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• White acrylic paint pigment is slightly alkaline and foxing-resistant. • Acrylic-gesso-coated watercolor paper can be used as an anti-foxing backing. • Acrylic gesso coating is simple & cost-effective against foxing. One of the concerns of watercolor artworks on paper is the natural oxidation process of the paper, leading to the development of unsightly yellow-brown spots referred to as foxing. Historically, efforts to preserve watercolor pieces in museums, institutions, and private collections have relied on intricate and expensive techniques. Unfortunately, these methods are not practical for the broader community of artists and less affluent collectors. Furthermore, the introduction of foreign preservation materials, which can interact with the artwork's components, poses a risk to the original visual appeal. Consequently, watercolor art collections have lost some of their appeal compared to oil paintings on canvases. This study endeavors to offer an alternative, straightforward, and cost-efficient approach to safeguarding watercolor artworks created on high-quality watercolor paper, a type commonly used by typical watercolorists, making it a suitable candidate for this investigation. This approach also avoids introducing additional substances to the artwork. The protective technique involves the application of commercially available acrylic gesso to a fresh sheet of watercolor paper. This gesso-coated paper serves as a backing for framing and displaying the original watercolor artwork, without the need for any foreign preservation materials to be added to the artwork itself. To assess the effectiveness of this protection method, a comparison was made between the foxing tendencies of protected and unprotected paper artworks stored for a decade. These samples were subjected to various analytical techniques, including optical microscopy (OM), confocal laser scanning microscopy (CLSM), field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX), X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA). The results revealed that, when compared to untreated samples, rarely any foxing spots were observed on any of the treated samples, and both the oxidation and degradation of cellulose fibers were diminished. Additionally, the analysis showed that the acrylic gesso comprised inorganic components such as calcium carbonate (CaCO 3), dolomite (CaMg(CO 3) 2), rutile (TiO 2), and organic acrylics. The carbonates created a mildly alkaline environment, neutralizing the acidity in the paper. The titanium dioxides exhibited biocidal and fungicidal properties due to their photocatalytic characteristics. The acrylic component bound and dispersed the inorganic constituents, and the coating formed a less impenetrable barrier layer as indicated by the scanning electron microscopy (SEM) results. In addition to significantly improving the resistance of the paper to foxing, the methods outlined in this study are highly cost-effective and readily accessible to artists and collectors. Importantly, they do not involve the addition of any restoration materials to the original artworks. [ABSTRACT FROM AUTHOR]

• BC/ZnO nanocomposite strengthens paper and improves aging resistance. • The nanocomposite imparts antifungal properties to paper. • The nanocomposite helps in deacidification of paper. Paper, commonly used as an information carrier, can become acidified and brittle over time. In this study, 0.3 % bacterial cellulose (BC) composite with 1.0% zinc oxide (ZnO) nanoparticles was prepared and used to coat brittle book paper for deacidification and consolidation. The BC/ZnO nanocomposite was characterized using zeta potential, micro morphology, elemental mapping, X-ray photoelectron spectra, Fourier transform infrared, and thermogravimetric analyses. The results indicated that the composite exhibited good stability. ZnO nanoparticles were bonded to the hydroxyl groups on BC, enhancing the thermal stability of BC. The composite was uniformly sprayed on the paper surface, and the mechanical properties, color difference, readability, pH, and micromorphology of the paper samples were examined before and after the treatment. The BC/ZnO nanocomposite exhibited good deacidification and consolidation effects on paper samples with low impact on the original paper appearance. Moreover, the BC/ZnO nanocomposite showed a good inhibitory effect on fungi growth on paper. [ABSTRACT FROM AUTHOR]

Paper with simultaneous fire-resistance and hydrophobicity have greatly potential applications in the fields of packing, storage and delivering information, which attracts increasing attention recently. Different from the traditional cellulose-based paper which is extremely easily damaged by water and fire, a new type of highly flexible, fire-resistant and hydrophobic paper based on Si 3 N 4 nanowires and polydimethylsiloxane (PDMS) is reported. Specially, the Si 3 N 4 @PDMS core-shell nanowires with 3D interlocking structure are designed, in which the Si 3 N 4 nanowires act as the inorganic fire-resistant frameworks and the PDMS shell with low surface energy provides the hydrophobic surface. The Si 3 N 4 @PDMS core-shell nanowires are intertwined and interlaced to form a highly flexible Si 3 N 4 @PDMS paper. The tensile strength of Si 3 N 4 @PDMS paper is 6.19 MPa, indicating the good mechanical property. The obtained Si 3 N 4 @PDMS paper has the characteristics of writability, fire-resistance and hydrophobicity. The high thermal stability of Si 3 N 4 nanowires makes Si 3 N 4 @PDMS paper exhibit excellent fire resistance. No obvious change is observed for the commercial paper with Si 3 N 4 @PDMS paper as the fire-shielding layer after heating for 30 min. In addition, the contact angles of water droplets are all greater than 110° over the surfaces of Si 3 N 4 @PDMS paper after mechanical damages, chemical corrosions and thermal treatments. Si 3 N 4 @PDMS paper can be used in oil/water separation and oil collection. More importantly, Si 3 N 4 @PDMS paper can be used for writing without being damaged by fire or water. The present work may inspire the development and application of functional paper and is expected to become a breakthrough in the traditional paper industry. [ABSTRACT FROM AUTHOR]

The development of self-powered UV photodiode on green substrate is still a challenge. In this study, highly conductive Al doped ZnO (AZO) film was sputter-deposited on paper substrate at room temperature; subsequently, paper-based Schottky photodiodes were successfully fabricated by following Au-ZnO-Al and Au-ZnO-AZO-Al structure designs, respectively. These UV light-based devices operate successfully without external power. Au-ZnO-AZO-Al photodiode shows improved response and faster speed compared to Au-ZnO-Al photodiode. The one-dimensional Poisson simulation results demonstrate that the improvement is attributed to the strong electric field in the ZnO-AZO n-n+ high-low junction, thus, enhancing the collection rate and drifting speed of the photogenerated carriers. In addition, AZO can form favorable ohmic contact with the Al electrodes, further improving the device performance. The photo-response of the paper-based photodiode device shows high reproducibility and stability. Based on these outstanding results, we conclude that these paper-based electronic devices have great potential to replace conventional petroleum-based flexible electronic devices, thus, contributing to the green/sustainable development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Food delivery boxes are tested for aerobic disintegration and anaerobic degradation. • Boxes made of paper only or with coatings (including polylactic acid) are analysed. • Paper is highly suitable for biological treatments behaving similarly to food waste. • Aerobic disintegration of coated boxes is much slower than that of paper only boxes. • Undigested polylactic acid coating is found in anaerobic semi-continuous tests. This study evaluated the fate of food delivery boxes when subjected to biological treatments, reproducing at the lab-scale the conditions of full-scale plants. Four paper-based boxes were composted: two made of paper only, one coupled with polylactic acid (PLA), and one with a barrier coating. One paper only box and the box with PLA were also investigated for their anaerobic degradability with biochemical methane potential (BMP) and semi-continuous tests. During composting, the boxes were not recognisable inside the compost after four (paper only boxes), eight (box with PLA), and twelve (box with barrier coating) weeks. In BMP tests, the paper only box showed a degradability similar to that of food waste (92 %), while the box with PLA degraded only at 76 %. Furthermore, undigested pieces of PLA were found in semi-continuous tests. Accordingly, paper resulted suitable for biological treatments, while the presence of PLA or other barrier coatings can be critical. [ABSTRACT FROM AUTHOR]

• Silk and sensitive paper was deteriorated by UV-radiation, NO 2 , and O 3 in museums. • Sensitive paper was also deteriorated by SO 2 at 4 µgm−3 and HCOOH at 50 µgm−3. • Intolerable degradation happened 6–7 times earlier in galleries than in enclosures. This paper reports 1 year of data of the environments and changes in the molecular weight of silk and the degree of polymerization of sensitive paper measured externally and indoors in 10 European museums, and the dose-response functions that were obtained by statistical analysis of this data. The measurements were performed in the EU FP5 project Master (EVK-CT-2002-00093). The work provides documentation of deterioration of silk by NO 2 and O 3 , and alternatively in combination with UV radiation. The indoor deterioration of the silk was only observed in one location with high UV radiation. The indoor deterioration of sensitive paper correlated with the UV radiation, the concentrations of NO 2 and O 3 , and in addition with an SO 2 concentration of 4 µgm−3 and a formic acid concentration of 50 µgm−3 in two different locations. If the observed dose-response effects are linear to lower doses and longer exposure times, then the lifetime to intolerable deterioration of the paper and silk would be 6–7 times longer overall in the enclosures than in the galleries. [ABSTRACT FROM AUTHOR]

• A cost-effective and eco-friendly polyDOPA@paper was prepared for DNA extraction. • The adsorption capacity of polyDOPA@paper for DNA was 20.7 μg cm−2. • An automated extraction system was designed to ensure results consistency. • The DNA extraction platform averts the need for specialized training of operators. • The platform combined with qPCR realized the detection of E. coli in milk samples. The success of polymerase chain reaction (PCR) depends on the quality of deoxyribonucleic acid (DNA) templates. This study developed a cost-effective and eco-friendly DNA extraction system utilizing poly(3,4-dihydroxyphenylalanine)-modified cellulose paper (polyDOPA@paper). PolyDOPA@paper was prepared by oxidatively self-polymerizing DOPA under weak alkaline conditions and utilizing the adhesive property of polyDOPA on different materials. Compared to the uncoated cellulose paper, polyDOPA coating significantly enhances DNA adsorption owing to its abundant amino, carboxyl, and hydroxyl moieties. The DNA extraction mechanism using polyDOPA@paper was discussed. The maximum adsorption capacity of polyDOPA@paper for DNA was 20.7 μg cm−2. Moreover, an automated extraction system was designed and fabricated using 3D printing technology. The device simplifies the operation and ensures the reproducibility and consistency of the results. More importantly, it eliminates the need for specialized training of operators. The feasibility of the polyDOPA@paper-based automated extraction system was evaluated by quantitatively detecting Escherichia coli in spiked milk samples via a real-time PCR. The detection limit was 102 cfu mL−1. The results suggest that the system would have significant potential in detecting pathogens. [ABSTRACT FROM AUTHOR]

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness — an outcome of a CMS layer forming atop the fiber base — which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hydroxyapatite (HAP) composite paper with biocompatibility and hygroscopicity was prepared. • HAP composite paper has better hygroscopic and triboelectric properties than pure paper, making it more suitable for wearable sensing applications. • The HAP composite paper-based triboelectric nanogenerator can detect and distinguish different joint movements. • Hemostatic and disposable HAP composite paper can be degraded in the natural environment without harm. Wearable triboelectric nanogenerators (TENGs) have attracted considerable attention in the field of self-powered sensors that can be worn on the skin directly without packaging because of their breathability, conformability, and sensitivity to collect biomechanical energy. However, high humidity on the skin can affect the wearable TENG output performance, substantially affecting the sensor performance and stability. When worn for a long time, humidity can even cause skin inflammation. Thus, for a wearable TENG, moisture control and biocompatibility are also key factors that need to be addressed. Herein, we report a hygroscopic and biocompatible paper-based TENG using a hydroxyapatite (HAP) mineral coating to enhance the paper fiber. The mineral coating can maintain the surface of the paper fiber, which will not cause large external deformation of the paper fiber under a force, avoid squeezing out excess water, and keep the friction surface dry, avoiding humidity affecting the output performance. Without interfering with the performance of the TENG, the maximum water absorption of the HAP composite paper is ∼8 μL. The HAP composite paper–based TENG (4 cm2) has an open-circuit voltage and short-circuit current 5.8 times and 4.2 times that of pure paper, respectively, and can obtain 80.4 mW/m2 output and directly light 117 LEDs. At relative humidity values of 25.7 %, 43.1 %, and 58.8 %, the performance retained the peak values of 80.2 %, 68 %, and 63.7 %, respectively. Even at a high relative humidity of 71.7 %, the triboelectric performance of HAP composite paper is retained 59.3 %, and the stability under humidity is better than that of pure paper (45.6 %). In addition, the mineral paper can even work with tissue fluid and output performance decreases by 43.8 %. The mineral-enhanced paper TENG with high power generation performance, hygroscopicity, biocompatibility, and degradability provides a new perspective for disposable wearable sensors, even in medical treatment. [ABSTRACT FROM AUTHOR]

Paper-based packaging is experiencing a resurgence due to its inherent biodegradability and recyclability. To meet the barrier properties required for certain applications, a coating is necessary. This coating must enhance functionality without compromising the environmental sustainability of the substrate. With this goal in mind, we prepared waterborne dispersions of biodegradable poly(lactic acid) (PLA) using a PEG-PLA-PEG triblock copolymer as the main surfactant. We achieved formulations with good stability over a 6-month period and high solids content (∼40 wt%). The waterborne dispersions underwent analysis by dynamic light scattering (DLS), size exclusion chromatography (SEC), gravimetric tests, and rotational rheology with and without xanthan gum (0.2–0.8 wt%) as a thickener. Subsequently, the thickened dispersions were coated at 60 °C onto a paper substrate. SEM analyses revealed the formation of a polymer layer on the paper surface with thickness and morphology dependent on the processing conditions. Partial interpenetration between the coating and the paper fibers was observed, resulting in excellent adhesion between the layers. The coated paper exhibited good barriers to liquid and water vapor, with Cobb60 < 5 g/m2 and water vapor transmission rate (WVTR) < 100 g/(m2∙day) for coating weights ≤15 g/m2, comparable to the performance of solvent-based PLA paper coatings. The surface energy of the coating was approximately 50 dyne/cm, higher than that of neat PLA, making it suitable for printing with common inks. Furthermore, the coated paper can be fully pulped in water, indicating that it can still be recycled in the paper stream, albeit with potentially increased processing time due to the coating weight. [Display omitted] • A PEG-PLA-PEG block copolymer was proven to stabilize waterborne PLA dispersions. • Dispersions with 40 % solid content were obtained. • The dispersions thickened with xanthan gum were successfully coated on paper at 60 °C. • PLA-coated paper had similar water barrier properties to its oil-based counterpart. • Repulping of PLA-coated paper is possible but slower than for uncoated paper. [ABSTRACT FROM AUTHOR]

Sensor arrays, which draw inspiration from the mammalian olfactory system, are fundamental concepts in high-throughput analysis based on pattern recognition. Although numerous optical sensor arrays for various targets in aqueous media have demonstrated their diverse applications in a wide range of research fields, practical device platforms for on-site analysis have not been satisfactorily established. The significant limitations of these sensor arrays lie in their solution-based platforms, which require stationary spectrophotometers to record the optical responses in chemical sensing. To address this, this review focuses on paper substrates as device components for solid-state sensor arrays. Paper-based sensor arrays (PSADs) embedded with multiple detection sites having cross-reactivity allow rapid and simultaneous chemical sensing using portable recording apparatuses and powerful data-processing techniques. The applicability of office printing technologies has promoted the realization of PSADs in real-world scenarios, including environmental monitoring, healthcare diagnostics, food safety, and other relevant fields. In this review, we discuss the methodologies of device fabrication and imaging analysis technologies for pattern recognition-driven chemical sensing in aqueous media. [Display omitted] • Cross-reactive sensors are applied to paper-based arrays for simultaneous detection. • Portable digital recorders can be used for detecting various responses. • Imaging analysis techniques can accelerate accurate data processing. [ABSTRACT FROM AUTHOR]

[Display omitted] • PVC-diphenylamine modified cellulose was proposed as sorptive phase. • The synthesis, using the dip-coating technique, is simple and cost-effective. • Opioids interact with the membrane by a mixed-mode interaction. • Direct infusion mass spectrometry allows to reduce the time of analysis. • The approach was successfully applied to real saliva samples containing codeine and tramadol. This article evaluates the potential of cellulose paper as a substrate for preparing a polyvinylchloride (PVC)-diphenylamine sorptive phase that can be used under the thin film microextraction (TFME) format. This phase was easily synthesized using the dip-coating technique to coat the filter paper with PVC, followed by the covalent bonding of diphenylamine. As a result, aromatics rings are available on paper surface to isolate the target analytes by a mixed-mode interaction at physiological pH. The resulting material was characterized by infrared spectroscopy, UV–Vis diffuse reflection spectroscopy, and scanning electron microscopy. As analytical problem, three opioids (methadone, codeine, and tramadol) were determined in saliva samples by direct infusion mass spectrometry. Different variables involved in the extraction procedure have been optimized (e.g. sample pH, extraction time, and sample dilution). The proposed method provides good linearity (R2 > 0.9817) and sensitivity (detection limits in the range from 1.5 µg L−1 to 15 µg L−1). The intra-day and inter-day precision, expressed as relative standard deviation, were better than 16.4 % and 18.5 % respectively. The accuracy, expressed as relative recovery, provides values in the interval from 82 % to 105 %. Finally, the proposed approach has been successfully applied to real saliva samples of patients under codeine and tramadol medical prescription. [ABSTRACT FROM AUTHOR]

Colored paper is an important industrial paper grade that has applications in various industrial sectors. The increase in coloring efficiency is a key in decreasing the use of dyes, thus can be considered as a "green" process concept; the coloring efficiency depends on the dye retention and dispersion. This work explores the use of nanocellulose, specifically, TEMPO-oxidized cellulose nanofibers (TOCNF), on the coloring efficiency of the preparation of colored paper. Two dyes (i.e. direct blue GL and reactive red 195 (RR195)) were used. Thanks to the large specific surface area and abundant active sites of TOCNF, its use largely improves the direct blue GL retention during the process. The coloring difference (∆E* ab) reached 5.334 with the addition of 13.6 wt% TOCNF and 1.8 wt% direct blue GL in the pulp furnish. The functional group in the dye is a vital factor in determining the dye retention when one chooses TOCNF to enhance the coloring efficiency in the production of colored paper. Furthermore, TOCNF significantly improved the strength properties of both direct blue GL and RR 195 dyed papers. This work demonstrates the potential of nanocellulose in the production of colored paper in improving the coloring efficiency, thus decreasing the environmental impact of the manufacturing process. [Display omitted] • Nanocellulose (i.e. TOCNF) adopted for colored paper preparation • Coloring efficiency improved by TOCNF due to the dye retention improvement • -COO− in TOCNF deteriorating its combination with negatively-charged dye [ABSTRACT FROM AUTHOR]

Improving the strength decrease caused by fungal metabolites is still an arduous task in the field of paper materials protection. A set of damaged Kangxi Dictionary from Qing Dynasty was chosen as samples in this work. The main goal of this work is to develop high-efficiency and eco-friendly media with the characteristics of antifungal and reinforcement, to preserve paper materials and continue the historical and scientific research value of cultural heritage. PHMG as an efficient antifungal was used in this work. For better behavior, the epoxy group of KH560 can be induced by the amino group in PHMG by ring opening reaction to form PHMG-KH560 colloidal complex. Spraying PHMG-KH560 on paper could establish Si-O-C bonding and increased the hydrogen bond between polymeric material and paper fibers, which simultaneously inhibited fungi and improved mechanical strength of the original paper, even after the artificial aging. PHMG-KH560 had certain antifungal activity against five fungi, such as Aspergillus versicolor, and Aspergillus Niger , and had better inhibitory effect on Cladosporium herbarum, Trichoderma viride , and Penicillium expansum. The ancient writing ink on the paper sprayed with PHMG-KH560 did not affect its visual beauty, which also indicated that the complex reagent was expected to be applied to the antifungal and reinforcement of paper materials. [ABSTRACT FROM AUTHOR]

The paper-based triboelectric nanogenerators (PB-TENGs) satisfied the requirement of sustainability and aroused great research interests, however how to improve their outputs still remains as a huge challenge. Most of the reported strategies to enhance the performance of PB-TENG focused on the chemical modification of the friction layers (FL), which may be restricted by the high-cost and cumbersome protocols being required. In this work, a general strategy of interface engineering to boost the outputs of the PB-TENG was proposed and validated by employing graphene composite paper (GC-paper) as electrodes. At the beginning, the hydroxyethyl cellulose (HEC) and Ecoflex were cured as separated films and used as friction layers, which were adhered with copper or GC-paper electrodes. The PB-TENG device can be obtained and possesses acceptable performance. Subsequently, we were surprised to find that the outputs of the PB-TENG largely increased by coating the FLs on the GC-paper rather than adhering. The maximum open-circuit voltage jumped from 300 V to 734 V, and the maximum short-circuit current boosted from 3.4 µA to 8.7 µA. This phenomenon may be ascribed to an interface effect between the FLs and electrodes, which enhanced the electrostatic induction. The strategy of this interface engineering was also proved to be general for other PB-TENG devices with various friction materials. Therefore, it may pave a way for the development of sustainable TENG devices with high performance. [Display omitted] • The output of the paper-based triboelectric nanogenerator (PB-TENG) was boosted. • A general strategy of interface fusion was demonstrated for the high performance. • The interface fusion was realized by coating frication layers on graphene-paper. • The PB-TENG was successfully used for energy harvesting and self-powered sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multi-layer forming technology can integrate triboelectric material with electrode. • The all CPTENGs can exhibit excellent humidity, acid and alkali resistance. • The CPTENGs can yield a V OC , I SC and power density of 227.1 V, 6.9 μA and 520 mW/m2. • Matching CPTENGs with P-ZISC can obtain a self-charging power system (PSCPS). • The PSCPS can drive some miniaturized electronics for a long time. Triboelectric nanogenerators (TENGs) are regarded as a promising technology to drive the development of flexible/wearable electronics and self-powering sensor. Application of cellulose paper as the triboelectric positive materials makes TENGs more environmentally friendly. However, the limited output performance and stability in harsh environments and oxidation and corrosion of the metal electrodes have limited the practical application of cellulose paper based triboelectric nanogenerators (CPTENGs). Here, we have integrated cellulose paper-based triboelectric material and electrode in one sheet by using multi-layer forming technology in paper industry; the upper triboelectric layer shows excellent triboelectric positive performance, hydrophobicity and acid and alkali resistance, while the bottom electrode exhibits promise conductivity. The all CPTENGs can yield a maximum open-circuit voltage (V OC) of 227.1 V, a short-circuit current (I SC) of 6.9 μA. Furthermore, the V OC values of the all CPTENGs increase from 0.02 V to 225.1 V at the load resistance of 100 Ω∼10 GΩ; and a power density of 520 mW·m−2 is also obtained at a load resistance of 30 MΩ. Moreover, the V OC of CPTENGs not only retains up to 78 % of its initial value at a high relative humidity of 90 %, but also almost maintains unchanged in a wide range of the pH environment (pH = 1∼13). More importantly, the CPTENGs can be readily matched with paper-based zinc supercapacitor (P-ZISC) to act as an all paper based self-charging power system (PSCPS). The PSCPS is capable of driving various miniaturized electronics, such as electronic watch, temperature/humidity indicator, demonstrating its potential application in a sustainable power source for portable and green electronics. [ABSTRACT FROM AUTHOR]

Cu2+ contamination and food spoilage raise food and drinking water safety issues, posing a serious threat to human health. Besides, Cu2+ and H 2 S levels indicate excess Cu2+-caused diseases and protein-containing food spoilage. Herein, a coumarin-containing bifunctional paper-based fluorescent platform integrated with a straightforward smartphone color recognition app is developed by an all-in-one strategy. The proposed fluorescent materials can simultaneously detect Cu2+ and H 2 S for on-demand food and drinking water safety monitoring at home. Specifically, a coumarin-derived fluorescence sensor (referred to as CMIA) with a low detection limit (0.430 μM) and high-selectivity/-sensitivity for Cu2+ is synthesized through a simple one-step route and then loaded onto commercially used cellulose fiber filter paper to engineer a biomass-based fluorescent material (CMIA-FP). The CMIA-FP offers user-friendly, high-precision, fast-responsive, and real-time visual monitoring of Cu2+. Moreover, CMIA forms a chemically stable complex with Cu2+, loaded onto filter paper to prepare another biomass-based fluorescent platform (CMIA-CU-FP) for visual real-time monitoring of H 2 S. Based on the exquisite composition design, the proposed dual-function paper-based fluorescent materials equipped with a smartphone color recognition program concurrently realize fast, accurate, and easy real-time monitoring of Cu2+ in drinking water and H 2 S in chicken breast-/shrimp-spoilage, demonstrating an effective detection strategy for the Cu2+ and H 2 S monitoring and presenting the new type of biomass-based platforms for concentrated reflection of drinking water and food safety. [Display omitted] • On-demand platform enabling simultaneously home-detecting Cu2+/H 2 S was proposed. • The platform realizes user-friendly, low-cost, fast-response detecting of Cu2+/H 2 S. • The platform achieves real-time monitoring of drinking-water and meat-storage safety. • The study provides effective tactics for the integrated Cu2+ and H 2 S home-detecting. [ABSTRACT FROM AUTHOR]

• Efforts to enhance PMFC performance are reviewed. • Both exciting advancements and current limitations are discussed. • An innovative strategy of multi-scale simultaneous optimization is proposed. Paper-based microfluidic fuel cell (PMFC) has attracted great attention in the microfluidic fuel cell field in recent years. It utilizes the spontaneous capillary flow of reactant solutions in paper-based porous substrate to achieve passive transportations of fuel and oxidant, solving the fluid driving issue encountered in traditional microfluidic fuel cells and thus having broad application prospects in medical detection, wearable devices, micro sensors, environmental monitoring, and many other fields. However, the commercialization of this technology is impeded by the low output performance caused by the limited mass and energy transfer in PMFCs. To enhance the mass and energy transfer in PMFCs, numerous research studies have been conducted via experimental optimization of the cell materials and structures. Numerical analyses focusing on the structure–activity relationship of PMFCs were also performed recently. To provide a comprehensive and thorough review about the efforts devoted to improving performance of PMFC, research papers relevant to PMFC since its invention in 2014 have been extracted in this work and significant works were filtered to highlight the exciting advancements. The experimental studies were classified and discussed based on the key components involved in the PMFC system, followed by a critical review of the limited computational models. Potential directions for future research were also provided, aimed at overcoming the current technological challenges in PMFCs. Importantly, an innovative strategy of multi-scale simultaneous optimization of the cell properties is proposed considering the typical multi-scale feature of the PMFC system, which could inspire the designing of advanced cell materials with optimal multi-scale structures for applications of PMFCs. [ABSTRACT FROM AUTHOR]

The assessment of the risk of virus transmission through papers, such as postcards, is important. However, the stability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (IAV) on different types of papers is currently unknown. Investigation of the survival time of these viruses on different types of papers will provide insights into their risk of long-distance transport by postal items. We evaluated the stability of SARS-CoV-2 and IAV, mixed with a culture medium, on the surface of postcards with various coatings, including plain paper (PP), inkjet paper (IP), and inkjet photo paper (IPP). The surface structure of each paper was microscopically assessed. The surface structures of PP, IP, and IPP varied greatly depending on the presence or absence, and type, of coat layer, regardless of the base material. IP and IPP surfaces were less conducive to virus survival than PP surfaces, because of the difference in surface shapes. The survival times of SARS-CoV-2 on each paper were approximately 59.8 (PP), 6.5 (IP), and 9.8 h (IPP), and significantly longer than those of IAV (10.3, 1.8, and 3.3 h, respectively). The risk of SARS-CoV-2 transmission via paper, such as postcards, is significantly higher than that of IAV transmission. While PP, IP, and IPP have the same base material, their surface structures differ, which affects viral stability. The IP and IPP surfaces are less suitable for virus survival. This study provides novel insights into the risks of viral transmission via paper. [ABSTRACT FROM AUTHOR]

• 72% − 80% of fibre was recovered from disposable coffee cups. • 2% and 3% consistency shredded cups required > 100 kWh/tonne to repulp with 3 refiner passes. • Pulp quality did not significantly diminish after repulping using a single-disk refiner. Over 64 billion paper-plastic laminate (PPL) coffee cups are consumed between the United States and Canada annually, the majority accumulating in landfills due to a hydrophobic plastic inner-lining. Recycling can mitigate environmental damage and provide economic value from repurposed products. We found that standard repulping methods were insufficient to separate fiber from plastic due to the low intensity of treatment. To increase process intensity, we mechanically refined shredded PPL coffee cups and Kraft eucalyptus sheets (control) at 2%, 3%, and 4% consistencies with three passes to determine the energy required to separate fibers from plastic and the effects on fiber quality. 2% and 3% consistency PPL cups measured under 40 kWh/tonne of input material for one refiner pass and ∼ 80 kWh/tonne for 4% consistency PPL cups. Recovered fiber fraction totaled 87.7%, 85.3%, and 80.5% of input mass of Kraft eucalyptus and 72.3%, 72.6%, and 79.6% of input mass of PPL cups at 2%, 3%, and 4% consistency, respectively. Fines content of PPL cups jumped from 8% pre-refining to ∼ 30% post-refining while Kraft eucalyptus fibers were unaffected, suggesting that breaking the plastic-fiber bonds results in fines generation. Mean fiber length of PPL cups slightly decreased with consistency and tensile strength improved. Freeness decreased with consistency only in PPL cup samples. These results demonstrate a low energy requirement to effectively separate fiber and plastics in PPL cups as well as minimal impact on fiber quality using existing refining technology, and provides an estimate of the financial costs of local recycling efforts. [ABSTRACT FROM AUTHOR]

• Artificial light radiation is a viable tool for paper documents bleaching. • Artificial light bleaching does not produce any physico-chemical change in paper. • Artificial light bleaching reduces the yellowing of paper in short and long term. • Paper is physico-chemical and optically deteriorated by hydrogen peroxide. This study offers a new tool to restorers to bleach paper documents: artificial light radiation (ALR). It is a controlled method that is an alternative to other highly aggressive procedures that have been applied to cellulose based media. Its main novelty is its intrinsic lighting characteristics which guarantee uniformity and avoid heating the paper. The results of testing this new tool were compared to those of bleaching with hydrogen peroxide (H 2 O 2). Each of the two methods was applied to five different types of widely used paper: Arches and Somerset (brands serving for engraving and digital printing), Ingres (drawing), press-type (magazines and newspapers) and Bible-type (historical documents). Once characterised by physico-mechanical, chemical and optical parameters (grammage, thickness, specular gloss, optical properties, air permeance, tensile properties, determining the pH of both surface and aqueous extracts), the different papers were bleached by the two methods according to pre-established criteria. Finally, to determine the evolution and effects of the two treatments, the papers were subjected to accelerated ageing. [ABSTRACT FROM AUTHOR]

A lignin-based PU coating was prepared for paper-based green packaging. Two representative diisocyanate were used to prepare the coatings. Due to the rigid aromatic, the physical properties of the TDI system reached the maximum below the lignin content of 40%. The HDI that contains flexible aliphatic chains alleviated the brittleness of coating, and it showed physical advantages when the lignin content was more than 50%. Owing to the high lignin content, the coating presented enhanced thermal stability. After coated with the lignin-based PU coatings, the dry tensile strength of coated paper was improved by 126%. Amazingly, the wet strength was increased from 0.31 to 12.6 MPa with an improvement nearly 40 times. Based on the coordination of lignin, Ag+ was introduced into the PU matrix, which imparted the coating with excellent antibacterial ability. The colony forming units of E. coli and S. aureus were both less than 1. However, no inhibition halo was observed, which indicated that the Ag was firmly anchored on the coating and the antibacterial ability is only available when the bacterial contact the coating surface. The lignin-based PU coating with favorable sustainability and properties shows great potential in paper-based green packaging fields. The prepared PU coating with high lignin content and firmly anchored Ag+ exhibits outstanding physical properties, thermal stability, and antibacterial property, which makes it an ideal candidate to be used in paper-based green packaging. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] With the rapid development of wearable intelligent devices, low-cost wearable strain sensors with high sensitivity and low detection limit are urgently demanded. Meanwhile, sensing stability of sensor in wet or corrosive environments should also be considered in practical applications. Here, superhydrophobic microcracked conductive paper-based strain sensor was fabricated by coating conductive Ti 3 C 2 T x MXene on printing paper via dip-coating process and followed by depositing superhydrophobic candle soot layer on its surface. Owing to the ultrasensitive microcrack structure in the conductive coating layer induced by the mismatch of elastic modulus and thermal expansion coefficient between conductive coating layer and paper substrate during the drying process, the prepared paper-based strain sensor exhibited a high sensitivity (gauge factor, GF = 17.4) in the strain range of 0–0.6%, ultralow detection limit (0.1% strain) and good fatigue resistance over 1000 cycles towards bending deformation. Interestingly, it was also applicable for torsion deformation detection, showing excellent torsion angle dependent, repeatable and stable sensing performances. Meanwhile, it displayed brilliant waterproof, self-cleaning and corrosion-resistant properties due to the existence of micro/nano-structured and the low surface energy candle soot layer. As a result, the prepared paper-based strain sensor can effectively monitor a series of large-scale and small-scale human motions even under water environment, showing the great promising in practical harsh outdoor environments. Importantly, it also demonstrated good applicability for spatial strain distribution detection of skin upon body movement when assembled into electronic-skin (E-skin). This study will provide great guidance for the design of next generation wearable strain sensor. [ABSTRACT FROM AUTHOR]

Frequent oceanic oil spill incidents and the discharge of industrial oily wastewaters have caused serious threats to environments, food chains and human beings. Lignin wastes with many reactive groups exist as the byproducts from bioethanol and pulping processing industries, and they are either discarded as wastes or directly consumed as a fuel. To make full use of lignin wastes and simultaneously deal with oily wastewaters, porous lignin-based composites have been rationally designed and prepared. In this review, recent advances in the preparation of porous lignin-based composites are summarized in terms of aerogels, sponges, foams, papers, and membranes, respectively. Then, the mechanisms and the application of porous lignin-based adsorbents and filtration materials for oil/water separation are discussed. Finally, the challenges and perspectives of porous lignin-based composites are proposed in the field of oil/water separation. The utilization of abundant lignin wastes can replace fossil resources, and meanwhile porous lignin-based composites can be used to efficiently treat with oily wastewaters. The above utilization strategy opens an avenue to the rational design and preparation of lignin wastes with high-added value, and gives a possible solution to use lignin wastes in a sustainable and environmentally friendly way. [ABSTRACT FROM AUTHOR]

Predictive models for the transport of volatile organic compounds in paper need to consider the complex interplay of diffusion, adsorption, desorption, or chemical reactions. The relative importance of each of these processes is determined by the polarity of the volatile. Hence, it is challenging to pick a valid theoretical model that correctly predicts transport regardless of the polarity. Here, physics-informed neural networks (PINNs) assess which of five different models correctly describe transport of DMSO as polar and n-tetradecane as apolar model compound: (i) a pseudo first-order adsorption model for an irreversible sorption process, (ii) a first-order kinetics model allowing reversible sorption, (iii) a second-order model with a reversible process, and an effective diffusion model accounting for a constant (iv) and for a variable effective diffusivity (v). Each tested model is given as set of partial differential equations (PDE). Considering the model under testing and experimentally obtained spatially and temporally resolved concentration profiles through stacks of paper sheets, PINNs predict concentration of the volatiles and associated material constants such as sorption constants and effective diffusion coefficients by solving the inverse problem. Our PINNs revealed two models, pseudo first-order sorption and second-order reversible sorption, that correctly predict concentration profiles and polarity-driven differences in sorption times. While a PINN-based picking of valid transport models has important implications for the development of effective methods for controlling emission of volatiles from paper materials, PINNs represent a versatile mathematical tool to validate or refute the capability of PDE-based theoretical models to describe experimental data. • PINNs evaluate sorption kinetics in porous materials. • Focus: Transport of organic volatiles in cellulose. • Pseudo first-order model suits organic volatiles. • Predicting transport of volatiles through paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Honeycomb panels with discrete arranged block reinforcements were numerically designed. • The elastic moduli of the new honeycomb panels are higher than those of heavier panels with slatted. • Tables with new cellular panels are characterized by a stiffness of 85 % of the stiffness of heavier tables with slats. Furniture manufacturers indicate they know the benefits of lightweight honeycomb panels but still expect their higher mechanical properties. This work presents a numerical and experimental approach to designing new tables manufactured of paper honeycomb panels with discreetly arranged reinforcing blocks in the core. The main goal was to determine whether the discrete arrangement of the blocks affects the strength and amount of energy absorbed by the newly designed tables and stiffness of honeycomb panels. Optimization reduced the weight of the panels by up to 30 %. At the same time, their linear elastic modulus was increased from 1579 MPa to 1771 MPa. After ten load cycles, tables with discrete reinforcements have a stiffness up 86.85–87.20 % of the stiffness of the reference table. After destructive tests up 89.96–91.16 %. Ultimately, the test results demonstrate the effectiveness of replacing wide slats with discreetly placed reinforcing blocks in the core structure. [ABSTRACT FROM AUTHOR]

Liquid penetration in porous cellulosic materials is crucial in many technological fields. The complex geometry, small pore size, and often fast timescale of liquid uptake makes the process hard to capture. Effects such as swelling, vapor transport, film flow and water transport within cellulosic material makes transport deviate from well-known relations such as Lucas-Washburn and Darcy's Law. In this work it is demonstrated how Ultra-Fast Imaging NMR can be used to simultaneously monitor the liquid distribution and swelling during capillary uptake of water with a temporal- and spatial resolution of 10 ms and 14.5–18 μm respectively. The measurements show that in a cellulose fiber sheet, within the first 65 ms, liquid first penetrates the whole sheet before swelling takes place for another 30 s. Furthermore, it was observed that the liquid front traps 15 v% of air which is slowly replaced by water during the final stage of liquid uptake. Our method makes it possible to simultaneously quantify the concentration of all three phases (solid, liquid and air) within porous materials during processes exceeding 50 ms (5 times the temporal resolution). We hence believe that the proposed method should also be useful to study liquid penetration, or water diffusion, into other porous cellulosic materials like foams, membranes, nonwovens, textiles and films. [Display omitted] [ABSTRACT FROM AUTHOR]

• An attempt to characterize thin, low impedance paper at various high strain-rates. • The creation of a digital twin of the physical Split Hopkinson Test bench. • To demonstrate that there can be distortions of the transmitted measuring signal. This work deals with the high strain-rate characterization of paper under uniaxial tension using a Split Hopkinson test bench. An aluminum bar system featuring a highly sensitive hollow transmission bar was used. Paper tests were performed in a strain-rate range between approximately 60 s−1 and 210 s−1. The experimental tests showed that the breaking strength appears to decrease with increasing strain-rate. To verify these results, a digital twin of both the paper specimen and the entire test rig was created in an explicit Finite Element method environment. The numerical model was then used to perform a parameter study with different types of transmission bars. It was shown that the system is quite sensitive to additional masses caused by the specimen fixtures, as well as to drastic reductions in the cross section of the transmission bar. As a result, the transmitted measuring signal can be distorted and may need to be corrected using the digital twin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular-level light-emitting origins were strategically imparted to paper. • The morphology of AIE self-assembly can be adjusted on demand. • AFP-FP exhibited high selectivity, sensitivity and repeatable recognition of NH 3. • AFP-FP integrated with smartphone realized the visual food spoilage monitoring. Biogenic amines containing NH 3 are important indicators for conducting full-scale appraisal of food spoilage and disease diagnosis. However, the currently-used detection methods of NH 3 have several limitations such as time-consuming high cost, and inability to provide visual real-time monitoring. Therefore, researchers have attempted to explore strategies for quantitative real-time monitoring of NH 3 for food spoilage has attracted widespread attentions. Herein, we developed sustainable, fast response, hypersensitized, user-friendly and molecular-level light-emitting biomass-based materials (AFP-FP) containing on-demand nanostructured brain-cells-inspired aggregation-induced-emission (AIE) self-assembles for real-time visual monitoring of seafood spoilage. The 2-hydroxy-5-methyl-isophthalaldehyde-based AIE probe (AFP) was synthesized using a simple "one-step" route. AFP-FP exhibited high selectivity, sensitivity, repeatable and quantitative recognition (y = 7.292×103x + 7.621×104, R = 0.990) of NH 3 with a low detection limit (246 ppb) and fast response (<1 s). Furthermore, we integrated AFP-FP into a user-friendly smartphone color recognition app, enabling its practical application in visual, real-time daylight monitoring of food spoilage. [ABSTRACT FROM AUTHOR]

[Display omitted] • An visual distance-based paper analytical device has been developed for on-site detection of Pb(II). • Pb(II) can inhibit the catalytic activity of G4/hemin DNAzyme induced by K+. • The biosensor can sensitively detect Pb(II) with a lowest detection limit of 1 nM. • The biosensor can be applied to detect Pb(II) in real samples. A simple, inexpensive, fast, and visual distance-based paper analytical device has been developed for on-site detection of Pb(II). Pb(II) can inhibit the catalytic activity of G-quadruplex/hemin (G4/hemin) DNAzyme induced by K+, which catalyzes 3,3,5,5-tetramethyl benzidine (TMB) immobilized on paper to produce a visible blue band. The factors affecting Pb(II) detection have been optimized with PS concentration of 3 μM, K+ concentration of 10 mM, and hemin concentration of 10 μM, as well as the straight channel width of 2.0 mm. It can be well found that the formed length correlates with the concentration of Pb(II) with a linear detection range of 0.02 μM − 50 μM. A fitting linear equation of Y = 20.793–5.391Log C (R2 = 0.9788) can be obtained with a lowest detection limit of 1 nM. Additionally, the method is capable of selectively detecting Pb(II) and works well for Pb(II) detection in real samples. Overall, the visual distance-based paper analytical device offers an ideal platform for on-site detection of heavy metal ions, especially in resource-limited areas. [ABSTRACT FROM AUTHOR]

Deoxyribonuclease I (DNase I) is a biomarker which has important applications in various biological processes. Thus, it is highly important to develop a user-friendly method for the detection of DNase I. Here, we present a paper-based distance sensor for the rapid detection of DNase I based on changes in the viscosity of DNA mucus. The viscosity of DNA mucus varies with different concentrations of DNase I, showing different water flow lengths on the pH test papers, this makes the quantification of DNase I possible. This method has a wide linear range (0.01–10 U/mL), excellent sensitivity, remarkable specificity and excellent reproducibility. The detection limit reaches 0.003 U/mL. Additionally, it can be well applied to detection of DNase I inhibitors, assay of DNase I in human serum and quality evaluation of nucleic acid scavengers. In general, this study offers a brief, convenient, label-free, and economical method to construct paper-based distance sensors using DNA mucus, which is very promising in the detection of DNase I in various applications. [Display omitted] • The paper-based sensor detects DNase I by distance signal. • The new method for detecting DNase I based on viscosity changes. • The detection limit for DNase I is 0.003 U/mL. • The sensor shows excellent specificity, remarkable practicality and portability. [ABSTRACT FROM AUTHOR]

An effective strategy was demonstrated to design an electromagnetic interference (EMI) shielding paper via a facile surface treatment on paper. TEMPO-oxidized cellulose nanofibers (TOCN) were first integrated with Ti 3 C 2 T x MXene, and subsequently cast onto a filter paper with cationic guar gum (CGG) in a sequential way. TOCN and CGG generated a self-assembling hydrogel and formed a MXene-containing hydrogel film on top of the filter paper. The hydrogel film enhanced the tensile strength (9.49 MPa) of composite paper, and resulted in a 17 % increase as compared to the control. The composite paper containing 80 mg MXene (namely, 2.07 mg·cm−2) showed a conductivity of 3843 S·m−1 and EMI shielding effectiveness (EMI SE) of 49.37 dB. Furthermore, the 2-layer assembled TC-M 80 hydrogel composite paper achieved an EMI SE of 73.99 dB. Importantly, this composite paper showed higher EMI SE and lower thickness than a lot of reported materials. The presence of TOCN and CGG also protected MXene against several solvents and the incorporation of polydimethylsiloxane (PDMS) further improved the durability of the composite paper. This work provides a novel and simple strategy to design robust, ultrathin and flexible EMI shielding materials, and it might also inspire other work in paper-based functional materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • For the first time the root cause for paper curl developing over days and weeks is described. • The curl of the paper sheets is caused by migration of co-solvents (e.g., glycerol) from the inkjet ink. • A 2D-laser scanner is utilized to investigate short- and long-term paper curl. • Glycerol migration in paper sheets is monitored using a combination of sheet splitting and subsequent HPLC analysis. The dimensional stability of paper during printing is crucial for ensuring production quality and runnability. However, inkjet printing faces inherent challenges due to the hygroscopic nature of paper and the use of water-based inks. Despite freshly printed sheets are flat, a considerable development of paper curl is often observed during storage. In this study, we establish the link between the migration of ink co-solvents and the long-term curl development of printed paper. A4 paper sheets were sprayed with a water-glycerol model ink and changes in the sheet's curvature were monitored using a 2D-laser sensor. We also investigated glycerol migration by splitting the sheets into layers and determining the glycerol distribution using high-performance liquid chromatography. Our results demonstrate the development of curl during storage as well as glycerol migration in thickness direction of the sheet, both on a comparable timescale. We thus propose that long term curl in inkjet printing can be caused by z-directional migration of the co-solvent (glycerol) over time. This study enhances understanding of the physical mechanisms that drive the long-term curl phenomenon in inkjet-printed sheets. The results can be used to optimize printing processes, allowing for the production of higher quality printed products with greater dimensional stability. [ABSTRACT FROM AUTHOR]

Limnocharis flava is a noxious aquatic weed that poses a threat to paddy cultivation. The high cellulose and low lignin contents in this plant make it a potential raw material for papermaking. Against this backdrop, this study was taken up to develop Limnocharis flava (LF) based sheets containing natural fibres from Banana (B), Pineapple (P), and Rice Straw (RS) as reinforcing agents. The influence of carboxymethyl cellulose (CMC) as a binder on the LF-based sheets was also studied. To enhance the mechanical and moisture resistance properties, a chitosan coating was provided to the sheets. Analytical tests for mechanical properties, water barrier properties, functional groups, structure and microstructure, thermal properties and biodegradability were performed. Among the samples, LF + B showed the highest tensile strength (34.86 Mpa) and bursting strength (13.055 kg/cm2), while LF + R had higher puncture and tearing strengths. Chitosan coating was found to enhance the sheets and improve the water barrier properties mechanically. The contact angle of LF + B increased from 91.6° to 110.65°, while the water vapour transmission rate of LF reduced from 532.18 to 404.47 on providing chitosan coating. The significant interactions of reinforcing agents were confirmed by the results of FTIR and that of the coating by the SEM micrographs. The LF-based sheets were also found to have decent thermal stability. The high value of the crystallinity index in LF + R samples supported their remarkable mechanical properties. This study proclaims the notable suitability of Limnocharis flava in manufacturing paper for packaging applications. [Display omitted] • Limnocharis flava based composite sheets were developed for packaging applications • Bio coating using chitosan was applied to enhance quality parameters • The developed material had impressive mechanical and water barrier properties • The developed material was used for cardamom packaging alternative to wood pulp /plastic packaging [ABSTRACT FROM AUTHOR]

Kraft method, the most widely used method in pulp production, causes to various environmental problems. Therefore, environmentally friendly pulp production methods have been investigated. In recent years, environmentally friendly deep eutectic solvents (DESs) as cooking liquor have been investigated. In this study, the possibilities of using a ternary DES (TDES) in pulp production from Scots pine (Pinus sylvestris L.) chips were investigated. TDES constituents were choline chloride (ChCl), lactic acid (LA), and glycerol (G). The effects of cooking temperature (145 °C and 155 °C) and cooking time (3 h, 3.5 h, and 4 h) on pulp and paper properties in TDES pulping were investigated. For comparison, kraft pulp from Scots pine was produced with conditions of 18% active alkali, 25% sulfidity, 155 °C cooking temperature, and 3.5 h cooking time. The highest lignin removal was obtained from TDES3 pulping conditions (155 °C and 4 h) with 76.0%. Lignin removal in the kraft pulp was 67.8%. TDES pulps were more quickly beaten to the target freeness level of 25°SR (the times for TDES3 and kraft pulps were 90 sec and 1350 sec, respectively.). Crystallinity index (CrI) values of kraft pulp and TDES3 pulp were 70.7% and 68.0%, respectively. TDES6 pulp had the highest pulp strength. But, the strength properties of all TDES pulps had lower than kraft pulp. TDES pulping can be a greener alternative to kraft pulping. • The pulp production using TDES from Scots pine was accomplished successfully. • The longer cooking time at 155 °C caused significant changes in fiber morphology. • Some properties of TDES pulps were comparable to those of the kraft pulps. • TDES pulping conditions had a significant effect on the pulp and paper properties. • TDES pulps more quickly reached to target freeness level. [ABSTRACT FROM AUTHOR]

The scientific literature supports the hypothesis of a disadvantage in students' performances when learning tasks are conducted in the digital mode in comparison to the paper one. Some studies suggest the need of investigating the role of individual cognitive functioning in digital reading and writing with special attention to those cognitive processes, such as Executive Functions (EF), which are acknowledged to control and affect learning and school adaptation. The present study aimed to: 1) investigate the differences in performances between paper and digital modalities in text reading and text writing in primary grade students; 2) analyse whether EF predict performances in paper and digital modalities; 3) explore whether any differences between paper and digital text comprehension or writing can be differently explained by EF depending on the children's learning performances. 175 typically developing Grades 3–5 students performed text comprehension and text writing tasks on computer and on paper and were assessed with EF tasks tapping inhibitory control, working memory and cognitive flexibility. The results showed no performance differences between digital and paper tasks at the group level apart from a higher text length in the digital than paper mode. However, children with low performances at the comprehension and writing tasks benefited more from the digital than the paper mode, in comparison to high performers that showed the opposite pattern. Additionally, low performers scored worse than high performers in most of the EF tasks. Lastly, working memory explained the digital-paper difference in text comprehension among low comprehenders as well as cognitive flexibility explained the difference in level of narrative complexity and number of words among low writers. The results suggest the benefit of the digital mode for low readers and writers and highlight the role of the main components of EF in reading and writing in both paper and digital modes in primary school. • Poor primary readers and writers benefit more from the digital mode • Poor primary readers and writers show low Executive Functions • Executive Functions predict both digital and paper reading and writing • Executive Functions support the digital-paper differences [ABSTRACT FROM AUTHOR]

The high demand for flexible electroconductive elements, such as organic coatings, is associated with the development of IoT devices, wearable health monitoring devices, and similar devices. To meet cost and environmental standards, the ideal coating should use the richness of nature, be biodegradable, and be water soluble to avoid the use of harmful organic solvents. All of these criteria are met by the composite coating consisting of sodium lignosulfonate (SLS) and multiwall carbon nanotubes (MWCNTs). Furthermore, the SLS/CNT coating on paper substrates is highly electroconductive, hydrophobic, and resistant to annealing, high humidity, bending, and scratching. The electrical conductivity of the SLS/CNT coating varies depending on the substrate used, but it is highly conductive and resistant on all substrates tested. Most importantly, due to the use of abundant and mass produced and cheap materials, the price of a coating containing 77 wt% SLS and 23 wt% CNT, with a sheet resistance of 113 Ω/sq is estimated to be around 2.05 EUR/m2. This coating can be especially beneficial for large-scale applications, such as heating films. [Display omitted] • SLS is an affordable and readily available stabilizer for CNT dispersion in water. • SLS/CNT creates a highly conductive coating on cellulose substrates. • The SLS/CNT coating on paper has potential applications as cost-effective sensors or heaters. • The conductivity of the coating is influenced by the properties of the substrate. [ABSTRACT FROM AUTHOR]

Dissolved sulfide tends to species transformation and loss upon leaving the matrix, thus the development of a practical on-site determination of sulfide is crucial for environmental monitoring and human health. In this work, a novel paper-based ratiometric fluorescence sensor was developed for the field analysis of sulfide, which system was constructed by the inner filter effect (IFE) of CdS quantum dots (QDs) toward carbon dots (C-dots). Instead of an aqueous phase system, the conversion of sulfide to its hydride would induce the in-situ formation of CdS QDs on the paper, which acted as an energy acceptor to quench the emission of C-dots, leading to a variation of ratiometric fluorescence from blue to yellow with the increasing concentration of sulfide. Moreover, we proposed a smartphone-based fluorescence capture device integrated with a programmed Python program, accomplishing both color recognition and accurate detection of sulfide. Under the optimal condition, this ratiometric fluorescence sensor allowed for the on-site analysis of sulfide with a limit of detection of 0.05 μM. The accuracy of the sensor was validated via the successful field analysis of environmental water samples with satisfactory recoveries. Compared to other fluorescence methods used for sulfide analysis, this developed system retains the advantages of label-free, low-cost, ease of operation, and miniaturization, showing great potential for the measurement of sulfide on-site, as well as environmental monitoring. [Display omitted] • A paper-based fluorescence sensor was developed for the field analysis of sulfide. • Sulfide induced the IFE between C-dots and CdS QDs and caused fluorescence change. • The portable device for sulfide analysis is low-cost and easy to operate. • The developed system shows great potential for the measurement of sulfide on-site. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonication improves the absorption of metallic salt in the paper. • Ultrasound catalyzes the synthesis of metallic nanoparticles. • A longer sonication time during salt absorption increases the number of nanoparticles obtained. • Nanoparticles obtained by sonochemistry are an easy and reproducible method to modify paper. This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO 3 and CuSO 4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method. [ABSTRACT FROM AUTHOR]

Building walls are responsible for the highest share of environmental impact among other building elements and the whole building envelope is linked to nearly half of the energy embodied in the building. One of the sustainable materials that may be applied in building envelopes to reduce their impact is paper, e.g. corrugated cardboard or paperboard. Although environmental qualities are considered the key advantage of paper, the environmental properties of previously proposed designs were rarely assessed nor compared to conventional building envelopes. Therefore, the aim of this research is to analyse the performance and environmental impact of selected paper-based envelopes, compare them with conventional alternatives based on steel and timber, and indicate key factors influencing their environmental performance. Moreover, the article proposes two original paper-based envelopes with favourable environmental characteristics. The environmental analysis was conducted via Life Cycle Assessment, using the midpoint CML method and the endpoint ReCiPe method with a single indicator. LCA was based on the Ecoinvent 3.8 database and supplemented with sensitivity analysis. LCA results were compared with performance assessment. It has been shown, that replacement of conventional envelopes with paper-based ones, especially in buildings with a limited lifespan, may reduce their environmental impact and the amount of waste generated. In conclusion, a series of recommendations for sustainable paper-based envelope designs are formulated. [Display omitted] • Paper-based building envelopes may reduce buildings' environmental impact. • A combination of LCA and performance analyses may be used for envelopes' assessment. • Envelopes with embedded structural elements are preferable to sandwich structures. • Durable yet sustainable claddings are crucial for paper-based envelopes' performance. [ABSTRACT FROM AUTHOR]

Point-of-care testing (POCT) technology is urgently required owing to the prevalence of the Internet of Things and portable electronics. In light of the attractive properties of low background and high sensitivity caused by the complete separation of excitation source and detection signal, the paper-based photoelectrochemical (PEC) sensors, featured with fast in analysis, disposable and environmental-friendly have become one of the most promising strategies in POCT. Therefore, in this review, the latest advances and principal issues in the design and fabrication of portable paper-based PEC sensors for POCT are systematically discussed. Primarily, the flexible electronic devices that can be constructed by paper and the reasons why they can be used in PEC sensors are expounded. Afterwards, the photosensitive materials involved in paper-based PEC sensor and the signal amplification strategies are emphatically introduced. Subsequently, the application of paper-based PEC sensors in medical diagnosis, environmental monitoring and food safety are further discussed. Finally, the main opportunities and challenges of paper-based PEC sensing platforms for POCT are briefly summarized. It provides a distinct perspective for researchers to construct paper-based PEC sensors with portable and cost-effective, hoping to enlighten the fast development of POCT soon after, as well as benefit human society. • The merits of functionalized paper for PEC sensor are introduced. • Photosensitive material and signal amplification strategy of paper-based PEC sensor are discussed. • The application of paper-based PEC sensor in the field of POCT is highlighted. • The limitations and challenges of paper-based PEC sensor are summarized. [ABSTRACT FROM AUTHOR]

In the past few years, point-of-care testing (POCT) technology has crossed the boundaries of laboratory determination and entered the stage of practical applications. Herein, the latest advances and principal issues in the design and fabrication of paper-based bipolar electrode electrochemiluminescence (BPE-ECL) sensors, which are widely used in the POCT field, are highlighted. After introducing the attractive physical and chemical properties of cellulose paper, various approaches aimed at enhancing the functions of the paper, and their underlying principles are described. The materials typically employed for fabricating paper-based BPE are also discussed in detail. Subsequently, the universal method of enhancing BPE-ECL signal and improving detection accuracy is put forward, and the ECL detector widely used is introduced. Furthermore, the application of paper-based BPE-ECL sensors in biomedical, food, environmental and other fields are displayed. Finally, future opportunities and the remaining challenges are analyzed. It is expected that more design concepts and working principles for paper-based BPE-ECL sensors will be developed in the near future, paving the way for the development and application of paper-based BPE-ECL sensors in the POCT field and providing certain guarantee for the development of human health. • Preparation and application prospect of paper-based BPE-ECL sensor are discussed. • Approaches to boost functionalization of paper and existing limitations are described. • Fabricating BPE from classical electrode materials are introduced exhaustively. • Strategies of enhancing ECL signal to improve device sensitivity are displayed. [ABSTRACT FROM AUTHOR]

Nanogenerators and self-powered nanosensors have shown the potential to power low-consumption electronics and human-machine interfaces, but their practical implementation requires reliable, environmentally friendly and scalable processes for manufacturing and processing. Furthermore, the emerging flexible and wearable electronics technology demands direct fabrication onto innovative substrates such as paper and plastics typically incompatible with high process temperatures. This article presents a plasma synthesis approach for the fabrication of piezoelectric nanogenerators (PENGs) and self-powered sensors on paper substrates. Polycrystalline ZnO nanocolumnar thin films are deposited by plasma-enhanced chemical vapour deposition on common paper supports using a microwave electron cyclotron resonance reactor working at room temperature yielding high growth rates and low structural and interfacial stresses. Applying Kinetic Monte Carlo simulation, we elucidate the basic shadowing mechanism behind the characteristic microstructure and porosity of the ZnO thin films, relating them to an enhanced piezoelectric response to periodic and random inputs. The piezoelectric devices are assembled by embedding the ZnO films in polymethylmethacrylate (PMMA) and using Au thin layers as electrodes in two different configurations, namely laterally and vertically contacted devices. We present the response of the laterally connected devices as a force sensor for low-frequency events with different answers to the applied force depending on the impedance circuit, i.e. load values range, a behaviour that is theoretically analyzed. The characterization of the vertical devices in cantilever-like mode reaches instantaneous power densities of 80 nW/cm2 with a mean power output of 20 nW/cm2. Besides, we analyze their actual-scenario performance by activation with a fan and handwriting. Overall, this work demonstrates the advantages of implementing plasma deposition for piezoelectric films to develop robust, flexible, stretchable, and enhanced-performance nanogenerators and self-powered piezoelectric sensors compatible with inexpensive and recyclable supports. [Display omitted] • Piezoelectric devices directly fabricated on common paper by plasma scalable procedures. • Porous and low residual stress ZnO with c-axis oriented in a fan-like pattern for multidirectional activation. • Energy scavenging of random environmental (airflow) and human (handwriting) stimulus. • Force sensor adjustable response proportional to the applied force or its first derivative. • Highly robust piezoelectric sensors and nanogenerators on paper supports. [ABSTRACT FROM AUTHOR]

• Recent advances in paper/thread-based zone and capillary electrophoresis techniques. • Various sample pretreatment methods using electrophoresis on wicking substrates. • Review of unmodified and modified microfluidic paper/threat -based chromatography. • Application of paper/threat -based chromatography in blood separation. Paper and thread are widely used as the substrates for fabricating low-cost, disposable, and portable microfluidic analytical devices used in clinical, environmental, and food safety monitoring. Concerning separation methods including chromatography and electrophoresis, these substrates provide unique platforms for developing portable devices. This review focuses on summarizing recent research on the miniaturization of the separation techniques using paper and thread. Preconcentration, purification, desalination, and separation of various analytes are achievable using electrophoresis and chromatography methods integrated with modified or unmodified paper/thread wicking channels. A variety of 2D and 3D designs of paper/thread platforms for zone electrophoresis, capillary electrophoresis, and modified/unmodified chromatography are discussed with emphasis on their limitation and improvements. The current progress in the signal amplification strategies such as isoelectric focusing, isotachophoresis, ion concentration polarization, isoelectric focusing, and stacking methods in paper-based devices are reviewed. Different strategies for chromatographic separations based on paper/thread will be explained. The separation of target species from complex samples and their determination by integration with other analytical methods like spectroscopy and electrochemistry are well-listed. Furthermore, the innovations for plasma and cell separation from blood as an important human biofluid are presented, and the related paper/thread modification methods are explored. [ABSTRACT FROM AUTHOR]

Globe Thistles-Like NiCo 2 S 4 and rGO grow on flexible paper for the detection of H 2 O 2. [Display omitted] • To paper as the basement, successfully developed a low cost and biodegradable flexible electrochemical sensor electrode materials. • NiCo 2 S 4 microspheres with unique globe thistles-like structure was prepared for the first time. • The NiCo 2 S 4 /rGO/FP electrode has high sensitivity, low LOD, and wide linear range. The Globe Thistles-Like (GTL) NiCo 2 S 4 nanostructures were supported on reduced graphene oxide modified filter paper (FP). The prepared GTL NiCo 2 S 4 /rGO/FP is investigated as a disposable and flexible electrode for the electrochemical detection of H 2 O 2 in alkaline media. Owing to the rich redox active sites, the synergistic effect between Co3+ and Ni2+, and the rapid electron transportation of substituting sulfur (S) for oxygen (O) in NiCo 2 O 4 , the GTL NiCo 2 S 4 /rGO/FP exhibits considerable enzyme-free H 2 O 2 sensing performance with wide linear H 2 O 2 ranging from 38.8 to 37306.8 μM, high sensitivity of 2.4326 mA mM−1 cm−2, and low detection limit of 0.08 μM. The GTL NiCo 2 S 4 /rGO/FP electrode has stable sensing performance and is highly selective toward analyte for physiological interfering species. The excellent electrochemical performance of GTL NiCo 2 S 4 /rGO/FP composite is attributed to the GTL structure of NiCo 2 S 4. By studying the hydrothermal reaction time, electrochemical active surface area, and hydrophilic-hydrophobic surfaces of GTL NiCo 2 S 4 /rGO/FP composite, the relationship between the microstructure and sensing performance of the composite was elucidated. Surely this study opens up new possibilities for the application of low-cost, biodegradable flexible electrode materials in wearable sensors in the near future. [ABSTRACT FROM AUTHOR]

• Preparation of dual functional humidity humidity-sensitive paper using sustainable nanoclay and beeswax. • Increment of actuation degree up to 110° (30 %RH) from 40° (90 %RH). • Able to detect humidity from changes in electrical resistances (150-700kΩ). A highly humidity-responsive paper can detect moisture or OH-attached molecules at the sub-micron or nano level range. Applying hydrophilic nanoclay as an active material for water sensing would reduce the fabrication cost while remaining environmentally friendly. In this communication, we report the preparation of a nanoclay-inspired dual-responsive smart film that can signal humidity levels from mechanical and electrical responses. The paper will bend as the nanoclay layer swells whereas the resulting bending strain will trigger the electrical resistance changes in the hydrophobic electrically conductive graphite-beeswax layer. [ABSTRACT FROM AUTHOR]

Understanding water absorbency in paper is challenging as fibre swelling and out-of-plane deformation occur simultaneously during liquid imbibition. Liquid absorption is commonly accessed by gravimetric tests, which provides limited information on the local spatial and temporal distribution of fluid in the substrate. In this work, we developed iron tracers to map liquid imbibition in paper by in situ precipitation of iron oxide nanoparticles during passage of the wetting front. The iron oxide tracers were found to be robustly attached to the cellulosic fibres. After liquid absorption tests, absorbency was investigated by mapping the distribution of iron in 3D using X-ray micro-computed tomography (μCT) and in 2D using energy-dispersive X-ray spectroscopy. We demonstrate a difference in tracer distribution between the wetting front and the fully saturated region supporting that imbibition proceeds in two phases, i.e. liquid percolation through the cell wall initially prior to filling of the external pore spaces. Critically, we demonstrate that these iron tracers enhance image contrast and allow for new imaging modalities in μCT for fibre networks. [Display omitted] [ABSTRACT FROM AUTHOR]

Synthetic cannabinoids (SC) are extremely prevalent within the prison system and cause problems for prisoners, law enforcement and health services. SC are often soaked into paper then posted into prisons therefore one of the aims of this research is to collaborate with Rapiscan Systems Ltd. and local prisons in England to measure the effectiveness of trace detection methods for the indication of SC in prison post using the Itemiser 3E®. To ensure compounds did not go undetected, samples with Ion Trap Mobility Spectrometry™ peaks indicative of synthetic cannabinoids on the Itemiser 3E® were analysed using Gas Chromatography-Mass Spectrometry, Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy to identify chemical characteristics which allowed comparison to reference spectra. Sample data spanning three years from one prison's Itemiser 3E® were collated to identify trends in drug prevalence and the influence of library updates. To date, the method has identified four compounds: 5F‐MDMB‐PICA, MMB-4en-PICA, 4F‐MDMB‐BUTINACA and MDMB-4en-PINACA on prison post which were not already included on, or needed confirmatory analysis to update, the Itemiser 3E® library. As a result, the libraries on prison Itemiser 3E®s have been updated to ensure future detection of such compounds. Trends and influences from the processed Itemiser 3E® data were also reported back to the West Midlands Prison Group. This research directly benefitted both the West Midlands Prison Group and Rapiscan Systems Ltd. and it is anticipated that the continuation of this research could be expanded to a national scale. • Prisons submitted samples for confirmatory analysis after screening by Itemiser 3E®. • GC-MS, LC-MS and NMR identified synthetic cannabinoids in eight of the 47 samples. • 5F‐MDMB‐PICA, MMB-4en-PICA, 4F‐MDMB‐BUTINACA and MDMB-4en-PINACA were identified. • Confirmatory analysis aided the generation of Itemiser 3E® library definitions. • This demonstrates the importance of the screening, confirmation and feedback cycle. [ABSTRACT FROM AUTHOR]