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Significant dimensional variations may occur in paper-based materials when subjected to changes in moisture content. Moisture induced deformations are governed by the swelling of individual fibres, which is transferred through inter-fibre bonds to the entire fibrous network. Complex interactions between mechanical and hygro-expansive properties take place in the bonding areas, affecting the overall material response. In most network models, the role of these inter-fibre bonds is not explicitly incorporated. This work presents a periodic meso-structural model for the discrete fibrous network, which considers the free-standing fibre segments and inter-fibre bonds. Despite its simplicity, the reference unit-cell enables the incorporation of relevant micro- and meso-structural features such as network structure, fibres and bond geometry and hygro-elastic properties. The proposed model is solved analytically through a proper homogenization strategy, allowing to recover the paper’s anisotropic hygro-mechanical response in terms of effective elastic constants and effective hygro-expansive coefficients, exploiting the coupling at the meso-structural level between hygroscopic and mechanical behavior. A comparison with experimental results obtained from the literature shows that the presented approach is quite accurate in predicting the overall paper response, thereby revealing the influence of several meso-scale parameters (e.g. fibre orientation, dimensions, mechanical strength). [ABSTRACT FROM AUTHOR]

The nanofibrillated cellulose (NFC) was used as substrates to carry triclosan (TCS), which was then applied as a coating agent for impacting antibacterial property to paper while also improving its strength. The TCS-loaded NFC material was further characterized. UV–vis spectra results showed that a characteristic absorption band at 282 nm was observed, which was attributed to triclosan, confirming its successful loading onto NFC. The antibacterial activity tests indicated that the coated paper exhibited excellent antibacterial activity against Escherichia coli , and the growth inhibition of bacteria (GIB) increased as the loading amount of triclosan coated on paper increased. The GIB can reach 98.7% when the 0.023 g TCS-loaded NFC was coated on paper. Meanwhile, the tensile and tear index of the coated paper increased by 18.0% and 26.4%, respectively compared to the blank paper. Therefore, the triclosan-loaded paper could be potentially used in the medical field. [ABSTRACT FROM AUTHOR]

The synthesis of carboxymethylcellulose was investigated using effluents containing short cellulose fibers. Carboxymethylcellulose was synthesized according to the slurry process using different amount of sodium hydroxide and different incubation times at 30°C after the etherification reaction as variables. Characterization of the product was conducted by Fourier transformed infrared spectroscopy, X-ray diffraction, degree of substitution, average degree of polymerization, water imbibing capacity, color, rheological properties, apparent viscosity and trace elements content. Incubation time slightly increased the yield of the reaction and the degree of substitution during the first 12 h. The reaction yield and degree of substitution both decreased when the initially concentration of NaOH was increased from 7.0 g/mL to 10.5 g/mL. The carboxymethylcellulose obtained was darker and had lower hydration properties than commercial samples. Trace elements content suggests that the product could be only used in paint factories or building materials industries. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods: an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. [ABSTRACT FROM AUTHOR]

The saltwater immersion method was developed to inhibit mould growth on flood- or tsunami-damaged paper. Commercially available fine paper used for printing and writing showed decreased tensile indices after saltwater immersion. The salt remaining in the paper tended to increase the moisture content because of the salt deliquescence and moisture in the air. The tensile index was restored by removing salt from the paper. Crystallization and distribution of salt in interfibre pores were also considered to influence interfibre rebonding. The difference in the fibre responses to saltwater depended on the relationship between nano-scaled pores in the fibre walls, osmotic pressure, and the degree of sizing, which resulted in low water retention values. More of the starch applied as a surface sizing agent was dissolved or dispersed during distilled water immersion than saltwater immersion. This loosened the fibre network, which was a factor that decreased the sizing degree of the paper. [ABSTRACT FROM AUTHOR]

To understand the applicability of the termination indicators for landfill municipal solid waste (MSW) with low initial lignin content, four different accelerated landfill stabilization techniques were applied to anaerobic landfilled waste, including anaerobic flushing with water, anaerobic flushing with Fenton-treated leachate, and aerobic flushing with Fenton-treated and UV/H 2 O 2 -treated leachate. Termination indicators, including total organic carbon (TOC), ammonia-N (NH 4 + -N), the ratio of UV absorbance at 254 nm to TOC concentration (SUVA 254 ), fluorescence spectra of leachate, methane production, oxygen consumption, lignocellulose content, and humus-like content were evaluated. Results suggest that oxygen consumption related indicators used as a termination indicator for low-lignin-content MSW were more sensitive than methane consumption related indicators. Aeration increased humic acid (HA) and (HA + FA)/HyI content by 2.9 and 1.7 times compared to the anaerobically stabilized low-lignin-content MSW. On the other hand, both the fulvic acid (FA) and hydrophilic (HyI) fractions remained constant regardless of stabilization technique. The target value developed for low-lignin-content MSW was quite different than developed countries mainly due to low residual biodegradable organic carbon content in stabilized low-lignin-content MSW. [ABSTRACT FROM AUTHOR]

Here we present a new and rapid immunofiltration assay for simultaneous detection of HIV p24 and hepatitis B virus antigens. The assay platform is composed of a 13 mm nitrocellulose filter spotted with capturing bioprobes and inserted in a Swinnex ® syringe filter holder. Samples and reagents are flown through the nitrocellulose filter by manual pressure on the syringe. A colorimetric detection allows for naked eye results interpretation. The assay provides sensitivity in the picomolar range in just 5 min, even using low volumes of sample in complex matrix. Probe deposition by spotting allows for flexible combinations of different capturing agents and multiple diagnoses; furthermore, the very simple and inexpensive set-up makes the syringe-based immunoassay on paper microarray a suitable diagnostic system for resource-limited settings. [ABSTRACT FROM AUTHOR]

Extrusion coating experiments of flame retarded low density polyethylene (LDPE) onto a standard machine finished Kraft paper have been carried out. A pilot extrusion coating line was used in order to investigate the potential of halogen-free flame retardant system based on azoalkanes such as azocyclohexane (AZO) and 4′,4-bis(cyclohexylazocyclohexyl)methane (BISAZO) for fire resistant coating applications. In comparison, experiments were performed using FlameStab ® NOR116, magnesium dihydroxide (MDH) and a brominated additive Luvogard MB81/PE as reference flame retardants. The concentration of azoalkane flame retardants was varied between 0.5 and 1 wt.%. The maximum extrusion temperature was varied between 260 and 290 °C and the coating layer weight from 12.9 to 25.0 g/m 2 . The obtained multilayer facings containing azoalkanes exhibited significantly improved flame retardant properties, especially at the low coating weight of 12.9 g/m 2 . Under all of the used experimental conditions the runnability on the pilot line was flawless for azoalkane formulations. In contrast, our pre-trials using MDH/LDPE (50:50) formulations failed due to poor film quality and visible white aggregates. Moreover, the multilayer facings containing the FlameStab ® NOR116, Luvogard MB81/PE or mixtures thereof, showed inferior flame retardant properties compared to azoalkane based facings. [ABSTRACT FROM AUTHOR]

From the analysis of the production process of molded pulp packaging, it can be seen that one of the residues generated in the molding is “pulp”. When this waste cannot be reincorporated into the production line, is recovered by centrifugation in the effluent treatment system. With the intention of recycling this residue it was investigated the feasibility of their use in the manufacture of concrete blocks or panels lightened studying possible ways to use the material, either in the wet state (form is discharged from the process) or dry (dried in a controlled environment), analyzing the advantages and disadvantages of each alternative. For practical purposes, various dosages were proposed to maintain constant the amount of residue and varying the amounts and proportions of water and cement. Test specimens were made with various amounts of cement per m 3 of concrete. [ABSTRACT FROM AUTHOR]

The present study aims to investigate how resource strategies, which intend to reduce waste and increase recycling, influence on human exposure to hazardous chemicals from material recycling. In order to examine the flows of hazardous chemicals in recycled material, a mass flow analysis of plastics and paper at European level, including the flow of phthalates, i.e. di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and benzyl-butyl phthalate (BBP), has been performed. The result for the year 2012 shows that 26% of plastic wastes and 60% of paper consumed in Europe were recycled. This corresponds to the finding that approximately 4% of DEHP and BBP and 18% of DBP annual demands in Europe as raw material re-enter the product cycle with recycled plastics and paper. To examine the potential contribution of the phthalate exposure through recycled plastics and paper, a case study assessing the childhood exposures to phthalates from foods packed in recycled paper and plastics has been performed for 2-year-old children in Denmark. The result verifies that an increase in recycled paperboard and PET bottles in food packaging material causes a significant increase in childhood exposure to DBP corresponding to an additional exposure of 0.116–0.355 μg/kg bw/day; up to 18% of the total DBP exposure in Danish 2-year-olds. While most of the DEHP exposure can be explained, more than 50% of DBP and 70% of BBP exposure sources still remain to be identified. Finally, a conceptual framework for a circular economy based on sustainable and clean resource flows is proposed in order to increase material recycling without increasing adverse health effects. [ABSTRACT FROM AUTHOR]

Pulp and paper mills generate large amounts of waste organic matter that may be converted to renewable energy in form of methane. The anaerobic treatment of mill wastewater is widely accepted however, usually only applied to few selected streams. Chemical oxygen demand (COD) removal rates in full-scale reactors range between 30 and 90%, and methane yields are 0.30–0.40 m 3 kg −1 COD removed. Highest COD removal rates are achieved with condensate streams from chemical pulping (75–90%) and paper mill effluents (60–80%). Numerous laboratory and pilot-scale studies have shown that, contrary to common perception, most other mill effluents are also to some extent anaerobically treatable. Even for difficult-to-digest streams such as bleaching effluents COD removal rates range between 15 and 90%, depending on the extent of dilution prior to anaerobic treatment, and the applied experimental setting. Co-digestion of different streams containing diverse substrate can level out and diminish toxicity, and may lead to a more robust microbial community. Furthermore, the microbial population has the ability to become acclimated and adapted to adverse conditions. Stress situations such as toxic shock loads or temporary organic overloading may be tolerated by an adapted community, whereas they could lead to process disturbance with an un-adapted community. Therefore, anaerobic treatment of wastewater containing elevated levels of inhibitors or toxicants should be initiated by an acclimation/adaptation period that can last between a few weeks and several months. In order to gain more insight into the underlying processes of microbial acclimation/adaptation and co-digestion, future research should focus on the relationship between wastewater composition, reactor operation and microbial community dynamics. The potential for engineering and managing the microbial resource is still largely untapped. Unlike in wastewater treatment, anaerobic digestion of mill biosludge (waste activated sludge) and primary sludge is still in its infancy. Current research is mainly focused on developing efficient pretreatment methods that enable fast hydrolysis of complex organic matter, shorter sludge residence times and as a consequence, smaller sludge digesters. Previous experimental studies indicate that the anaerobic digestibility of non-pretreated biosludge from pulp and paper mills varies widely, with volatile solids (VS) removal rates of 21–55% and specific methane yields ranging between 40 and 200 mL g −1 VS fed. Pretreatment can increase the digestibility to some extent, however in almost all reported cases, the specific methane yield of pretreated biosludge did not exceed 200 mL g −1 VS fed. Increases in specific methane yield mostly range between 0 and 90% compared to non-pretreated biosludge, whereas larger improvements were usually achieved with more difficult-to-digest biosludge. Thermal treatment and microwave treatment are two of the more effective methods. The heat required for the elevated temperatures applied in both methods may be provided from surplus heat that is often available at pulp and paper mills. Given the large variability in specific methane yield of non-pretreated biosludge, future research should focus on the links between anaerobic digestibility and sludge properties. Research should also involve mill-derived primary sludge. Although biosludge has been the main target in previous studies, primary sludge often constitutes the bulk of mill-generated sludge, and co-digestion of a mixture between both types of sludge may become practical. The few laboratory studies that have included mill primary sludge indicate that, similar to biosludge, the digestibility can range widely. Long-term studies should be conducted to explore the potential of microbial adaptation to lignocellulosic material which can constitute more than half of the organic matter in pulp and paper mill sludge. [ABSTRACT FROM AUTHOR]

Ground wood cellulose paper exhibits a practicable cleaning laser fluence window during middle-UV radiation processing. In this case, a minimum dose volume density should be applied. However, cleaning of bleached cellulose paper is accompanied by strong yellowing and destruction. The presence of charcoal graphite particulates shows substantial influence on the yellowing with increasing coverage. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a thermal conversion process that can be an environmentally beneficial approach for the conversion of municipal solid wastes to value-added products. The influence of using activated sludge and landfill leachate as initial moisture sources during the carbonization of paper, food waste and yard waste over time at 250 °C was evaluated. Results from batch experiments indicate that the use of activated sludge and landfill leachate are acceptable alternative supplemental liquid sources, ultimately imparting minimal impact on carbonization product characteristics and yields. Regression results indicate that the initial carbon content of the feedstock is more influential than any of the characteristics of the initial liquid source and is statistically significant when describing the relationship associated with all evaluated carbonization products. Initial liquid-phase characteristics are only statistically significant when describing the solids energy content and the mass of carbon in the gas-phase. The use of these alternative liquid sources has the potential to greatly increase the sustainability of the carbonization process. A life cycle assessment is required to quantify the benefits associated with using these alternative liquid sources. [ABSTRACT FROM AUTHOR]

Highlights: [•] The impact of digital technologies on writing and reading is investigated in Finland. [•] The positive affordances of writing on paper are similar to those found in Italy. [•] Students consider important to write a lot, quickly and instantly without losing time. [•] A keyboard is a point of reference for all comparisons in students’ responses. [ABSTRACT FROM AUTHOR]

Silver nanoparticles with a mean diameter of approximately 30 nm were synthesized by reduction of silver nitrate with triethanolamine in the presence of polyacrylic acid. Silver nanoparticle-based ink was prepared by dispersing silver nanoparticles into a mixture of water and ethylene glycol. The mechanism for the dispersion and aggregation of silver nanoparticles in ink is discussed. The strong electrostatic repulsions of the carboxylate anions of the adsorbed polyacrylic acid molecules disturbed the aggregation of metal particles in solutions with a high pH value (pH > 5). An inkjet printer was used to deposit this silver nanoparticle-based ink to form silver patterns on photo paper. The actual printing qualities of the silver tracks were then analyzed by variation of printing passes, sintering temperature and time. The results showed that sintering temperature and time are associated strongly with the conductivity of the inkjet-printed conductive patterns. The conductivity of printed patterns sintered at 150 °C increased to 2.1 x 107 S m-1, which was approximately one third that of bulk silver. In addition, silver tracks on paper substrate also showed better electrical performance after folding. This study demonstrated that the resulting ink-jet printed patterns can be used as conductive tracks in flexible electronic devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carboxymethyl cellulose (CMC) was oxidized to form dialdehyde CMC (DCMC). [•] Guanidine hydrochloride (GH) was grafted onto the DCMC to obtain DCMC-GH. [•] The coating of DCMC-GH onto paper resulted in the improvement of paper strength. [•] The DCMC-GH-coated paper exhibited excellent antimicrobial activities. [Copyright &y& Elsevier]

Paper-structured catalysts were prepared using ceramic fibers by a wet papermaking technique, followed by the deposition of ruthenium hydroxide on the fiber-network microstructures. As-prepared flexible paper catalysts possessed large geometric surface areas with micrometer-size pores. The paper-structured catalysts exhibited high catalytic efficiency for selective aerobic oxidation of aromatic and aliphatic alcohols to their corresponding aldehydes and ketones, in a fixed bed multiphase reactor. Hydrodynamic behavior in the reactor filled with either paper or bead catalysts was evaluated by measuring the residence time distribution in a cold flow model. It was revealed that the paper composites exhibited good wettability and internal diffusion of liquid substances compared with ceramic beads, showing heterogeneous liquid flow. Efficient catalytic oxidation of various alcohols was achieved using the paper-structured catalysts because uniform fluid dynamic behavior formed a thin liquid layer on the catalyst surfaces, possibly resulting in favorable gas–liquid–solid interfaces. [ABSTRACT FROM AUTHOR]

Highlights: [•] We prepared a series of paper sheets incorporating titania-anchored hollow silica. [•] The papers showed high photocatalytic activity in the degradation of ethanol. [•] A new model coupling mass transfer and UV penetration has been developed. [•] The simulated UV profiles suggest a strong UV attenuation within the paper thickness. [•] Counter- and co-current modes show comparable photocatalytic activities. [Copyright &y& Elsevier]

Abstract: The commercially available copy papers and pure papers have been adopted to synthesize carbon nanomaterials. It is found that carbon nanocoils (CNCs) are efficiently synthesized on the copy paper substrates using Fe2(SO4)3/SnCl2 catalyst by a thermal chemical vapor deposition method, while only carbon nanotubes (CNTs) are obtained on the pure paper substrate using the same process. It is evidenced that the particles of calcium carbonate existing in copy paper aggregate catalyst and adsorb more sulfur elements which promote the growth of CNCs. In addition, CNCs can successfully grow out from the pure paper by adding calcium carbonate. [Copyright &y& Elsevier]

Highlights: [•] We deposited multi-wall carbon nanotubes on carbon fiber paper with a simple CVD. [•] We investigated the inherent mechanism of Ni particle's self-dispersion. [•] The MWCNTs/CFP composite possesses wonderful electrical conductivity. [ABSTRACT FROM AUTHOR]

Highlights: [•] We are interested in how the characteristics of paper affect the printing reproduction. [•] Paper with higher surface roughness has lower color gamut volume. [•] Paper with lower surface whiteness has lower color gamut volume. [•] Paper with higher surface gloss has higher color gamut volume. [ABSTRACT FROM AUTHOR]

A novel and binder free Co@graphite/paper electrode is prepared by electrodeposition Co nano-sheet on the surface of a graphite layer modified paper substrate. The morphology and phase structure of the Co@graphite/paper electrode are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer, transmission electron microscope and X-ray diffractometer. The catalytic activity of the Co@graphite/paper electrode for H 2 O 2 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the paper and exhibits a good stability. The oxidation current density reaches to 580 mA cm −2 in 2 mol dm −3 NaOH and 0.5 mol dm −3 H 2 O 2 at 0.5 V. Besides, we illustrate the reaction mechanization of the H 2 O 2 electrooxidation on the Co film. [ABSTRACT FROM AUTHOR]

Highlights: [•] The paper surface was rendered superhydrophobic via the phase separation of green-based waxes. [•] The key steps consisted of emulsifying, coating and annealing, which could be readily accomplished. [•] The entire process for superhydrophobic modification was free of organic solvent and fluorochemicals. [•] The wax coating layer showed good transparency and mechanical durability. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to increase the thermal resistance of a cellulose substrate, using films (a mixture of corundum-phase aluminum oxide, α-Al2O3, and a PVA solution). The corundum phase, which was chosen due to its high thermal resistance, was obtained using an adaptation of Pechini‘s polymeric precursor method. A polyvinyl alcohol (PVA) solution was used as a medium for mixing the oxide for subsequent deposition on a paper substrate. The materials were characterized by X-ray diffraction (XRD) and field emission gun scanning electron microscopy (FEG-SEM) coupled with energy dispersive X-ray spectrometry (EDS). The thermal behavior of the material was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). The EDS results indicate that all the samples with deposited α-phase aluminum oxide contain the chemical elements (Al and O) originating from the α-phase, while the surface analysis indicated that the paper substrates were completely coated with the films. The TG and DSC analyses of the thermal resistance of the film-coated substrate indicate that it was impossible to increase the thermal resistance of the paper substrate because the events that occurred (decomposition of cellulose and pyrolysis of lignin, hemicellulose and PVA) took place in the same temperature range, as has been reported in the literature for samples of the paper substrate without deposited film. [Copyright &y& Elsevier]

The mechanical properties of wood fiber-based, commercial papers and metal foils are qualitatively similar, and their plane stress, Mode I crack growth resistances have not been reliably correlated with single-valued fracture mechanics parameters for centimeter-scale specimens. Experimentally-measured crack tip strain fields of Mode I cracks growing in commercial paper were used to define a three-stage, steady-state crack growth mechanism. Immediately upon loading, the net sections ahead of the cracks yielded. As the cracks began to grow, well-defined zones of (incremental) active plasticity (ZAPs) formed within the yielded ligaments. Cracks transitioned to steady-state growth with an average characteristic stress, σ c , of 20.9 MPa. In contrast to metallic foils, the characteristic stress in steady-state cracks in paper was offset by 8.3 MPa due to a 1.9 mm fiber bridging zone that scaled with the average fiber agglomerate (floc) size. The fiber network structure also induced a large, reversed steady-state zone in the crack wakes. While reversed ZAPS were previously predicted by numerical models of plane strain Mode I and III cracks under small-scale yielding conditions, they were never observed experimentally and were neglected. The types and evolution of the cumulative and incremental plastic zones in paper defined appropriate paths for steady-state J -integral calculations. [ABSTRACT FROM AUTHOR]

Paper, in addition to its frequent usage in writing, packaging, printing, etc., has gained comprehensive utility as a flexible and conductive base in sensors, solar energy harvesting, conversion, and storage applications. This is due to its strategic-aiding aspect in terms of environmental friendliness, cost-effectiveness, recyclability, thin, flexible and lightweight nature, biocompatibility, etc., required to develop next-generation flexible devices. The signs of progress in paper-based devices are seen in matured technologies of the paper-based sensor for varied sectors. Also, there have been wide-ranging research efforts on developing paper-based high-performance energy harvesting, conversion, and storage solutions. However, it is a newly emerging area and needs a fundamental and state-of-the-art understanding for future devices development. Thus, the current review summarizes the research progress in this field utilizing paper, understanding fundamental properties w.r.t application, performance enhancement w.r.t material advancements (i.e. paper modification), and technological trends, which is otherwise not yet reviewed earlier. It further sheds light upon the perspectives for their associated and allied technological developments in the energy sector. [Display omitted] • Role of paper properties in energy related applications are discussed. • Paper based electrodes for energy harvesting and conversion devices. • Utilty of papers in energy storage i.e. supercapacitors and batteries is presented. • Challenges and perspectives of realization of paper based devices for energy sector are projected. [ABSTRACT FROM AUTHOR]

This paper gives a brief overview on the recent advances on photonic devices based on carbon materials such as: graphene waveguides or photonic devices on paper or plastic substrates in analogy with carbon based electronic devices. The four building block for electronics are the electrons as carrier's information's vectors, the generators, the cables and the transistors. In the same way, photonics or plasmonics will achieve in the future the capability to do same operations done actually in electronics by using photons or plasmons. Following the same steps as in electronics, new technologies were developed in photonics in order to produce photonic integrated circuits (PIC) first on silicon and more recently on plastic or paper substrates. If we analyze the present achievements we can notice that the already equivalent building blocks for photonics on paper substrates are already done: laser on paper substrate (as signal generators), optical and plasmonic waveguides (as information transport cables), optical and plasmonic transistors, photodetectors based on carbon materials etc. In this paper we present by analogy with electronics the recent advancements on paper and carbon based photonics devices. As for electronics, some of the most important advantages of these materials are that they are mechanically flexible, lightweight, cheap and environmentally friendly. • A briefly overview on technologies and materials for photonics on paper substrates. • State of art on perovskite materials for solar cells, LED and lasers. • State of art on plasmonic modulators based on graphene. • New perspectives for the development of future integrated photonic devices. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) is a foam-like porous material consisting of few-layer graphene obtained by laser irradiation of a wide range of carbon-containing substrates. Among these, the ability to synthesize LIG from paper and other cellulose-related materials is particularly exciting, as it opens the door to a wide assortment of potential applications in the form of low-cost, flexible, and biodegradable devices. Here, the synthesis of this material, dubbed paper-LIG , on different types of filter papers and xylan biopolymer is discussed. In particular, we report the formation of paper-LIG by single-step irradiation, providing an improvement over the conventional multiple lasing approach and giving an explanation of the conditions that allow this simplified synthesis. All the relevant process parameters are covered, assessing their effect on the resulting electrical properties, structure, and morphology. Additionally, we demonstrate the application of LIG obtained from xylan, an abundant and often underutilized biopolymer, for temperature sensing. These results provide a better understanding of the conditions required for the synthesis of highly conductive LIG from paper and related materials, paving the way for its application, with reduced cost and low environmental impact, in fields ranging from biomonitoring to consumer electronics. [Display omitted] • Synthesis of laser-induced graphene from filter paper by a single irradiation step • Synthesis of laser-induced graphene by irradiation of filter paper containing activated charcoal • Laser-induced graphene from a xylan substrate, valorizing this underutilized natural product • Temperature sensor employing laser-induced graphene obtained from modified xylan [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have been investigated as a promising device to harvest mechanical energy into electricity. At present, paper-based triboelectric nanogenerators (P-TENGs) have been widely researched because paper features with lightweight, low cost, abundance, renewability and biodegradability. In this paper, the operating principles and operation modes of TENGs, the development progress and performance enhancement routes of P-TENGs are comprehensively reviewed. Additionally, the overview, challenges and opportunities of P-TENGs applications are also presented. [ABSTRACT FROM AUTHOR]

Vertically aligned ZnO nanowire arrays on the paper substrate are integrated into a novel, sound-driven, piezoelectric nanogenerator device. The intrinsic impedance of the circuit causes phase differences between the input and output signals. For the input sound of around 40 db, an AC output voltage of about 5 mV is achieved. Because of the paper substrate allows the acoustic energy to dissipate, the fabricated device has detected a 4.88 db loss in the input sound signal. [ABSTRACT FROM AUTHOR]

In this study, a probabilistic analysis of the critical velocity for an axially moving cracked elastic and isotropic plate is presented. Axially moving materials are commonly used in modelling of manufacturing processes, like paper making and plastic forming. In such systems, the most serious threats to runnability are instability and material fracture, and finding the critical value of velocity is essential for efficiency. In this paper, a formula for the critical velocity is derived under constraints for the probabilities of instability and fracture. The significance of randomness in different model parameters is investigated for parameter ranges typical of paper material and paper machines. The results suggest that the most significant factors are variations in the crack length and tension magnitude. [ABSTRACT FROM AUTHOR]

Highlights: [•] Modeling of cutting forces while applying a slicing motion to the push-cutting process. [•] Analysis of state of stress at the cutting edge. [•] Stress Intensity Factors for cutting with a symmetrical and asymmetrical cutting knife. [•] Fracture toughness of the paper sheet material is determined through DENT test. [•] The new model is verified by sideways push-slice cutting stacked thin paper material. [Copyright &y& Elsevier]

This research evaluates the use of microblasting technique with powdered cellulose as a new tool for dry cleaning documents. Different cleaning tests were conducted on three documents with different properties following this new approach and the results were compared to those obtained with traditional dry cleaning with erasers. In order to assess changes caused to the supports, the treated documents were examined both before and after cleaning with optical and 3D stereomicroscopy, SEM-EDS and spectrophotometry. The results allow the conclusion that microblasting with powdered cellulose is a feasible technique to remove surface dirt or grime on paper documents. This research proves that the new use of the technique does not entail changes to the surface properties of the treated supports. Moreover, powdered cellulose is chemically stable and compatible with paper documents, preventing negative long-term effects derived from the presence of rubber residues that may remain in paper fibres when using erasers in dry cleaning treatments. [ABSTRACT FROM AUTHOR]

Abstract: A new composite paper with high photocatalytic performance has been successfully manufactured by introducing titania-anchored porous silica into cellulose fibres. The silica particles with an average size of 700nm were synthesized via CaCO3 templating and further employed as support to grow titania nanoparticles (5.2nm) by sol–gel synthesis with variable weight ratios. The photocatalytic materials have been characterized using various techniques including BET, XRD, Raman spectroscopy, SEM and TEM+EDX+ED microscopies. The composite TiO2/SiO2 particles have been further introduced in bulk paper to generate highly active photocatalytic TiO2-loaded papers. The activity of the papers has been demonstrated in the room-temperature degradation of ethanol (50–200ppm) under UV irradiation, showing a comparable activity to that of commercial TiO2-coated papers. The effect of the main textural variables during papermaking on the photocatalytic performance are discussed in detail. [Copyright &y& Elsevier]

Commercial copy paper is a thin sheet material that has orthotropic constitutive behavior reminiscent of Al foils. Similar to Al foils, mode I crack tips in paper developed quasistatic, fully plastic, steady-state conditions even though plastic deformation in paper is not isochoric. The characteristic steady-state stress for crack growth depended on specimen orientation and contained a positive offset stress due to fiber bridging ( σ c = 37.3 MPa, σ offset = 6.0 MPa and σ c = 20.1 MPa, σ offset = 2.9 MPa for the machine and cross direction orientations, respectively). Orientation-dependent, reversed plastic zones were observed in the crack wake and transverse necking fracture processes were not present. • Steady-state, mode I crack growth was observed in single-edge notched specimens. • Steady-state process zone sizes were directly measured from full-field strain maps. • The crack growth was controlled by a characteristic steady-state stress. • The characteristic steady-state stress was offset because of fiber bridging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel dimer acid-based waterborne polyurethanes (DWPUs) were designed and prepared. • DWPUs were first used as multifunctional coatings for paper substrates. • Papers coated by DWPUs exhibited excellent water- and oil-resistances. • Alkyl and uniform membrane of DWPUs are critical to improve papers' properties. Paper derived from lignocellulose has great advantages over plastics as packaging material, nevertheless, the poor water- and oil-resistances of paper-derived products limited their application in high-end field. Herein, novel dimer acid-based waterborne polyurethanes (DWPUs) with different content of dimer acid-based polyester polyol (DG) were prepared and used as water- and oil-resistant coating for paper substrate. The effects of DG contents on water- and oil-resistances, mechanical properties and thermal stability of DWPUs coated papers were systematically investigated. When the content of DG reached up to 7 wt% (based on polyester glycol), the paper coated by DWPU exhibited 88.06% decrease in Cobb 60 value, 8.7 times increase in kit rating compared with uncoated paper. Meanwhile, DWPUs coated papers showed good mechanical properties and thermal stability. These improvements are attributed to the flexible long-alkyl chain, and six-ring structure of DWPUs as well as the continuous and homogeneous DWPU-derived membrane on the surface of paper. This study provides a new framework for the preparation of high quality, multifunctional, environmentally friendly water- and oil-resistant coatings for paper substrates. [ABSTRACT FROM AUTHOR]

We first reported a novel visualized instrument-free signal conversion method on paper for cardiovascular biomarker detection based on the coffee-ring effect (CRE). Our strategy was based on the principle that cTnI was captured by DNA probe decorated detection antibody to form sandwich complex, which could hybridize with H1 probes to form G-quadruplex DNAzyme. As a peroxidase mimic, G-quadruplex DNAzyme could catalyze colorimetric reaction and generate colored products, which were converted to the end edge of the paper by evaporation-driven flow, forming a visible colored band. Hence, the resulted colored signals were converted to distance signal by CRE, so that the quantification of cTnI could be measured easily only by a ruler. Our results demonstrated that the length of the colored bands was proportional to the concentration of cTnI, with a limit of detection of 1.0 pg/mL. Furthermore, this strategy not only showed advanced performance to discriminate cTnI from complex samples but also exhibited high accuracy with standard method in real sample. Hence, these results demonstrated that this method established a promising equipment-free and visualized platform for detecting various kinds of genetic diseases and biomarkers, further promoting the development of point-of-care testing (POCT) in biomedicine. • A visual Cardiovascular Biomarker detection strategy was developed. • The resulted colored signals were converted to distance signal by CRE. • This method developed equipment-free and visualized platform. [ABSTRACT FROM AUTHOR]

Paper is a material exhibiting a complex microstructure that is composed of a network of fibres at the micro-level. When subjected to external loading or variations in moisture conditions over different time scales, changes in strain that are non-linear with respect to time are observed at the sheet level (macro-scale). In order to investigate this time-dependent behaviour of paper, a creep power law model is implemented within a finite element approach at the level of single fibres. This rate-dependent model is found to capture experimental results available in literature for single fibres with a good agreement (both quantitatively and qualitatively). Based on the identified model at the level of single fibres, the time-dependent hygro-mechanical response is upscaled towards the network scale. To this end, random model networks of ribbon shaped fibres are generated and their response is simulated. The network-scale response, emerging from the rate-dependent fibre model, demonstrates the ability to predict the response of networks subjected to relaxation at a constant moisture level. The developed numerical model predicts lower values of overall stress response in single fibres as compared to networks. Also, stress relaxation predicted by the rate-dependent model in the cross-direction of the networks is in agreement with the experimental observations by Johanson and Kubát (1967). Therefore, one of the remarkable findings of the present work is that the developed rate-dependent model is robust enough to capture the sheet scale response also qualitatively. Based on the study of these computational results, a better understanding is achieved regarding the influence of mechanical and rate-dependent properties of single fibres on the hygro-expansion of complete fibre networks, and in particular of paper sheets. • A rate-dependent non-linear model is developed to study creep in paper networks. • It is calibrated with experiments on the single paper fibres with a good match. • It also captures the experimental response of the networks qualitatively. • One of the remarkable achievement of our work is the robustness of the model. [ABSTRACT FROM AUTHOR]

The detection of trypsin and its inhibitor is significantly important for both clinical diagnosis and disease treatment. Herein, we demonstrate a hydrogel-assisted paper-based lateral flow sensor for the detection of trypsin and its inhibitor for the first time. The gelatin hydrogel is hydrolyzed based on the gel-to-sol transition in the presence of trypsin, which results in the release of the trapped water molecules in the gelatin hydrogel. By placing one end of a pH indicator strip onto the hydrolyzed gelatin hydrogel, water is flowing along the pH indicator strip. However, in the absence of trypsin, water cannot flow along the pH indicator strip as the water molecules are trapped in the gelatin hydrogel. The detection limit of the system reaches as low as 1.0 × 10−6 mg/mL, and it is also applied to the quantitative detection of trypsin in human serum. In addition, the detection of a clinical drug aprotinin that is an inhibitor of trypsin is also successfully achieved. Noteworthy, only the gelatin hydrogel, pH indicator strip, and PS substrate are needed to fulfill the detection of trypsin without the need of other chemicals or reagents. Overall, we develop a particularly simple, elegant, robust, competitive, high-throughput, and low-cost approach for the rapid and label-free detection of trypsin and its inhibitor, which is very promising in the development of commercial products for sensing, diagnostic, and pharmaceutical applications. Besides, the hydrogel-assisted paper-based lateral flow sensor can also be employed to detect other analytes of interest by use of different stimuli-responsive hydrogel systems. • A hydrogel-assisted paper-based lateral flow sensor is developed for the detection of trypsin and its inhibitor. • The hydrolysis of the gelatin hydrogel by trypsin triggers release of the water trapped in the hydrogel. • The released water flows along a pH indicator strip, and the coverage ratio of the water mark is used to quantify trypsin. • This simple, convenient, and cost-effective method has high portability, remarkable sensitivity, and fast response time. • It shows excellent performance in label-free and high-throughput detection of trypsin in human serum. [ABSTRACT FROM AUTHOR]

To advance our understanding of the molecular biochemistry of fungi which impact cultural heritage in libraries, museums and archives we investigated the diagnostic capacity of Raman spectroscopy to identify the composition of colored chromophores of fungi on paper. In this study we explored the diagnostic capacity of resonant Raman to distinguish chromophores in fungal filaments stimulated to grow on paper under high humidity with a focus on characterizing chromophores of Alternaria group species. To facilitate molecular analysis, we conducted quantum chemistry calculations of representative metabolites having optical absorption in the ultraviolet–visible spectral range. Comparing theory and experiment we show that fonsecin, erythroglaucin and aurasperone type chromophores occur in mature hyphal filaments with β-carotene dominant in yeast depositions on paper surfaces. Resonant Raman of mature filaments suggests a further contribution of carotenes longer than β-carotene to the spectral signature. Using microscopic resolution, we distinguish rich sets of Raman signatures that we assign to lignin, flavoglaucin, riboflavin, cycloleucomelon(e) and asperyellone molecular components in the spatial regions where filaments initiate from yeast depositions. In such regions, where filament microstructures stimulate development of a mature three-dimensional scaffold, the diversity of Raman resonances confirms a rich biochemistry of the developing structures. The library of computed optical and spectroscopic responses of characteristic fungal chromophores and metabolites presented here is essential for understanding the effect of fungi on a wide range of objects made from paper including books, prints, drawings, watercolors, engravings and even sculptures as well as designing next generation materials based on fungal hyphal mats. • Non-invasive Raman spectroscopy can be used to identify pigments in fungi. • Quantum chemistry (DFT) combined with Raman for quantitative measure of chromophores. • Computed optical responses of fungal chromophores and metabolites. • Raman spectroscopy combined with Quantum chemistry as tools for cultural heritage. • Alternaria sp. generates specific pigments when grown on paper. [ABSTRACT FROM AUTHOR]

Paper-based packaging generally has poor performances in the gas/oil barriers. This work reports a paper-based packaging material prepared via the modification of conventional papers with TEMPO-oxidized cellulose nanofibers (TOCN)/cationic guar gum (CGG) hydrogel film. Specifically, the hydrogel film modification was realized through a layer-by-layer deposition on paper. The hydrogel film modification significantly improved the mechanical and barrier properties of the paper. Specifically, the 4-layer hydrogel film modified paper showed a tensile strength of 34.03 MPa and a burst strength of 510 kPa, respectively. In contrast, the unmodified paper exhibited a tensile strength of 26.78 MPa and a bursting strength of 388 kPa. The packaging performance of this TOCN/CGG hydrogel film modified paper was demonstrated via the fresh mooncake packaging test. Such hydrogel film not only provided the oil resistance, but also maintained the mooncake's freshness. This material can serve as a green and sustainable food packaging. [Display omitted] • A TOCN/CGG self-assembled hydrogel film modified paper reported • A 27% increase in tensile strength with the 4-layer hydrogel film modification • A kit number of 11 with the 4-layer hydrogel film modification • Freshness retention of mooncakes observed as packaged with modified paper [ABSTRACT FROM AUTHOR]

Tensile testing was used to measure the mechanical properties of paper at various orientations relative to the fiber alignment of paper. New, artificially aged, and naturally aged paper were shown to behave as orthotropic materials, as shown by the orientation dependence of the Young's modulus, E. The Young's modulus data could be fit to a simplified equation, indicating the shear modulus is relatively insensitive to the specific orientation. The shear modulus as measured by ultrasonic measurements was similar to that measured by fitting the modulus vs orientation data obtained by tensile testing to the orthotropic equation. The inelastic tensile strength could also be described by a simple non-linear equation, and there was more deviation of the data from this prediction for brittle papers than for non-brittle papers. The extent of fiber orientation (E x /E y) could be inferred by either the Young's modulus or the tensile strength, TS, i.e. E x /E y ≈ TS x /TS y. The measured strains were lowest for brittle paper. All brittle papers gave a strain to failure <1% whereas the non-brittle papers gave a strain to failure >1%. • Paper was shown to behave as an orthotropic material for new, artificially aged, and naturally aged papers. • The Young's modulus versus fiber orientation data could be fit to a simplified equation. • The shear modulus is relatively insensitive to the fiber orientation. • The Ramberg-Osgood equation can be used to describe the stress-strain measurements. • All brittle papers gave a strain to failure <1% whereas the non-brittle papers gave a strain to failure >1%. [ABSTRACT FROM AUTHOR]

[Display omitted] The translation of Surface Enhanced Raman Spectroscopy (SERS) from the laboratory to real-world applications such as point-of-need detection requires the fabrication of inexpensive yet quality substrates. Due to its flexibility, biodegradability, and 3D cellulosic structure, paper can be an excellent platform for the fabrication of low-cost, flexible SERS substrates that could expand the application of SERS to point-of-need sensing applications. In this mini-review, recent advances in paper-based SERS substrates along with various fabrication methods for plasmonic paper are discussed. The pros and cons of different fabrication methods are evaluated from the viewpoint of mass production. The different approaches to improving the performances of plasmonic paper substrates and additional analytical functionalities obtained from plasmonic paper substrates are discussed. Finally, opportunities and challenges in the realization of a low-cost commercial plasmonic paper substrate are also suggested. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pine needles lignocellulosic active paper incorporated with nanozeolite was fabricated. • The lignocellulosic paper showed improved water vapor transmission rate. • The lignocellulosic paper showed high ethylene scavenging properties. • Active pine needle based paper suitable for fresh produce active packaging. • Studies indicated valorization of pine needles biomass into paper fabrication. The pines needle falls approximately 2–3 ha−1 year−1 on the forest floors resulting in a considerable amount of lignocellulosic biowaste. The present study aimed to develop pine needles based lignocellulosic active paper and investigate the effect of 5, 20, and 30% (v/w) nano zeolite addition on the physical, mechanical, and microstructural property of the papers. The developed papers were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectrometer, and X-ray diffraction. As the zeolite concentration was increased from 5% to 30% in the paper, enhanced water permeability was seen from 5.18 ± 0.34 - 3.88 ± 0.33 g/cm2/day (PN/ZL 30% paper). The addition of 5% zeolite increased the tensile and burst strength from 19.53 ± 3.53 Nm/g and 3.63 ± 0.23 kg/cm2, respectively. The porosity was increased from 340 ± 20 to 1170 ± 60, and Cobb value increased from 338.3 ± 1.5- 406.7 ± 1.5 g/m2. The alterations in terms of surface microstructure in the paper with 20, 30% zeolite were noticed whereas XRD illustrated the high compatibility among the lignocellulosic network of pines and zeolite. The pine needle paper with 30% zeolite possessed remarkable ethylene scavenging properties (62%), opening a way to valorize pine needle waste for food packaging application. [ABSTRACT FROM AUTHOR]

• Bricks made by bottom ashes, cellulose fibers and clay have been successfully made and tested. • Optimum blends are made of 70% of clay, 25% of bottom ashes and 5% of cellulose fibers. • The so made bricks comply mechanical requirements and are 20% lighter. • Lower thermal conductivity and equal specific heat capacity is achieved. • Toxicity analysis abides by standards in force. The paper and pulp industry (PPI) is permanently searching for new ways of managing its residues due to the increasing pressure of new environmental concerns and policies adopted worldwide. In addition, the manufacturing of construction materials such as fired clay bricks (FCBs) is also facing the transformation of its traditional market, which is asking for new materials with a lower environmental footprint but equal or even better technological properties. In considering the large mass flows related to both the PPI and FCB industries, several researchers have pointed out the feasibility of replacing clay by residues produced by PPI. However, these approaches have always considered the replacement of a single residue rather than the addition of several new ones. Conversely, by using both residues at once, the overall FCB performance is improved and the feasibility of this circular economy approach is eased. For instance, the addition of woody fibres increases thermal resistance but reduces mechanical strength. Conversely, the addition of ashes produced by PPI improved the mechanical strength by reducing the thermal resistance due to the increasing content of fluxing agents which improve the fired clay matrix structure. For this reason, this paper explores the technological properties achieved by replacing clay with both ashes and fibres provided by PPI in an integrated approach. By following industrial procedures, the so made fired clay bricks (with 20% of ash and 5% of fibres) meet the standard and show approx. 20% less thermal conductivity, with the same thermal capacity and a density reduction of more than 15%. [ABSTRACT FROM AUTHOR]

• Multidisciplinary evaluation of three novel perennial crops as feedstock for the pulp and paper industry. • Meadow hay blends generated higher tensile indices compared to the pure birch control. • Fibre lengths of 0.5 (meadow hay), 1.3 (Virginia mallow), and 0.9 mm (cup plant) were measured. • The fibre widths of cup plant and Virginia mallow are broader compared to hardwoods. • These promising raw materials will be valueable in cardboard production for sustainable packaging. While the demand for paper and packaging material is increasing, industry and consumers are searching for more sustainable raw materials. This study evaluates three non-wood perennials to find alternative raw materials for the paper and pulp industry. Meadow hay, cup plant (Silphium perfoliatum L.) and Virginia mallow (Sida hermaphrodita (L.) Rusby) are attracting attention as potential raw materials for the bioeconomy due to biodiversity benefits, low fertilizer requirements as well as high yields. For the first time a detailed view on their fibre morphology and use as paper feedstock is given. After three different mechanical grinding methods, the plant material was screened, pulped in NaOH and beaten in a PFI mill. Birch fibre has been chosen as short-fibre control and blend base. Hand-sheets with different pulp blends of birch and one of the three raw materials were made, and paper properties were measured. For meadow hay, Virginia mallow and cup plant fibre lengths of 0.5, 1.3, and 0.9 mm were measured. Therefore, all perennial plant materials have comparable fibre lengths to hardwoods. Meadow hay blends with birch pulp percentages of 50 % and 75 % generated higher paper strength compared to the pure birch paper at a beating intensity of 5000 revolutions (PFI). The paper strength of cup plant and Virginia mallow blends is comparable to the strength of the birch control. Due to these promising results, all analyzed raw materials could find their application, especially in the growing area of sustainable packaging materials. [ABSTRACT FROM AUTHOR]

Flexible supercapacitor with all components monolithically integrated into an on-chip paper substrate demonstrates excellent electrochemical and mechanical performance. Supercapacitors are drawn with a conductive ink of nitrogen-doped carbon nanotube and graphene ink, which has been prepared without assistance of surfactant. The engineering strategy is intrinsically scalable toward flexible paper devices. [Display omitted] • A surfactant-free ink of nitrogen-doped carbon nanotubes and graphene is prepared. • The electrodes are integrated onto a paper in mirror image. • The resultant supercapacitor presents a high volumetric capacitance of 0.45 F cm−3. • The strategy is intrinsically scalable toward flexible supercapacitors. We demonstrate a facile strategy to fabricate flexible paper-based supercapacitors, in which all the components are integrated onto a paper with poly (vinyl alcohol)/H 3 PO 4 as the gel electrolyte. The electrodes are drawn on both sides of the paper in a mirror image with a surfactant-free ink of nitrogen-doped carbon nanotubes and graphene. The resultant supercapacitors present a high volumetric capacitance of 0.45 F cm−3 and an energy density of 40.0 μWh cm−3. Moreover, this strategy is intrinsically scalable toward flexible energy devices while maintaining their electrochemical and mechanical performance. [ABSTRACT FROM AUTHOR]

• Review of paper-based microfluidics. • Overview of current methods of fabrication. • Applications as diagnostic devices. • Limitations and opportunities. Paper-based microfluidics is the branch of microfluidics involving devices made out of paper, or other porous membranes, that wick fluids by capillary action. Paper-based microfluidic devices have several advantages over conventional microfluidic devices including simpler fabrication, lower cost, easier disposal, and the ability to operate without pumps or other supporting equipment. The most common application of paper-based microfluidic devices is in the development of point-of-care (POC) diagnostic devices, which could eliminate the need for costly and time-consuming laboratory-based analytical procedures. This review provides an overview of current methods of fabricating paper-based microfluidic devices, examples of applications of these devices, a discussion of their current limitations, and an outlook on their future. [ABSTRACT FROM AUTHOR]