate determination in this study. Furthermore, the experimental data was compared and validated with numerical analysis through electrical and flow dynamics simulations in porous media, providing crucial information on the wicking process, its physical parameters, and liquid flow dynamics. [ABSTRACT FROM AUTHOR]

Paper is a material made from renewable resources, and it has been used intensively for almost 2000 years. It is a highly porous, bendable, and foldable flat structure of randomly arranged and connected fiber-like basic building blocks. The capability to transport fluids without pumps and sophisticated dosing systems is attractive. Paper microfluidics especially has gained increasing interest, particularly in the last decade. Although a number of interesting demonstration devices for easy-to-use diagnostic systems have been reported, only a limited number of these have found applications. This is mainly due to the geometric and chemical complexity of the material. While chemical functionalization (e.g., for defining hydrophobic barriers for spatially resolved fluid transport) is well advanced, understanding and controlling capillary-driven transport of a fluid within the complex porous matrix of paper. This article highlights recent advances and outlines design strategies for successful microfluidic paper-based applications. [ABSTRACT FROM AUTHOR]

Paper used in the printing industry generally contains a relatively thin porous coating covering a thicker fibrous base layer. The three-dimensional pore structure of coatings has a major effect on fluid flow patterns inside the paper medium. Understanding and quantifying the flow properties of thin coating layers is hence crucial. Pore spaces within the coating have an average size of about 180 nm. We used scanning electron microscopy combined with focused ion beam (FIB-SEM) to visualize the nano-scale pore structure of the paper coating layer. Post-processing of the FIB-SEM images allowed us to reconstruct the three-dimensional pore space of the coating. The 3D FIB-SEM images were analyzed in detail to obtain pore size distribution and porosity value. The permeability was estimated using the GeoDict software, based on solutions of the Stokes equation. By determining the porosity and permeability of increasingly larger domain sizes, we estimated the size of a representative elementary volume (REV) for the coating layer to be 60 µm 3 , which is well within the volume analyzed using FIB-SEM. The estimated porosity and permeability of the REV domain were 0.34 and 0.09 mDarcy, respectively. Using the pore morphology method, capillary pressure-saturation ( P c - S ) and relative permeability curves of the REV domain could be constructed next. The P c -S curves showed that the coating had a high air entry suction, which is very favorable for printing in that ink will invade the coating as soon as it is applied to the coating. Our results are essential for macroscale modelling of ink penetration into a coating layer during inkjet printing. Macroscopic models can be valuable tools for optimization of the penetration depth and the spreading of ink on and within paper substrates. [ABSTRACT FROM AUTHOR]

Coated paper is an example of a multi-layer porous medium, involving a coating layer along the two surfaces of the paper and a fibrous layer in the interior of the paper. The interface between these two media needs to be characterized in order to develop relevant modeling tools. After careful cutting of the paper, a cross section was imaged using focused ion beam scanning electron microscopy. The resulting image was analyzed to characterize the coating layer and its transition to the fibrous layer. Such image analysis showed that the coating layer thickness is highly variable, with a significant fraction of it being thinner than a minimum thickness required to keep ink from invading into the fibrous layer. The overall structure of the coating and fibrous layers observed in this analysis provide insights into how the system should be modeled, with the resulting conclusion pointing to a specific kind of multi-scale modeling approach. [ABSTRACT FROM AUTHOR]

ABSTRACT The production of traditional cellulose paper not only consumes lots of timber, but also brings about some environmental issues. Therefore, it is being increasingly replaced by synthetic paper. In this study, ultrahigh molecular weight polyethylene (UHMWPE)/SiO2 synthetic paper with high application performance was prepared by the thermally induced phase separation method using mineral oil as diluent. The corresponding properties of synthetic paper, including surface morphology, overall porosity, tensile strength, thermal stability, acid and alkali resistance, whiteness, and inkjet print effect were investigated respectively. The results show that the overall porosity of UHMWPE/SiO2 synthetic paper is above 45%, and the tensile strength exceeds 4.3 MPa. UHMWPE/SiO2 synthetic paper also presents light weight, as well as good resistance to heat, acid and alkali. Meanwhile, the average whiteness of the samples is up to 91.8%. The sample K-50, which contains 31.5 wt % SiO2, takes on the best print performance caused by its dense surface and higher SiO2 content. It is indicated that UHMWPE/SiO2 synthetic paper has good market prospects in the color printing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41529. [ABSTRACT FROM AUTHOR]

The transport properties of gas diffusion layer (GDL) in proton exchange membrane fuel cell are important parameters in fuel cell modelling, and one method to measure them is to simulate the transport of each species at spatial resolutions of a few microns in a microstructure of the GDL. One issue in this method is the size of the microstructure as using an unnecessarily big sample could substantially increase the computational cost. Both carbon-paper and carbon-cloth GDLs are investigated and their microstructures are obtained using numerical generation and X-ray micro-tomography respectively at a resolution of 1.733 µm. For each reconstructed GDL, we use the orthorhombic lattice Boltzmann model to simulate fluid flow through some subsamples taken from it in both the in-plane and the through-plane directions; the results show that the permeability of all subsamples is anisotropic in that their permeability in the in-plane direction is higher than in the through-plane direction. For each GDL, we compare its permeability calculated using samples of different sizes and find its representative elementary volume (REV) – a volume above which the calculated permeability represents the average ability of the GDL to conduct fluids. [ABSTRACT FROM AUTHOR]

The title of the current Special Issue, "Feature Papers in Materials Simulation and Design", has identified the aims of this collection since its opening: the gathering of research works and comprehensive review papers that advance the understanding and prediction of material behavior at different scales, from atomistic to macroscopic, through innovative modeling and simulation. The paper by Chen et al. [[4]] aimed at studying the thermal properties and thermoelectric performance of imidazole-graphyne (ID-GY) by combining first principle calculations with the Boltzmann transport theory. The last paper by Cheng and Vescovini [[16]] presented instead an accurate and efficient numerical method for the analysis and design of Variable Stiffness (VS) laminates. Civalek et al. [[11]] developed an efficient eigenvalue algorithm for the axial vibration analysis of embedded short-fiber-reinforced micro-/nano-composite rods subjected to arbitrary boundary conditions. [Extracted from the article]

Constructing low-cost, high-catalytic-performance anode electrocatalysts is a significant challenge for methanol oxidation (MOR) and urea oxidation (UOR) reactions. Using paper templates with abundant pores to prepare thin porous metal materials helps to obtain high-performance electrode materials. The nano amorphous B-doped Ni/crystalline Ni (nanoam Ni-B/Ni) foil composite electrodes were derived from paper templates prepared by impregnation, high-temperature reduction, and electrodeposition methods. Porous Ni foils (Nip) derived thinnest rice ("Xuan") paper, initially used for Chinese calligraphy and painting, exhibits the best performance due to its strong adsorption and wettability. Compared to direct current electrodeposition, pulse electrodeposition yields finer amorphous B-doped Ni nanoparticles with good catalytic performance. Under a current density of 100 mA·cm−2, the nanoam Ni-B/Ni composite electrode prepared under a duty cycle of 0.5–1.0 s achieved current densities of 290.4 mA·cm−2 (MOR) and 340.4 mA·cm−2 (UOR) at 0.8 V, which are improved by 37.1% and 55.1%, respectively, compared to those of Nip. After 2000 cycles, with solution replacement, the current densities maintained 99.2% (MOR) and 81.6% (UOR) of the original values, showing excellent electrocatalytic stability. This research provided a new use for Chinese rice paper, and the prepared Nip-based electrode, with a thickness of about 60 μm and a low area quality, had a simple preparation process and good electrochemical properties, and can be used as a potential substitute for commercial Ni foam for portable or small electrochemical devices. [ABSTRACT FROM AUTHOR]

We leverage electroosmotic-flow generation in porous media in combination with a hydrophobic air gap to create a controllable valve capable of operating in either finite dosing or continuous flow mode, enabling the implementation of multi-step assays on paper-based devices. The hydrophobic air gap between two paper pads creates a barrier keeping the valve nominally closed. Electroosmotic actuation, implemented using a pair of electrodes under the upstream pad, generates sufficient pressure to overcome the barrier and connect the two pads. We present a model describing the flow and governing parameters, including the electric potentials required to open and close the valve and the threshold potential for switching between the modes of operation. We construct the air gap using a hierarchical superhydrophobic surface and study the stability of the closed valve under strenuous conditions and find good agreement between our model and experimental results, as well as stable working conditions for practical applications. We present a straightforward design for a compact and automated device based on paper pads placed on top of printed circuit boards (PCB), equipped with heating and actuation electrodes and additional power and logic capabilities. Finally, we demonstrate the use of the device for amplification of SARS-CoV-2 sequences directly from raw saliva samples, using a loop-mediated isothermal amplification (LAMP) protocol requiring sample lysis followed by enzymatic deactivation and delivery to multiple amplification sites. Since PCB costs scale favorably with mass-production, we believe that this approach could lead to a low-cost diagnostic device that offers the sensitivity of amplification methods. [ABSTRACT FROM AUTHOR]

Keywords: biomass; carbonization; CO2 cycloaddition; ionic liquids; paper mill sludgeUpcycling Waste BiomassIn article number 2300655, Marcileia Zanatta, Marta C. Corvo, and co‐workers show that, by transforming paper industry waste into porous carbonaceous materials, these materials serve as effective supports in the ionic liquid‐catalyzed cycloaddition of CO2 to styrene oxide, achieving high conversion rates and selectivity..By Mónica Stanton Ribeiro; Maria M. R. A. Lima; Márcia Vilarigues; Marcileia Zanatta and Marta C. CorvoReported by Author; Author; Author; Author; Author [Extracted from the article]

Porous media made of nitrocellulose and glass fiber are common “paper” substrates for lateral flow assays, microfluidic paper analytical devices and other point-of-care diagnostic assays. Such assays commonly use optical labels such as gold nano-particles, latex beads, or fluorescent nanoparticles to visualize the presence of analytes. Fluorescent labels are commonly used in bioassays to enhance sensitivity, but autoluminescence of the paper substrate worsens signal-to-noise ratios of fluorescence-based assays. To date, there exists no systematic investigation of autoluminescence wavelengths or lifetimes of porous membranes used in lateral flow assays. In response, we quantified the autoluminescence of commonly used porous materials across the visible spectrum via excitation—emission spectroscopy and timeresolved fluorescence spectroscopy, and demonstrate that autoluminescence is solely due to autofluorescence with lifetimes of about 5 ns in the visible spectrum. Counterintuitively, we found that spectroscopy alone does not provide sufficient information to select candidate paper substrates for fluorophore-labeled assays. Therefore, we developed a simple quantitative framework to select a low-fluorescence substrate that minimizes both the overlap of paper and fluorophore emission spectra and the fluorescence intensity on an imaging system of interest (such as a gel imager). Use of this framework was shown to lower the limit of detection of an influenza A nucleoprotein immunoassay by over 50%. The tools developed in this manuscript enable assay developers to screen appropriate, low-fluorescence porous substrates and enhance the sensitivity of membrane-based fluorescence assays. [ABSTRACT FROM AUTHOR]

Microfluidic devices with a free-standing structure were printed directly on polymer films using the functional materials that form interconnected pores. The printed devices can transport fluids by capillary action in the same fashion as paper-based microfluidic devices, and they can handle much smaller sample volumes than typical paper-based devices. Detection of glucose was performed using both colorimetric and electrochemical methods, and the observed limits of detection (LOD) were similar to those obtained with paper-based microfluidic devices under comparable testing conditions. It is demonstrated that printed microfluidic devices can be fabricated using printing processes that are suitable for high-volume and low-cost production and that the integration of microfluidic channels with electrodes is straightforward with printing. Several materials that are printable and form interconnected pores are presented. [ABSTRACT FROM AUTHOR]

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]

Abstract: The carbon paper is synthesized by the simple, cheap and large-scale pyrolysis of filter paper and is used as an interlayer for Li–S battery. The as-prepared carbon paper is composed of carbon fiber with porous structure. The specific surface area is 534m2 g−1, and the average pore size is 4.1nm. The porosity of the as-prepared carbon paper lies in favor of the electrolyte permeating through the layer, which allows electrochemical reactions to occur. The prepared carbon paper is used as an interlayer between the cathode and the separator in Li–S battery and can significantly improve the electrochemical performance of the cell with reversible capacity, cycling ability, and rate capability. [Copyright &y& Elsevier]

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]

Paper microfluidics is a rapidly growing subfield of microfluidics in which paper-like porous materials are used to create analytical devices that are well-suited for use in field applications. 3D printing technology has the potential to positively affect paper microfluidic device development by enabling tools and methods for the creation of devices with well-defined and tunable fluidic networks of porous matrices for high performance signal generation. This critical review focuses on the progress that has been made in using 3D printing technologies to advance the development of paper microfluidic devices. We describe printing work in three general categories: (i) solid support structures for paper microfluidic device components; (ii) channel barrier definition in existing porous materials; and (iii) porous channels for capillary flow, and discuss their value in advancing paper microfluidic device development. Finally, we discuss major areas of focus for highest impact on the next generation of paper microfluidics devices. [ABSTRACT FROM AUTHOR]

The pursuit of disinfecting porous materials or fomites to inactivate viral agents has special challenges. To address these challenges, a highly portable chlorine dioxide (ClO2) gas generation system was used to ascertain the ability of a gaseous preparation to inactivate a viral agent, the MS2 bacteriophage, when associated with potentially porous fomites of cloth, paper towel, and wood. The MS2 bacteriophage is increasingly used as a model to identify means of inactivating infectious viral agents of significance to humans. Studies showed that MS2 bacteriophage can be applied to and subsequently recovered from potential porous fomites such as cloth, paper towel, and wood. Paired with viral plaque assays, this provided a means for assessing the ability of gaseous ClO2 to inactivate bacteriophage associated with the porous materials. Notable results include 100% inactivation of 6 log bacteriophage after overnight exposure to 20 parts per million(ppm) ClO2. Reducing exposure time to 90 minutes and gas ppm to lower concentrations proved to remain effective in bacteriophage elimination in association with porous materials. Stepwise reduction in gas concentration from 76 ppm to 5 ppm consistently resulted in greater than 99.99% to 100% reduction of recoverable bacteriophage. This model suggests the potential of ClO2 gas deployment systems for use in the inactivation of viral agents associated with porous potential fomites. The ClO2 gas could prove especially helpful in disinfecting enclosed areas containing viral contaminated surfaces, rather than manually spraying and wiping them. [ABSTRACT FROM AUTHOR]

Abstract: A commercially available GDL based on carbon paper or carbon cloth as a macroporous substrate was characterized by various physical and electrochemical measurements: mercury porosimetry, surface morphology analysis, contact angle measurement, water permeation measurement, polarization techniques, and ac-impedance spectroscopy. SGL 10BB based on carbon paper demonstrated dual pore size distribution and high water flow resistance owing to less permeable macroporous substrate, and more hydrophobic and compact microporous layer, as compared to ELAT-LT-1400W based on carbon cloth. The membrane-electrode-assembly fabricated using SGL 10BB showed an improved fuel cell performance when air was used as an oxidant. The ac-impedance response indicated that a microporous layer which has high volume of micropores and more hydrophobic property allows oxygen to readily diffuse towards the catalyst layer due to effective water removal from the catalyst layer to the gas flow channel. [ABSTRACT FROM AUTHOR]

Porous 3-D current collectors have been shown to be the primary choice in replacing classical 2D aluminum foil in applicable developments, especially those using carbon-based current collectors. In this study, we investigated the impact of using a non-woven carbon (NWC) based current collector for sulfur electrodes, in terms of performance and practical use in a commercial battery, keeping in mind the simplicity of electrode preparation method. The benefits of using NWC as a 3D current collector include high sulfur utilization for even highly loaded electrodes, lower polarization, and the provision of an efficient electrolyte reservoir. High discharge capacities up to ∼1200 mAh g −1 can be obtained at moderate C-rates, with relatively good capacity retention (<1% loss per cycle) and practical loadings as high as 8 mAh cm −2 . [ABSTRACT FROM AUTHOR]

ABSTRACT Composite materials made from fibrous support coated with agro-polymers are widely commercialized for different applications. But, their transfer properties have only been sparingly studied despite their importance in membrane technologies or food packaging. Furthermore, most of past studies on the topic have been focused on the impact of surface properties of the support on the final coated material structure and its properties; leaving unexplored the potential impact of the in-bulk structure of the support. This study demonstrated the influence of in-bulk structure and especially fibers refining degree of 4 kraft papers (SP28, 36, 60, and 80) on the structure, and surface and gas transfer properties of their respective wheat gluten (WG) coated papers (WGP28, 36, 60, and 80). Paper presenting a high fibers refining degree (SP28) exhibited very tight and narrow in bulk fibers network which prevented most of the WG-coated layer penetration, maintaining an important WG apparent layer on top of the paper and a small fibers/wheat gluten composite zone inside (WGP28). Such structure gave strong 'WG-like' properties to the final coated material with moderate oxygen permeation and high permselectivity (1.50 × 10−11 mol m−2 s−1 Pa−1 and 8.09, respectively for WGP28) whereas the highly impregnated structure of coated papers built on lowly refined papers (SP80, with wide and loose structure) gave coated materials presenting weak 'WG-like' properties, supposedly due to a thick composite zone presenting interfacial defects, with higher oxygen permeation and very limited permselectivity (11.90 × 10−11 mol m−2 s−1 Pa−1 and 1.06, respectively for WGP80). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2848-2858, 2013 [ABSTRACT FROM AUTHOR]

The article presents a study about the use of use polarized light reflectometry technique in analyzing a wide-scale of coated papers from pulp mills in the U.S. The polarized light reflectometry technique measures roughness and refractive index of the surface which can help in examining the surface porosity properties. The study aims to show how the technique can provide information about surface porosity, composition, and structure. The study reveals that the technique is useful for investigating of the coating structure and explains the source of gloss. However, the technique needs further applications and materials to be studied to examine its consistency.

In high-solids surface sizing of up to 30% solids, less starch penetrates the sheet, which means the sheet requires less drying. However, less penetration means the internal strength does not benefit from the starch as much as it does in conventional surface sizing. To compensate for this loss of internal strength, the Huygen internal strength of surface-sized paper can be increased by reducing the press draw from 3% down to 2% or lower. Starch penetration is further reduced, however, when the press-to-dryer draw is decreased because the lower press draw decreases the porosity of the basesheet. Moreover, reducing the press draw to less than 2% decreases the elastic modulus of the fiber network and reduces the bending stiffness of the sheet. [ABSTRACT FROM AUTHOR]

The direct use of environmental paper waste (PW) to create spongy aerogel intended for oil absorption is an interesting green chemistry technique. The oil sorption response, on the other hand, is constrained by a poor oil sorption capacity and lack of stability. To address these concerns for the time being, silica aerogel is being used. Our goal is to use PW aerogel to replace silica aerogels. We made an environmental PW-based aerogel by dispersing PW, polyvinyl alcohol (PVA), and glutaraldehyde (GA). In terms of oil sorption the hybrid PW aerogel performs wonderfully. Notably, it displayed a significant absorption capacity towards various oils of approximately 49–110 times its own mass, dependent on the thickness and density of the oil and solvents within 15–35 s, 25 °C, and 2 × 2 cm dimensions. Additionally, owing to the high sponginess (99.95%), and less density (0.0114 g/cm3), tight bonding between PW and PVA occurs. As a results, the spongy aerogel has an oleophilic nature, superior mechanical power, and high thermal strength. The consistent fibrillar pore linkage gives a high surface to volume ratio, low surface energy, as well as high surface roughness, the aerogel undergoes minimal structural change after numerous recycles. All of these elements have a role in excessive oil absorption. [Display omitted] • A hybrid paper waste (PW) aerogel was created and used for oil absorption. • The homogeneous MTMS surface coating on aerogel has a 147.20o water contact angle. • Aerogel is a porous material (99.95%) with a network of connected fibrillar pores. • The absorption capability of 49–110 times its own mass towards various oils. • Aerogel has a remarkable stability up to 15 recycling reactions. [ABSTRACT FROM AUTHOR]