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Excessive copper (Cu2+) causes adverse effects on human health and the ecological environment. Traditional methods for detecting Cu2+ have drawbacks such as high detection costs, complex operating conditions, and being time consuming. Therefore, there is an urgent need to develop simple detection methods to better meet specific health and environment quality needs. In this work, a paper-based fluorescence sensor was prepared (herein referred to as the as-prepared method) by immersing filter paper in aqueous polyethyleneimine (PEI) solution, and its potential use in Cu2+ detection was investigated. The results showed that the as-prepared paper samples, with fluorescence properties obtained by aggregation-induced luminescence of PEI, have selective recognition of Cu2+ based on the internal filtration effect, and the lowest detection limit is 0.03 μM. In addition, the relative error of this method is in the range of 1.80~2.23%, which is relatively comparable to the national standard method (0.63~630 μM), demonstrating high accuracy. Therefore, paper-based sensors with a simple preparation method have potential applications in the detection of Cu2+ in water. [ABSTRACT FROM AUTHOR]

Background: As the demand for digital dentistry constantly increases, digital devices are gradually replacing conventional methods of recording occlusal contacts. The study aimed to assess the inter-rater reliability of occlusal contact point detection using 40 μm articulating paper, Medit i700, and OccluSense and to compare the distribution of occlusal contacts using the articulating paper and intraoral scanner. Material and Methods: The study included 25 participants aged 20 to 30 (13 women and 12 men). Photographs of contact points were taken and marked in maximum intercuspal position (MIP), in protrusive and laterotrusive movements, on working and non-working sides using 40 μm articulating paper and digital devices. The Cohen's Kappa coefficient assessed the inter-rater reliability. The Wilcoxon signed-rank test was used to compare dependent groups, articulating paper, and Medit i700. Results: The Cohen's Kappa index showed that almost perfect agreement was achieved with 40 μm articulating paper. Compared to Medit i700, the 40 μm articulating paper showed an increased mean number of contacts per tooth, except for the third molars. Conclusions: The 40 μm articulating paper has detected more overall contacts than the digital devices, particularly in the posterior areas. An ideal method for registering occlusal contacts has not been established yet. [ABSTRACT FROM AUTHOR]

Simple Summary: This study emphasizes the significance of appropriate air-drying times in toxicity bioassays to accurately establish sublethal concentrations and discriminating concentrations for resistance detection in mosquitoes to a highly volatile pyrethroid, namely, transfluthrin. The high-throughput screening system toxicity bioassay study demonstrated consistent dose-dependent responses in susceptible mosquito populations. Our findings emphasize the importance of accurate susceptibility testing to facilitate early resistance detection. The air-drying duration significantly affected the efficacy of transfluthrin: after drying for 24 h, the concentration needed to achieve the same level of efficacy was 2.8 times higher compared to the concentration needed after 1 h of drying. This is the first study to evaluate spatial repellents using a high-throughput screening system toxicity bioassay, yielding precise sublethal concentrations and discriminating concentrations for varying air-drying times of transfluthrin-treated filter papers. The study underscores the importance of early detection of resistant mosquito populations and emphasizes the need to optimize air-drying durations in toxicity bioassays. Selecting the right concentrations and assessing behavioral responses are crucial for developing effective mosquito control strategies with spatial repellents. This research enhances our understanding of resistance dynamics and provides guidance for practical implementation in vector control programs. Increasing temperature can enhance the geographical spread and behavior of disease vector mosquitoes, exposing vulnerable populations to Aedes-borne viruses and infections. To address this risk, cost-effective and sustained intervention vector control tools are required, such as volatile pyrethroid spatial repellents. This study used a high-throughput screening system toxicity bioassay to determine the discriminating concentrations of transfluthrin-treated filter papers with variable air-drying times exposed to pyrethroid-susceptible Aedes aegypti mosquitoes. At the highest transfluthrin concentration (0.01706%), a significant reduction in mosquito mortality was observed in filter papers air-dried for 24 h compared to those air-dried for 1 h (odds ratio = 0.390, p < 0.001, 95% confidence interval: 0.23–0.66). Conversely, no significant difference in mortality was found between filter papers air-dried for 1 h and those air-dried for 12 h (odds ratio = 0.646, p = 0.107, 95% confidence interval: 0.38–1.10). The discriminating concentration was 2.8-fold higher for transfluthrin-treated filter papers air-dried for 24 h than it was for papers air-dried for 1 h, and it increased 5-fold from 1 h to 336 h of air-drying. These results show that the optimal air-drying period of transfluthrin-treated filter paper is critical, as higher discriminating concentration values may lead to underestimations of insecticide resistance. The instability of transfluthrin-treated papers necessitates the use of the World Health Organization (WHO) bottle bioassay, which is the preferred method for determining mosquito susceptibility to volatile insecticides. [ABSTRACT FROM AUTHOR]

Flexible paper-based materials play a crucial role in the field of flexible electromagnetic shielding due to their thinness and controllable shape. In this study, we employed the wet paper forming technique to prepare carbon fiber paper with a thickness gradient. The electromagnetic shielding performance of the carbon fiber paper varies with the ladder-like thickness distribution. Specifically, an increase in thickness gradient leads to higher reflectance of the carbon fiber paper. Within the X-band frequency range (8.2–12.4 GHz), reflectivity decreases as electromagnetic wave frequency increases, indicating enhanced penetration of electromagnetic waves into the interior of the carbon fiber paper. This enhancement is attributed to an increased fiber content per unit area resulting from a greater thickness gradient, which further enhances reflection loss and promotes internal multiple reflections and scattering effects, leading to increased absorption loss. Notably, at a 5 mm thickness, our carbon fiber paper exhibits an impressive average overall shielding performance, reaching 63.46 dB. Moreover, it exhibits notable air permeability and mechanical properties, thereby assuming a pivotal role in the realm of flexible wearable devices in the foreseeable future. [ABSTRACT FROM AUTHOR]

Nanorod structures exhibit a high surface-to-volume ratio, enhancing the accessibility of electrolyte ions to the electrode surface and providing an abundance of active sites for improved electrochemical sensing performance. In this study, tetragonal α-MnO2 with a large K+-embedded tunnel structure, directly grown on microfibrous carbon paper to form densely packed nanorod arrays, is investigated as an electrocatalytic material for non-enzymatic glucose sensing. The MnO2 nanorods electrode demonstrates outstanding catalytic activity for glucose oxidation, showcasing a high sensitivity of 143.82 µA cm−2 mM−1 within the linear range from 0.01 to 15 mM, with a limit of detection (LOD) of 0.282 mM specifically for glucose molecules. Importantly, the MnO2 nanorods electrode exhibits excellent selectivity towards glucose over ascorbic acid and uric acid, which is crucial for accurate glucose detection in complex samples. For comparison, a gold electrode shows a lower sensitivity of 52.48 µA cm−2 mM−1 within a linear range from 1 to 10 mM. These findings underscore the superior performance of the MnO2 nanorods electrode in both sensitivity and selectivity, offering significant potential for advancing electrochemical sensors and bioanalytical techniques for glucose monitoring in physiological and clinical settings. [ABSTRACT FROM AUTHOR]

Although paper packages are biodegradable, their applications in food packaging are limited due to high affinity for absorbing moisture and the high permeability of gases and liquids with surroundings. Therefore, exploring the use biodegradable coatings such as nanocellulose to improve barrier is a relevant strategy. This study assessed the efficacy of unbleached nanofibrillated cellulose (NFC) as an additive to paper and coatings. Using NFC derived from unbleached eucalyptus pulp, a 5% mass addition to the paper pulp and a 2 mm wet nanocellulose coating to kraft paper handsheets made from pine pulp were investigated. In addition, nanocellulose films of similar thicknesses were appraised. The physical, morphological, mechanical, and thermal characteristics of the resulting papers were assessed. Incorporating NFC notably enhanced the morphology area of the paper by padding its pores, thus increasing its density by up to 48% and improving its water barrier properties by up to 50%. The mechanical strength showed significant enhancements, particularly in bursting and tensile strength with increases of up to 134% and 50%, respectively. Anyhow, the films exhibited lower bursting indices and no improvement in the tearing index. Nonetheless, the thermal stability of the handsheets with NFC coating meets the minimum requirements for food packaging. [ABSTRACT FROM AUTHOR]

Polyethylene-, polyvinylidene chloride-, and per- and polyfluoroalkyl substance-coated paper generate microplastics or fluorochemicals in the environment. Here, we report an approach for the development of oil-resistant papers using an environmentally friendly, fluorine-free, water-dispersible poly(dimethylsiloxane) (PDMS) coating on kraft paper. Carboxylic-functionalized PDMS (PDMS-COOH) was synthesized and subsequently neutralized with ammonium bicarbonate to obtain a waterborne emulsion, which was then coated onto kraft paper. The water resistance of the coated paper was determined via Cobb60 measurements. The Cobb60 value was reduced to 2.70 ± 0.14 g/m2 as compared to 87.6 ± 5.1 g/m2 for uncoated paper, suggesting a remarkable improvement in water resistance. Similarly, oil resistance was found to be 12/12 on the kit test scale versus 0/12 for uncoated paper. In addition, the coated paper retained 70–90% of its inherent mechanical properties, and more importantly, the coated paper was recycled via pulp recovery using a standard protocol with a 91.1% yield. [ABSTRACT FROM AUTHOR]

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size. [ABSTRACT FROM AUTHOR]

The European Community is striving for a sustainable society as suggested by the UN's 2015 sustainability goals. The circular economy in the paper and packaging industry is of particular importance here because it consumes many resources. The paper industry in Germany with a fiber recycling rate of 85% in 2022 is already a pioneer and role model for other industries. All materials should be recyclable. Fiber-based composites/laminates are currently becoming increasingly important. Essential questions are: which collection systems and recycling paths should be used for fiber-based composites/laminates, and where are there currently challenges with recycling? To answer these questions, 58 questionnaires answered by German experts and practitioners in the German paper industry were evaluated. Wet-strength papers, adhesives, plastic coatings and wax dispersions were perceived as a problem by 70% of all respondents, and packaging residues by almost 40%. Additionally, 90% stated that the composition of paper for recycling changes regularly due to legislation, trends and innovations, while 60% attributed this to recent changes in legislation. For at least 80%, virgin fibers from packaging are valuable for paper recycling, but only 15% of respondents stated that virgin fibers compensate for the disadvantages of rejects. Almost 90% expected challenges with fiber-based composites/laminates in the existing paper for recycling processes. Overall, the collection and recycling of fiber-based composites/laminates in conventional paper for recycling collection and the recycling system is not desirable. An integrated collection, sorting and recycling system should be considered, especially because a further increase in fiber-based composites is to be expected. In the end, the design for recycling and following recycling guidelines are the key to the recycling industry in the future. Good recyclability of fiber-based composites/laminates would improve their acceptance by paper recyclers. Their virgin fibers are particularly valuable. The results of our study are relevant to the recycling and fiber industry, standard-setting bodies, regulatory authorities and research. The limitation of this study is that experts from the paper industry were interviewed, but the recyclability of the fiber materials was not analyzed by measurement, and the machine technology of the interviewees could not be examined and evaluated. [ABSTRACT FROM AUTHOR]

This study examined the possibility of using various types of waste paper—used newsprint (NP), used lightweight coated paper (LWC), used office paper (OP), and used corrugated cardboard (CC)—for the removal of anionic dyes, Acid Red 18 (AR18) and Acid Yellow 23 (AY23), and cationic dyes, Basic Violet 10 (BV10) and Basic Red 46 (BR46), from aqueous solutions. The scope of this research included the characterization of sorbents (FTIR, SEM, BET surface area, porosity, pHPZC, effectiveness of water coloration), determination of pH effect on the effectiveness of dye sorption, sorption kinetics (pseudo-first-order model, second-order model, intraparticular diffusion model), and the maximum sorption capacity (Langmuir models and Freundlich model) of the tested sorbents. The use of waste paper materials as sorbents was found to not pose any severe risk of aquatic environment contamination. AR18, AY23, and BV10 sorption intensities were the highest at pH 2, and that of RB46 at pH 6. The waste paper sorbents proved particularly effective in removing cationic dyes, like in the case of, e.g., NP, which had a sorption capacity that reached 38.87 mg/g and 90.82 mg/g towards BV10 and BR46, respectively, and were comparable with that of selected activated carbons (literature data). [ABSTRACT FROM AUTHOR]

In this study, the integration of paper industry waste with high cellulose content into biocomposites of polylactic acid (PLA), a widely used biobased polymer material, was investigated. The PLA/waste biocomposite samples (0–25 wt.%) were manufactured using the extrusion and injection moulding techniques. The mechanical test results showed improvements in terms of tensile properties and a decrease in impact strength as the percentage of residue increased. The melting temperature decreased, and the crystallinity increased in all biocomposites according to the Differential Scanning Calorimetry (DSC) analysis. Water absorption increased proportionally with the percentage of residue, attributed to the higher cellulose content in the biocomposites, determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) fracture analysis demonstrated effective reinforcement–matrix cohesion, supporting the previously observed behaviour of the analysed materials. This work highlights the potential of using waste from the paper industry as reinforcement in PLA matrices, opening new perspectives for sustainable applications in the framework of the manufacture of composite materials. [ABSTRACT FROM AUTHOR]

The lifespan of an electrical transformer, primarily determined by the condition of its solid insulation, is well known under various operating conditions when mineral oil is the coolant in these machines. However, there is a trend toward replacing this oil with biodegradable fluids, especially esters; therefore, an understanding of the ageing of solid insulation with these fluids is essential. Currently available data do not allow for the selection of the best ester among those available on the market, as each study applies different conditions, making it impossible to compare results. Thus, this paper analyses the degradation of Kraft and Thermally Upgraded Kraft papers with the following five most promising commercial esters: sunflower, rapeseed, soybean, palm, and synthetic. The materials underwent accelerated thermal ageing at 130, 150, and 170 °C, and the integrity of the papers was evaluated through their polymerisation degree and the obtaining of the degradation kinetic models. The wide range of materials studied in this work, which were subjected to the same treatments, allows for a comparison of the esters, revealing significant differences in the impact of the alternative fluids. Sunflower, rapeseed, and soybean esters provided the best paper protection, i.e., the degree of polymerisation of Kraft paper in the tests at 150 °C decreased by 71% with these fluids, compared to the 83% reduction with mineral oil, 79% reduction with palm ester, and 75% reduction with synthetic ester. Furthermore, different kinetic models were obtained to predict the degradation; it was concluded that the Emsley model provides the best fit. Additionally, it was found that the behaviour of a dielectric fluid with one type of paper cannot be extrapolated, which is only noticeable in broad-scope studies. [ABSTRACT FROM AUTHOR]

Paper relics, as carrieres of historical civilization's records and inheritance, could be severely acidic and brittle over time. In this study, the multi-functional dispersion of nanometer magnesium oxide (MgO) carried by 3-aminopropyl triethoxysilane-modified bacterial cellulose (KH550-BC) was applied in the impregnation process to repair aged paper, aiming at solving the key problems of anti-acid and strength recovery in the protection of ancient books. The KH550-BC/MgO treatment demonstrated enhanced functional efficacy in repairing aged paper, attributed to the homogeneous and stable distribution of MgO within the nanofibers of BC networks, with minimal impact on the paper's wettability and color. Furthermore, the treatment facilitated the formation of adequate alkali reserves and hydrogen bonding, resulting in superior anti-aging properties in the treated paper during prolonged preservation. Even after 30 days of hygrothermal aging tests, the paper repaired by KH550-BC/MgO was still in a gently alkaline environment (pH was about 7.56), alongside a 32.18% elevation compared to the untreated paper regarding the tear index. The results of this work indicate that KH550-BC/MgO is an effective reinforcement material for improving the long-term restoration of ancient books. [ABSTRACT FROM AUTHOR]

Paper documents are an important carrier of information related to human civilization, with the reinforcement and protection of fragile paper documents being a key aspect of their protection. This research utilized amphoteric polyvinylamine polymer as a paper reinforcement agent, strengthening the Xuan paper commonly used in paper documents. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), solid-state 13C NMR, and other analytical methods were employed to compare the physical properties, micro-morphology, crystallinity, and aging resistance of the paper before and after reinforcement. Research was conducted on the effects of reinforcement, the aging resistance, and the effects on the fiber structure. The results indicate that polyethylenimine has a filling and bridging effect between the paper fibers. After treatment with polyethylenimine, there was a significant improvement in the folding endurance and tensile strength of the paper. Additionally, the paper maintains a good mechanical strength even after undergoing dry heat and humid aging. [ABSTRACT FROM AUTHOR]

In the realm of electrochemical nitrite detection, the potent oxidizing nature of nitrite typically necessitates operation at high detection potentials. However, this study introduces a novel approach to address this challenge by developing a highly sensitive electrochemical sensor with a low reduction detection potential. Specifically, a copper metal nanosheet/carbon paper sensitive electrode (Cu/CP) was fabricated using a one-step electrodeposition method, leveraging the catalytic reduction properties of copper's high occupancy d-orbital. The Cu/CP sensor exhibited remarkable performance in nitrite detection, featuring a low detection potential of −0.05 V vs. Hg/HgO, a wide linear range of 10~1000 μM, an impressive detection limit of 0.079 μM (S/N = 3), and a high sensitivity of 2140 μA mM−1cm−2. These findings underscore the efficacy of electrochemical nitrite detection through catalytic reduction as a means to reduce the operational voltage of the sensor. By showcasing the successful implementation of this strategy, this work sets a valuable precedent for the advancement of electrochemical low-potential nitrite detection methodologies. [ABSTRACT FROM AUTHOR]

Many plant materials in nature have the ability to change their shape to respond to external stimuli, such as humidity or moisture, to ensure their survival or safe seed release. A well-known example for this phenomenon is the pinecone, which is able to open its scales at low humidity due to the specific bilayer structures of the scale. Inspired by this, we developed a novel humidity-driven actuator based on paper. This was realized by the lamination of untreated paper made from eucalyptus fibers to a paper–carboxymethyl cellulose (CMC) composite. As observed, the hygroexpansion of the composite can be easily controlled by the amount of CMC in the impregnated paper sheet, which, thus, controls the morphologic deformation of the paper bilayer. For a more detailed understanding of these novel paper soft robots, we also studied the dynamic water vapor adsorption, polymer distribution and hygroexpansion of the paper–polymer composites. Finally, we applied a geometrically nonlinear finite element model to predict the bending behavior of paper bilayers and compared the results to experimental data. From this, we conclude that due to the complexity of structure of the paper composite, a universal prediction of the hygromorphic behavior is not a trivial matter. [ABSTRACT FROM AUTHOR]

This study investigates the physical, mechanical, and structural characteristics of handmade paper samples derived from cellulose extracted from grass clippings using two distinct methods as follows: (1) alkali treatment and (2) alkali treatment followed by bleaching, coupled with the incorporation of barium sulfate as a mineral filler. Our investigation revealed that the handmade paper samples' densities, moisture contents, and thicknesses varied within the ranges of 0.436 to 0.549 g/cm3, 5.60 to 2.51%, and 0.41 to 0.50 mm, respectively. The tensile strength and folding endurance of the papers produced through alkali treatment with barium sulfate were notably superior to those produced from bleached pulp and barium sulfate. Our analysis indicates that several critical factors, including paper density, thickness, the crystallinity index, and the microfibrillar structure of cellulose, intricately influence the mechanical and strength properties of the samples. Using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques, we identified characteristic cellulose bonds and examined cellulose's crystalline and amorphous phases. Additionally, the crystallinity index of the samples was determined using both the Segal and peak deconvolution methods. Scanning electron microscopy (SEM) micrographs revealed interconnected networks of cellulose fibers with varying thicknesses and lengths, along with incorporated mineral filler within the cellulose fiber structure. Variations in mineral particle retention were attributed to the presence or absence of cellulose microfibrils. These findings contribute to our understanding of the observed strength characteristics of the paper samples and underscore the potential applications of cellulose derived from grass clippings, especially when combined with barium sulfate as a mineral filler in paper production. [ABSTRACT FROM AUTHOR]

In this paper, the aging characterization of a kind of insulating paper modified by magnetron sputtering MgO particles based on a microstrip resonant sensor was presented. Firstly, the modified insulating paper with 0, 15 and 30 min MgO particle sputtering times was prepared by a magnetron sputtering device. After that, the properties of the modified insulating paper with different sputtering times were analyzed through microscopic characterization, infrared spectrum, polymerization degree, dielectric constant, AC breakdown strength and thermal aging experiments. The results show that the dielectric constant of the modified insulating paper decreased obviously, the AC breakdown strength increased and the thermal aging resistance was better after 15 min of sputtering. The overall performance of the modified insulating paper after 30 min of sputtering is reduced due to excessive sputtering. In addition, microstrip resonant sensors are introduced to characterize the thermal aging degree of the modified insulating paper, and two microstrip resonant sensors are prepared: a complementary split ring resonator (CSRR) and an interdigital-capacitor-shaped defected ground structure resonator (IDCS-DGS). The resonance frequency deviation of the modified insulating paper samples after aging was measured by microstrip resonance sensors to show the influence of aging temperature on aging degree. The experimental results show that the test results of the microstrip resonance sensors are in good agreement with the traditional characterization methods and can characterize the various aging stages of the modified insulating paper to a certain extent, which proves the feasibility of the characterization method. [ABSTRACT FROM AUTHOR]

In the field of book heritage, it is important to develop cleaning/disinfecting treatments that can slow down the degradation of paper to prevent evident and irreversible damage. The objectives of the cleaning treatments are to remove external contaminants and oxidation and decomposition products of the paper, but these processes must not modify the unique characteristics of the book heritage resulting in irreversible changes in the structure of the paper. Recently, several innovative cleaning treatments were developed with the aim of being minimally invasive; however, to assess the effect of these treatments on paper, it is necessary to use a diagnostic non-destructive, rapid, and affordable process. In previous work, we used surface scanning Raman spectroscopy to develop a diagnostic protocol able to follow the aging processes of the paper, discriminating between hydrolysis and oxidation. In this paper, we applied this protocol to study the action of different types of treatments (hydrogel and EUV irradiation), evaluating both their effectiveness and impact on paper parameters. The results reported here demonstrate that the developed in operando diagnostic procedure can follow the changes in the paper structure comparing them to the variability due to the intrinsic inhomogeneity of paper, without sample contact in a rapid and effective way. [ABSTRACT FROM AUTHOR]

The pulp and paper industry plays an important role in the global economy and is inextricably linked to human life. Due to its large scale, the production process generates a large amount of wastewater, which poses a major threat to the environment. The sustainable utilization and safe treatment of pulp and paper wastewater can effectively reduce environmental pollution, improve resource utilization efficiency, protect water resources, provide economic benefits for pulp and paper enterprises, and thus promote the green and sustainable development of the pulp and paper industry. Therefore, this study discusses the pollution components of pulp and paper wastewater and their impact on the environment and human health. In this review, we aim to explore the sustainable development of pulp and paper wastewater by summarizing the characteristics of current pulp and paper wastewater, the commonly used treatment methods for pulp and paper wastewater, the application of pulp and paper wastewater recycling, and the future development direction of pulp and paper wastewater. [ABSTRACT FROM AUTHOR]

The pulp and paper industry is under increasing pressure to reduce its energy consumption and carbon footprint. This study examines the feasibility of integrating high-temperature heat pumps (HTHP) into tissue paper production to enhance energy efficiency and decarbonization. Focusing on the energy-intensive drying process, the study uses data from a typical tissue paper mill to simulate and optimize an HTHP system producing four tons per hour of nine-bar saturated steam. It also addresses necessary modifications for HTHP integration applicable across the sector. Various refrigerants were analyzed, achieving a maximum coefficient of performance (COP) of 2.01. Results showed that HTHP can reduce energy consumption and emissions by up to 17% and 40%, respectively, based on the European electricity mix. Although steam production costs increase by 55% compared to fossil fuel-based systems, HTHP is more cost-effective than direct electric resistance heating, which raises costs by 196%. With a CO2 price of EUR 100/t, HTHP offers a 12% cost reduction. However, without public funding, capital expenditures may be unsustainable in many regions, though viable in countries with favorable gas and electricity price differentials. The paper underscores the need for advancements in HTHP technology and cost reductions, emphasizing industry adaptation for seamless HTHP integration. [ABSTRACT FROM AUTHOR]

For a wide range of applications, paper materials require effective protection against the destructive effect of water, which is most effectively realized by superhydrophobic coatings. In recent years, a considerable amount of scientific research has been carried out in this area, focusing particularly on biogenic resources. With this contribution, we go one step further and examine how biogenic materials can be transferred into aqueous dispersions and coated onto paper via existing technologies. With this paper coating, based on a hydrophobic cellulose derivative in combination with a structurally similar wax, thermally regenerable flower-like surface morphologies are obtained via self-assembly, where the hydrophobic cellulose polymer acts as a structural template for the co-crystallization of the wax component. Such hydrophobic structures in the low micrometer range ensure perfectly water-repellent paper surfaces with contact angles > 150° starting from coating weights of 5 g/m2. The dispersion can be successfully applied to a variety of commercially available paper substrates, whereby the effects of different roughness, porosity, and hydrophobicity were investigated. In this context, a certain roughness of the base paper (Sa ~ 1.5–3 µm) was found to be beneficial for achieving the highest possible contact angles. Furthermore, the approach proved to be paper process-compatible, recyclable, and regenerable, whereby the processing temperatures allow the coating properties to be thermally generated in situ. With this work, we demonstrate how biogenic waxes are very well suited for superhydrophobic, regenerative coatings and, importantly, how they can be applied from aqueous coatings, enabling simple transfer into the paper industry. [ABSTRACT FROM AUTHOR]

New biodegradable paper-based films are a hot research topic in the development of green agriculture. In this study, a black paper-based film coated with cooked tung oil with excellent mechanical properties, a hydrophobic surface, high heat transfer and strong weather resistance was prepared by spraying high-pigment carbon black solution on the surface of base paper. The results showed that the surface-solidified oil film had a rough structure produced via the brush coating process using cooked tung oil. The base film of the black paper had a given hydrophobic structure, and the contact angle reached 98.9°. Cooked tung oil permeates into the inside of the paper base, and after curing, it forms a multi-dimensional network film structure. The maximum tensile stress of the black paper base film is about 123% higher than that of the original paper base film. The coloring of carbon black gives the black paper base film a heat conduction effect, and the average heat transfer rate reaches 15.12 °C/s. Cooked tung oil is combined with the paper-based fiber high-toughness layer to form a stable system. The existence of a cured film improves the basic mechanics and hydrophobicity, and the resistance to ultraviolet radiation and hot air is greatly improved. This study provides a feasible scheme for the application of a black paper base film coated with cooked tung oil. [ABSTRACT FROM AUTHOR]

Curl propensity is a critical-to-quality (CTQ) property of paper, as it causes severe problems during printing and other final conversion operations. The main papermaking factor causing the curl phenomenon is the existence of a fiber orientation (FO) gradient across the thickness direction (or ZD), also known as two-sidedness. Therefore, a methodology that characterizes the FO across the ZD is fundamental for papermakers. In this work, we propose and validate an efficient and cost-effective protocol based on sheet splitting and image analysis. Besides assessing the level of FO two-sidedness, the methodology also provides insights into the flow dynamics in the draining zone of the forming section of the paper machine and the drying stresses built into the paper. This information is relevant for monitoring, optimizing, and troubleshooting activities in the paper industry. [ABSTRACT FROM AUTHOR]

Skin-based wearable devices have gained significant attention due to advancements in soft materials and thin-film technologies. Nevertheless, traditional wearable electronics often entail expensive and intricate manufacturing processes and rely on metal-based substrates that are susceptible to corrosion and lack flexibility. In response to these challenges, this paper has emerged with an alternative substrate for wearable electrodes due to its cost-effectiveness and scalability in manufacturing. Paper-based electrodes offer an attractive solution with their inherent properties of high breathability, flexibility, biocompatibility, and tunability. In this study, we introduce carbon nanotube-based paper composites (CPC) electrodes designed for the continuous detection of biopotential signals, such as electrooculography (EOG), electrocardiogram (ECG), and electroencephalogram (EEG). To prevent direct skin contact with carbon nanotubes, we apply various packaging materials, including polydimethylsiloxane (PDMS), Eco-flex, polyimide (PI), and polyurethane (PU). We conduct a comparative analysis of their signal-to-noise ratios in comparison to conventional gel electrodes. Our system demonstrates real-time biopotential monitoring for continuous health tracking, utilizing CPC in conjunction with a portable data acquisition system. The collected data are analyzed to provide accurate heart rates, respiratory rates, and heart rate variability metrics. Additionally, we explore the feasibility using CPC for sleep monitoring by collecting EEG signals. [ABSTRACT FROM AUTHOR]

Although membrane separation technology has been widely used in the treatment of oily wastewater, the complexity and high cost of the membrane preparation, as well as its poor stability, limit its further development. In this study, via the vacuum-assisted suction filtration method, polydopamine (PDA)-coated TiO2 nanoparticles were tightly attached and embedded on both sides of laboratory filter paper (FP). The resultant FP possessed the typical wettability of high hydrophilicity in the air with the water contact angle (WCA) of 28°, superoleophilicity with the oil contact angle (OCA) close to 0°, underwater superoleophobicity with the underwater OCA greater than 150°, and superhydrophobicity under the water with the underoil WCA over 150° for five kinds of organic solvents (carbon tetrachloride, toluene, n-hexane, n-octane, and iso-octane). The separation efficiency of immiscible oil/water, oil-in-water, and water-in-oil emulsions using the modified FP is higher than 99%. After 17 cycles of emulsion separation, a high separation efficiency of 99% was still maintained for the FP, along with good chemical and mechanical stability. In addition, successful separation and purification were also realized for the oil-in-water emulsion that contained the methylene blue (MB) dye, along with the complete degradation of MB in an aqueous solution under UV irradiation. [ABSTRACT FROM AUTHOR]

Waste wood, which has a large amount of cellulose fibers, should be transformed into useful materials for addressing environmental and resource problems. Thus, this study analyzed the application of waste wood as supercapacitor electrode material. First, cellulose fibers were extracted from waste wood and mixed with different contents of graphene nanoplatelets (GnPs) in water. Using a facile filtration method, cellulose papers with GnPs were prepared and converted into carbon papers through carbonization and then to porous activated carbon papers containing GnPs (ACP−GnP) through chemical activation processes. For the morphology of ACP−GnP, activated carbon fibers with abundant pores were formed. The increase in the amount of GnPs attached to the fiber surfaces decreased the number of pores. The Brunauer–Emmett–Teller surface areas and specific capacitance of the ACP−GnP electrodes decreased with an increase in the GnP content. However, the galvanostatic charge–discharge curves of ACPs with higher GnP contents gradually changed into triangular and linear shapes, which are associated with the capacitive performance. For example, ACP with 15 wt% GnP had a low mass transfer resistance and high charge delivery of ions, resulting in the specific capacitance value of 267 Fg−1 owing to micropore and mesopore formation during the activation of carbon paper. [ABSTRACT FROM AUTHOR]

This manuscript offers a concise overview of paper microfluidics, emphasizing its sustainable sensing applications in healthcare, environmental monitoring, and food safety. Researchers have developed innovative sensing platforms for detecting pathogens, pollutants, and contaminants by leveraging the paper's unique properties, such as biodegradability and affordability. These portable, low-cost sensors facilitate rapid diagnostics and on-site analysis, making them invaluable tools for resource-limited settings. This review discusses the fabrication techniques, principles, and applications of paper microfluidics, showcasing its potential to address pressing challenges and enhance human health and environmental sustainability. [ABSTRACT FROM AUTHOR]

Buckypaper (BP), a flexible and porous material, exhibits photovoltaic properties when exposed to light. In this study, we employed radio frequency (RF) sputtering of zinc oxide (ZnO) followed by rapid thermal annealing to enhance the photovoltaic response of BP. We investigated the impact of various sputtering parameters, such as the gas flow ratio of argon to oxygen and deposition time, on the morphology, composition, resistivity, and photovoltaic characteristics of ZnO-modified BP. Additionally, the photovoltaic performance of the samples under different illumination modes and wavelengths was compared. It was found that optimal sputtering conditions—argon to oxygen flow ratio of 1:2, deposition time of 20 min, and power of 100 watts—resulted in a ZnO film thickness of approximately 45 nanometers. After annealing at 400 °C for 10 min, the ZnO-modified BP demonstrated a significant increase in photocurrent and photovoltage, along with a reduction in resistivity, compared to unmodified BP. Moreover, under gradient illumination, the ZnO-modified BP exhibited a photovoltage enhancement of 14.70-fold and a photocurrent increase of 13.86-fold, compared to uniform illumination. Under blue light, it showed a higher photovoltaic response than under other colors. The enhancement in photovoltaic response is attributed to the formation of a Schottky junction between ZnO and BP, an increased carrier concentration gradient, and an expanded light absorption spectrum. Our results validate that ZnO sputtering followed by annealing is an effective method for modifying BP for photovoltaic applications such as solar cells and photodetectors. [ABSTRACT FROM AUTHOR]

This review explores circular economy principles in regard to ethanol production from paper-mill sludge. Environmental sustainability and renewability over fossil fuels make second generation ethanol an attractive energy source in a rapidly growing population and consumption world. Paper sludge (PS), a by-product of the pulp and paper (P&P) industry, can no longer be recycled for paper production and is mainly disposed of in landfills. Therefore, it poses a major environmental challenge. However, it has shown potential as a valuable raw material for ethanol production, along with other pulp and paper products, due to its abundant availability and high cellulosic content. This waste-to-energy (WtE) technology for ethanol production is proposed as an alternative, aligning with circular economy concepts to maximize resource efficiency and minimize waste. This review underlines the circular economy aspects of bioethanol production within paper mill sludge management systems. Circular economy principles applied to ethanol production from PS offer a promising avenue for sustainable biofuel development that not only addresses waste management challenges but also enhances the overall environmental performance of biofuel production. Furthermore, economic benefits are described, highlighting the potential for job creation and community development. [ABSTRACT FROM AUTHOR]

The mechanical properties for paper sheets composited with glucose (Glc), methyl cellulose (MC), and carboxymethyl cellulose (CMC) were investigated. The paper composites were prepared by immersing paper sheets in aqueous solutions of these materials and drying at 100 °C for 30 min. The stress–strain curves for these paper composites were measured by a uniaxial tensile apparatus with a stretching speed of 2 mm/min. The breaking stress and strain for untreated paper were 24 MPa and 0.016, respectively. The paper composites demonstrated stress–strain curves similar to the untreated paper; however, the breaking point largely differed for these composites. The breaking strain and breaking stress for the Glc composite slightly decreased and those for the MC composite gradually increased with the concentration of materials composited. Significant increases in the mechanical properties were observed for the CMC composite. The breaking stress, breaking strain, and breaking energy for the 3 wt.% CMC composite were 2.0-, 3.9-, and 8.0-fold higher than those for untreated paper, respectively. SEM photographs indicated that the CMC penetrated into the inner part of the paper. These results strongly suggest that the mechanical improvement for CMC composites can be understood as an enhancement of the bond strength between the paper fibrils by CMC, which acts as a bonding agent. It was also revealed that the breaking strain, breaking stress, and breaking energy for the CMC composites were at maximum at the first cycle and decreased gradually as the immersion cycles increased. [ABSTRACT FROM AUTHOR]

Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr3+ and Mn2+. The filter paper modified with AuNCs was used to selectively enrich Cr3+ and Mn2+. Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr3+ and Mn2+. Both elements showed linear ranges for concentrations of 10–1000 μg L−1, with limits of detection of 7.5 and 9.0 μg L−1 for Cr3+ and Mn2+, respectively. This method was successfully applied to the determination of Cr3+ and Mn2+ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution. [ABSTRACT FROM AUTHOR]

Oil–paper insulation is the critical insulation element in the modern power system. Under a harsh operating environment, oil–paper insulation will deteriorate gradually, resulting in electrical accidents. Thus, it is important to evaluate and monitor the insulation state of oil–paper insulation. Firstly, this paper introduces the geometric structure and physical components of oil–paper insulation and shows the main reasons and forms of oil–paper insulation's degradation. Then, this paper reviews the existing condition assessment techniques for oil–paper insulation, such as the dissolved gas ratio analysis, aging kinetic model, cellulose–water adsorption isotherm, oil–paper moisture balance curve, and dielectric response technique. Additionally, the advantages and limitations of the above condition assessment techniques are discussed. In particular, this paper highlights the dielectric response technique and introduces its evaluation principle in detail: (1) collecting the dielectric response data, (2) extracting the feature parameters from the collected dielectric response data, and (3) establishing the condition assessment models based on the extracted feature parameters and the machine learning techniques. Finally, two full potential studies are proposed, which research hotspots' oil–paper insulation and the electrical–chemical joint evaluation technique. In summary, this paper concludes the principles, advantages and limitation of the existing condition assessment techniques for oil–paper insulation, and we put forward two potential research avenues. [ABSTRACT FROM AUTHOR]

This work presents the results of paper laser processing. It begins with the selection and examination of the processing parameters, then an examination of the properties of the modified papers and examples of applications of the developed modification method. The properties of laser-modified paper were studied using reflectance spectrophotometry to examine the colour aspects of the modified papers, scanning electron microscopy (SEM) and confocal microscopy for a morphological analysis, and Raman spectroscopy to analyse the papers under the influence of laser light. The influence of laser processing on the wettability of paper and the evenness of unprinted and printed paper was also investigated. The knowledge gained on paper surface modification with laser light was used to propose several applications, such as methods of marking, tactile detection, the controlled removal of optical brightener, ink, and metallised coatings from paper packaging, highlighting the design and aesthetics of paper. The developed laser-assisted method shows a promising, ecological approach to the design of many value-added paper products. [ABSTRACT FROM AUTHOR]

In this study, Al paper and cellulose acetate (CA) filters derived from heated tobacco waste were successfully converted into current collectors and active materials for a supercapacitor device. Typically, heated tobacco contains electrically discontinuous Al paper. First, Al was extracted from the tobacco waste using HCl to produce Lewis acid (AlCl3). This acid was then used in an Al electrodeposition process utilizing the chloroaluminate ionic liquid reaction between the acid and the base (RCl) at room temperature. To enhance the conductivity, a supplementary coating of Al metal was applied to the Al paper through electrodeposition, thus re-establishing the electrical continuity of the discontinuous parts and forming an Al-coated current collector. Moreover, the CA filters were carbonized under a nitrogen atmosphere, yielding carbon precursors (C-CA) for the supercapacitor electrodes. To further enhance the electrochemical performance, nickel oxide (NiO) was incorporated into C-CA, resulting in C-CA@NiO with pseudocapacitance. The specific surface area of CA increased with carbonization and the subsequent incorporation of NiO. The as-synthesized C-CA and C-CA@NiO materials were applied to an Al-coated current collector to obtain C-CA- and C-CA@NiO-based electrodes, exhibiting stable electrochemical behavior in the voltage range of −1.0 to 0 V and 0 to 1.0 V, respectively. An asymmetric supercapacitor (ASC) device was assembled with C-CA@NiO and C-CA as the positive and negative electrodes, respectively. This ASC device demonstrated a high specific capacitance of 40.8 F g−1, while widening the operating voltage window to 2.0 V. The high electrochemical performance of the device is attributed to the successful Al electrodeposition, which facilitates the electrical conductivity and increased porosity of the C-CA@NiO and C-CA materials. To the best of our knowledge, this is a pioneering study in regards to the conversion of biomass waste into current collectors and active materials to fabricate a practical ASC device. Our findings highlight the potential of reusing Al paper and CA filters from heated tobacco waste as essential components of energy storage devices. [ABSTRACT FROM AUTHOR]

Achieving the desired properties of paper such as strength, durability, and printability remains challenging. Paper mills employ calcium carbonate (CaCO3) as a filler to boost paper's brightness, opacity, and printability. However, weak interaction between cellulose fibers and CaCO3 particles creates different issues in the papermaking industry. Therefore, this study explores the influence of various inorganic additives as crosslinkers such as mesoporous SiO2 nanospheres, TiO2 nanoparticles, h-BN nanoflakes, and hydroxylated h-BN nanoflakes (h-BN-OH) on inorganic fillers content in the paper. They were introduced to the paper pulp in the form of a polyethylene glycol (PEG) suspension to enable bonding between the inorganic particles and the paper pulp. Our findings have been revealed based on detailed microscopic and structural analyses, e.g., transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and N2 adsorption/desorption isotherms. Finally, the inorganic fillers (CaCO3 and respective inorganic additives) content was evaluated following ISO 1762:2001 guidelines. Conducted evaluations allowed us to identify the most efficient crosslinker (SiO2 nanoparticles) in terms of inorganic filler retention. Paper sheets modified with SiO2 enhance the retention of the fillers by ~12.1%. Therefore, we believe these findings offer valuable insights for enhancing the papermaking process toward boosting the quality of the resulting paper. [ABSTRACT FROM AUTHOR]

The recyclable paper based on photochromic materials not only reduces the pollution in the paper manufacture process, but also reduces the pollution caused by the use of ink, which receives wide attention. In this paper, a series of phosphomolybdic acid–phosphotungstic acid/ZnO/polyvinylpyrrolidone (PMoA-PWA/ZnO/PVP) hybrid films, which had different ratio of PMoA/PWA, was prepared by the ultrasonic composite method. The results indicated that the hybrid film prepared when the ratio of PMoA to PWA was 3 had the best photochromic performance. In this system, ZnO was the photosensitizer, while PMoA/PWA was the chromophore. The photochromic mechanism of the PMoA-PWA/ZnO/PVP hybrid film was based on the photogenerated electron transfer mechanism. ZnO generated photoelectron under the excitation of visible light, then PMoA and PWA obtained the photoelectron and produced photoreduction reaction to generate heteropolyblue. The visible light photochromic paper was prepared by loaded PMoA-PWA/ZnO/PVP hybrid film (A3) on A4 paper. Application tests showed that the prepared paper had extremely stable, excellent and reversible visible light photochromic properties, whether it was printing patterns or words, and could replace ordinary paper to realize the reuse of paper. [ABSTRACT FROM AUTHOR]

The present study is an evaluation of published papers on machine learning as employed in mastitis research. The aim of this study was the quantitative evaluation of the scientific content and the bibliometric details of these papers. In total, 69 papers were found to combine machine learning in mastitis research and were considered in detail. There was a progressive yearly increase in published papers, which originated from 23 countries (mostly from China or the United States of America). Most original articles (n = 59) referred to work involving cattle, relevant to mastitis in individual animals. Most articles described work related to the development and diagnosis of the infection. Fewer articles described work on the antibiotic resistance of pathogens isolated from cases of mastitis and on the treatment of the infection. In most studies (98.5% of published papers), supervised machine learning models were employed. Most frequently, decision trees and support vector machines were employed in the studies described. 'Machine learning' and 'mastitis' were the most frequently used keywords. The papers were published in 39 journals, with most frequent publications in Computers and Electronics in Agriculture and Journal of Dairy Science. The median number of cited references in the papers was 39 (interquartile range: 31). There were 435 co-authors in the papers (mean: 6.2 per paper, median: 5, min.–max.: 1–93) and 356 individual authors. The median number of citations received by the papers was 4 (min.–max.: 0–70). Most papers (72.5%) were published in open-access mode. This study summarized the characteristics of papers on mastitis and artificial intelligence. Future studies could explore using these methodologies at farm level, and extending them to other animal species, while unsupervised learning techniques might also prove to be useful. [ABSTRACT FROM AUTHOR]

The sustainable use of natural resources is becoming an increasingly important issue today. Stone paper, produced as an alternative to cellulose-based paper from the forest, is rich in minerals and produced without cellulose and water. This study focuses on the behavior of screen-printing ink on two different papers, stone paper and coated sticker paper. Properties such as ink adhesion, rubbing resistance, optical printing ink density, ink consumption, and lightfastness were measured on these surfaces. Solvent- and UV-based inks were used, and printing was carried out on cellulose-based (coated sticker paper) and mineral-based (stone paper) paper layers using three different mesh counts (90, 120, and 140 tpc). The rubbing resistance and lightfastness of the papers were also measured. The present findings revealed that stone paper had the same printability properties as cellulose-based paper. The study concluded that using a 140 tpc mesh with both types of ink results in a high-lightfastness ink layer and lower ink consumption. UV-based inks exhibited high rub resistance across all mesh counts. Additionally, when printing with stone paper, there will be a reduction in ink consumption, thereby achieving cost savings. Based on the present findings, it was concluded that water- and oil-resistant stone paper can be considered an essential alternative in many fields, including the printing industry. [ABSTRACT FROM AUTHOR]

As a significant biomarker during the apoptosis process, cytochrome c (Cyt c) is considered as a critical component in the inherent apoptotic pathway, but the simple and portable detection still remains challengeable. In this work, a portable and visual sensing platform for Cyt c was developed based upon the fluorescence quenching of graphene quantum dots (GQDs), which could be finished within a few seconds. Herein, the absorption spectrum of Cyt c matched the emission spectrum of GQDs well, which could cause the fluorescence quenching of GQDs via the inner filter effect (IFE) in the range of 1–50 μg/mL with the limit of detection as low as 0.1 μg/mL. Furthermore, the intracellular Cyt c was imaged to observe the apoptosis process of cancer cells induced by staurosporine. To achieve the portable and visual detection of Cyt c, GQDs were deposited on the filter paper to form the solid platform, which displayed a gradual fluorescence quenching when different concentrations of Cyt c were present. Compared to the conventional methods, the proposed assay is low-cost, fast, portable, and visual, which will be useful for the investigation of mitochondrial dysfunction and apoptotic cell death. [ABSTRACT FROM AUTHOR]

Though paper is an environmentally friendly alternative to plastic as a packaging material, it lacks antibacterial properties, and some papers have a low resistance to oil or water. In this study, a multifunctional paper-coating material was developed to reduce the use of plastic packaging and enhance paper performance. Natural cellulose nanocrystals (CNCs) with excellent properties were used as the base material for the coating. The CNCs were functionalized into dialdehyde CNCs (DACNCs) through periodate oxidation. The DACNCs were subsequently complexed using erythrosine as a photosensitizer to form an erythrosine–CNC composite (Ery-DACNCs) with photodynamic inactivation. The Ery-DACNCs achieved inactivations above 90% after 30 min of green light irradiation and above 85% after 60 min of white light irradiation (to simulate real-world lighting conditions), indicating photodynamic inactivation effects. The optimal parameters for a layer-by-layer dip coating of kraft paper with Ery-DACNCs were 4.5-wt% Ery-DACNCs and 15 coating layers. Compared to non-coated kraft paper and polyethylene-coated paper, the Ery-DACNC-coated paper exhibited enhanced mechanical properties (an increase of 28% in bursting strength). More than 90% of the bacteria were inactivated after 40 min of green light irradiation, and more than 80% were inactivated after 60 min of white light irradiation. [ABSTRACT FROM AUTHOR]

Flexible paper-based force sensors have garnered significant attention for their important potential applications in healthcare wearables, portable electronics, etc. However, most studies have only used paper as the flexible substrate for sensors, not fully exploiting the potential of paper's micro-nanostructure for sensing. This article proposes a novel approach where paper serves both as the sensitive element and the flexible substrate of force sensors. Under external mechanical forces, the micro-nanostructure of the conductive-treated paper will change, leading to significant changes in the related electrical output and thus enabling sensing. To demonstrate the feasibility and universality of this new method, the article takes paper-based capacitive pressure sensors and paper-based resistive strain sensors as examples, detailing their fabrication processes, constructing sensing principle models based on the micro-nanostructure of paper materials, and testing their main sensing performance. For the capacitive paper-based pressure sensor, it achieves a high sensitivity of 1.623 kPa−1, a fast response time of 240 ms, and a minimum pressure resolution of 4.1 Pa. As for the resistive paper-based strain sensor, it achieves a high sensitivity of 72 and a fast response time of 300 ms. The proposed new method offers advantages such as high sensitivity, simplicity in the fabrication process, environmental friendliness, and cost-effectiveness, providing new insights into the research of flexible force sensors. [ABSTRACT FROM AUTHOR]

Nowadays, the emphasis is on increasing the durability of all products. For this reason, it is also advisable to look into extending the durability of paper products. The main reason for using flax pulp is that flax and cotton pulp are widely used for the production of banknotes due to their higher strength. This paper deals with flax pulp with the addition of nanocellulose, which should further enhance the mechanical properties of the pulp. The tensile strength, breaking length, and tensile energy absorption index were evaluated as the key mechanical properties. At the same time, the effect of the addition of nanocellulose, whether it was added to the pulp mass or applied to the later produced paper as a spray or coating, was tested in comparison to paper without the addition of nanocellulose. The best mechanical properties, i.e., tensile strength, were achieved for the highest addition of 5% of nanocellulose into the pulp, at 24.3 Nm∙g−1, and for the coating application, at 28.7 Nm∙g−1, compared to the flax pulp without the addition, where the tensile strength was 20.5 Nm∙g−1. The results of this research are used for the assessment of nanocellulose as a natural compatible additive to enhance the strength properties of cellulose-based materials. [ABSTRACT FROM AUTHOR]

When designing products with a shorter lifespan, such as packaging and graphic products, sustainability and circular economy are particularly important. The use of an alternative fiber source for papermaking, such as collected biomass from invasive alien plant species (IAPS), is a good example of sustainable natural resource management, where IAPS are seen as a potential source of various new products. The aim of the present study was to analyze the printability of paper made from the IAPS Goldenrod. CMYK prints were made using inkjet digital technology, and their print quality was determined. IAPS Goldenrod paper, with its natural brownish color, low gloss, high voluminosity, high surface roughness and porosity, shows inferior print quality compared to recycled office paper. In order to improve the printability of this paper, surface coating using three different wet film depositions was applied. The results indicate that the smallest coat weight used suppresses the color and inferior properties of IAPS Goldenrod paper efficiently, resulting in similar printability for both the analyzed papers. Only a small difference in print quality between coated IAPS Goldenrod and recycled paper was determined, suggesting that low-value, non-demanding graphic products and packaging could be made from the coated IAPS Goldenrod paper. [ABSTRACT FROM AUTHOR]

The growing demand for environmentally friendly and sustainable materials has led to the invention of innovative solutions aiming to reduce negative impacts on the environment. Mycelium-based green composites (MBCs) have become an alternative to traditional materials due to their biodegradability and various potential uses. Although MBCs are accepted as modern materials, there are concerns related to some of their physical and mechanical properties that might have limitations when they are used. This study investigates the effects of using paper waste to improve MBC properties. In this study, we investigated the physical and mechanical properties of MBCs produced from lignocellulosic materials (corn husk and sawdust) and mushroom mycelia of the genus Lentinus sajor-caju TBRC 6266, with varying amounts of paper waste added. Adding paper waste increases the density of MBCs. Incorporating 20% paper waste into corn husks led to the enhancement of the compression, bending, and impact strength of MBCs by over 20%. Additionally, it was also found that the MBCs produced from corn husk and 10% paper waste could help in reducing the amount of water absorbed into the material. Adding paper waste to sawdust did not improve MBC properties. At the same time, some properties of MBCs, such as low tensile strength and high shrinkage, might need to be further improved in the future to unlock their full potential, for which there are many interesting approaches. Moreover, the research findings presented in this publication provide a wealth of insightful information on the possibility of using paper waste to improve MBC performance and expand their suitability for a range of applications in sustainable packaging materials and various home decorative items. This innovative approach not only promotes the efficient utilization of lignocellulosic biomass but also contributes to the development of environmentally friendly and biodegradable alternatives to traditional materials. [ABSTRACT FROM AUTHOR]

The widespread use of mobile devices and laptops has replaced traditional paper-based learning and the question of how the brain efficiency of digital tablet-based learning differs from that of paper-based learning remains unclear. The purpose of this study was to investigate the difference in brain efficiency for learning between paper-based and digital tablet-based learning by measuring activity in the prefrontal cortex (PFC) using functional near-infrared spectroscopy. Thirty-two subjects were randomly assigned to the paper-based learning or the digital tablet-based learning group. Subjects in each group performed a memory task that required memorizing a three-minute novel (encoding phase) on a paper or digital tablet, followed by a test in which they answered four multiple-choice questions based on the novel's content. To compare both groups, behavioral performance on the test (retrieval phase) and activity in the PFC were measured. As a result, no significant difference in behavioral performance between both groups was observed (p > 0.05). However, the paper-based learning group showed significantly lower activity in the PFC in the encoding phase than the digital tablet-based learning group (p < 0.05) but not in the retrieval phase. The current study demonstrated that brain efficiency in encoding is higher in subjects with paper-based learning than those with digital tablet-based learning. This finding has important implications for education, particularly in terms of the pros and cons of electronic document-based learning. [ABSTRACT FROM AUTHOR]

In recent years, the demand for the protection and restoration of cultural heritage has become increasingly urgent. Particularly for paper-based cultural relics such as ancient books and paintings, their restoration is especially important due to their unique nature and susceptibility to environmental damage. Among various restoration materials, calcium hydroxide (Ca(OH)2) has been widely studied and applied in the protection of paper-based cultural relics. However, commercial Ca(OH)2 materials have issues such as a large particle size and slow carbonation. In order to address these issues, this study employed carboxymethyl cellulose (CMC) as a support, on which nano-sized Ca(OH)2 crystals were grown in situ on its surface, followed by loading with TiO2 nanoparticles, successfully preparing a multifunctional paper-based cultural relic restoration material with reinforcement, deacidification, anti-aging, and antimicrobial properties. It is worth noting that by in situ growing Ca(OH)2 on the surface of CMC, particle size control, uniform dispersion, and the fixation of Ca(OH)2 can be achieved. CMC is used to enhance the mechanical strength of the paper, Ca(OH)2 is used for deacidification, and TiO2 is used for anti-aging and antimicrobial purposes. This study provides a new approach and method for the restoration of paper-based cultural relics, simplifying traditional multi-step processes and avoiding potential impacts on the cultural relics from multiple repairs. [ABSTRACT FROM AUTHOR]

Vibration sensors are widely used in many fields like industry, agriculture, military, medicine, environment, etc. However, due to the speedy upgrading, most sensors composed of rigid or even toxic materials cause pollution to the environment and give rise to an increased amount of electronic waste. To meet the requirement of green electronics, biodegradable materials are advocated to be used to develop vibration sensors. Herein, a vibration sensor is reported based on a strategy of pencil-drawing graphite on paper. Specifically, a repeated pencil-drawing process is carried out on paper with a zigzag-shaped framework and parallel microgrooves, to form a graphite coating, thus serving as a functional conductive layer for electromechanical signal conversion. To enhance the sensor's sensitivity to vibration, a mass is loaded in the center of the paper, so that higher oscillation amplitude could happen under vibrational excitation. In so doing, the paper-based sensor can respond to vibrations with a wide frequency range from 5 Hz to 1 kHz, and vibrations with a maximum acceleration of 10 g. The results demonstrate that the sensor can not only be utilized for monitoring vibrations generated by the knuckle-knocking of plastic plates or objects falling down but also can be used to detect vibration in areas such as the shield cut head to assess the working conditions of machinery. The paper-based MEMS vibration sensor exhibits merits like easy fabrication, low cost, and being environmentally friendly, which indicates its great application potential in vibration monitoring fields. [ABSTRACT FROM AUTHOR]