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The rapid economic growth and environmental concerns have led to high demands on paper and paper-based products in terms of variety, quantity, quality, and specialty. Enhancement and functionalization with additives are constantly required. Moving away from traditional petroleum-based additives, researchers have attempted to use “green” nanoadditives by introducing renewable environmentally friendly nanocellulose. This article studies the functions of nanocellulose as bio-additives (enhancer, retention and filtration reagent, and coating aid) in paper and paper products, and overviews the research development of nanocellulose-based additives and their applications in the paper industry for both efficient production and paper functionalization. The review shows that (1) a variety of nanocellulose-based bioadditives have been reported for various applications in paper and paper-based products, while commercially viable developments are to be advanced; (2) nanocellulose was mostly formulated with other polymer and particles as additives to achieve their synergistic effects; (3) major interests have concentrated on the nanocellulose in the specialty papers as representing more value added products and in the efficient utilization of recycled fibers, which remains most attractive and promising for future development. This report shall provide most useful database information for researchers and industries for paper recycling and enhancement, and paper-based products innovation and application.

The appearance and quick spread of the new severe acute respiratory syndrome coronavirus disease, COVID-19, brought major societal challenges. Importantly, suitable medical diagnosis procedures and smooth clinical management of the disease are an emergent need, which must be anchored on novel diagnostic methods and devices. Novel molecular diagnostic tools relying on nucleic acid amplification testing have emerged globally and are the current gold standard in COVID-19 diagnosis. However, the need for widespread testing methodologies for fast, effective testing in multiple epidemiological scenarios remains a crucial step in the fight against the COVID-19 pandemic. Biosensors have previously shown the potential for cost-effective and accessible diagnostics, finding applications in settings where conventional, laboratorial techniques may not be readily employed. Paper- and cellulose-based biosensors can be particularly relevant in pandemic times, for the renewability, possibility of mass production with sustainable methodologies, and safe environmental disposal. In this review, paper-based devices and platforms targeting SARS-CoV-2 are showcased and discussed, as a means to achieve quick and low-cost PoC diagnosis, including detection methodologies for viral genomic material, viral antigen detection, and serological antibody testing. Devices targeting inflammatory markers relevant for COVID-19 are also discussed, as fast, reliable bedside diagnostic tools for patient treatment and follow-up., The authors acknowledge funding through projects Eco2Covid (POCI-01-02B7-FEDER-068174) and TecniCov (POCI-01-02B7-FEDER-069745), co-funded by FEDER through COMPETE2020 and Lisboa2020. T.P., A.R.C. and A.C.M. acknowledge funding to National Foundation for Science and Technology, I.P., FCT, through their PhD grants, references DFA/BD/8606/2020, SFRH/BD/130107/2017 and SFRH/BD/115173/2016, respectively, info:eu-repo/semantics/publishedVersion

Hydrothermal liquefaction derived hydrochar produced from industrial paper sludge was used as an adsorbent to remove phenol derivatives from an industrial wastewater stream. Removal efficiency for phenol was determined using synthetic solutions (10–150 ppm) using batch adsorption experiments at a constant solution pH (8), temperature (25 ± 2 °C) and rotary speed (150 rpm). The adsorption of phenol onto hydrochar followed a Freundlich isotherm and could be described with pseudo-second-order kinetic models. Analysis of the adsorption mechanisms showed that particle film mass transport was the rate-determining step in the adsorption process. A COD removal efficiency of 31 ± 1% was achieved for the industrial wastewater stream. All phenol components in the wastewater stream could be removed, but not all organic acids and cyclic ketones. The performance of the paper sludge-based hydrochar compared well with that of activated carbon (44% COD removal). The final phenol concentration in the wastewater stream was below the acceptable phenol concentration for industrial effluents (1 mg/L). The results show that paper sludge can be converted to a valuable marketable commodity that could reduce waste management costs for a paper mill, while also reducing the cost of expensive adsorbents. Highlights Industrial paper sludge waste was successfully converted to effective bio-adsorbent.; HTL-based biochar was used as adsorbent without any pretreatment.; 77.83% COD removal from industrial wastewater could be obtained.; Final total phenol concentration was below 1 ppm.; Bulk fluid mass transfer was the rate determining step in the adsorption process.

Cellulose paper, a material that is naturally derived, low cost, lightweight, eco-friendly, and mechanically deformable, plays important roles in producing next-generation flexible electronics. Following the booms in the development of functional electronics, the soft actuators built from cellulose paper have attracted great attention. In this focused review, the milestones and recent achievements of cellulose paper-based actuators are summarized. Electro-, thermal, moisture and magnetic actuation mechanisms are utilized to acquire energy from external stimuli. Corresponding functional materials and available fabrication techniques like film assembly and layer deposition are described. Programmable actions for the emerging applications in bionics, paper grippers and robots are realized by pursuing different strategies to control the responding deformation. Along with a conclusion, the existing challenges and possible solutions in evaluating and improving the performance of cellulose paper are summarized in the final section.

Natural yellow plant dyes and traditional medicines were used widely on historical papers in ancient China for religious reasons and conservation considerations. This study aims to evaluate some traditional yellow botanical sources of dyes that contain different chemical colorant compositions in order to understand their effects on the properties of traditional handmade paper. The physical and chemical changes in paper specimens treated with plant dyes were studied by examining properties such as the color, pH, thermogravimetric (TG) characteristics, tensile strength, folding endurance and microstructure by scanning electron microscopy (SEM). The results indicated that different colorants had different toning effects and that the main components, including carboxyl and ketone groups, could affect the paper stability at high temperatures. The results also revealed that the mechanical properties of paper specimens were improved after treatment with plant dyes. The significant improvements in the tensile strength and folding endurance and the slightly higher decomposition temperature of Amur cork tree-dyed paper could be ascribed to the strong interaction between the colorants’ main components and the fibers. The scientific evaluation of the property changes is therefore valuable information for weighing the advantages and disadvantages of the various yellow toning materials for paper conservation treatment.

A wide variety of biomass is available all around the world. Most of the biomass exists as a by-product from manufacturing industries. Pulp and paper mills contribute to a higher amount of these biomasses mostly discarded in the landfills creating an environmental burden. Biomasses from other sources have been used to produce different kinds and grades of biomaterials such as those used in industrial and medical applications. The present review aims to investigate the availability of biomass from pulp and paper mills and show sustainable routes for the production of high value-added biomaterials. The study reveals that using conventional and integrated biorefinery technology the ample variety and quantity of waste generated from pulp and paper mills can be converted into wealth. As per the findings of the current review, it is shown that high-performance carbon fiber and bioplastic can be manufactured from black liquor of pulping waste; the cellulosic waste from sawdust and sludge can be utilized for the synthesis of CNC and regenerated fibers such as viscose rayon and acetate; the mineral-based pulping wastes and fly ash can be used for manufacturing of different kinds of biocomposites. The different biomaterials obtained from the pulp and paper mill biomass can be used for versatile applications including conventional, high performance, and smart materials. Through customization and optimization of the conversion techniques and product manufacturing schemes, a variety of engineering materials can be obtained from pulp and paper mill wastes realizing the current global waste to wealth developmental approach.

In the present study, adsorption of colour and other pollutants from agro-based paper mill effluent onto fabricated coal fly ash nanoparticles (CFA-N) have been investigated. Response surface methodology was applied to evaluate the operational conditions for maximum ouster of colour from effluent by nano structured CFA-N. Maximum reduction in colour (92.45%) and other pollutants were obtained at optimum conditions: 60 min interaction time, 60 g/L adsorbent dosage and 80 rpm agitation rate. The regression coefficient values (adjusted R2 = 0.7169; predicted R2 = 0.7539) established harmony between predicted and the experimental data. The adsorption equilibrium results matched perfectly with both Langmuir and Freundlich isotherms with maximum adsorption capacity of 250 platinum–cobalt/g. Additionally, the efficacy of CFA-N was also assessed in a continuous column mode. Furthermore, the feasibility of treated effluent for irrigation purpose was checked by growing the plant Solanum lycopersicum. Overall, the findings demonstrated the outstanding role of inexpensive and abundantly available CFA-N in treatment of paper mill effluent to the required compliance levels. HIGHLIGHTS Nano fly ash was successfully utilized for removal of colour and other pollutants from agro-based paper mill effluent.; RSM using BBD was used to optimize the operational conditions.; Quadratic models have been established for the response variables.; Fixed-bed column adsorption studies illustrated the feasibility of nano fly ash for pilot-scale applications.; The reusability of treated effluent for irrigation was examined.

Graphical abstract During epidemics, such as the frequent and devastating Ebola virus outbreaks that have historically plagued regions of Africa, serological surveillance efforts are critical for viral containment and the development of effective antiviral therapeutics. Antibody serology can also be used retrospectively for population-level surveillance to provide a more complete estimate of total infections. Ebola surveillance efforts rely on enzyme-linked immunosorbent assays (ELISAs), which restrict testing to laboratories and are not adaptable for use in resource-limited settings. In this manuscript, we describe a paper-based immunoassay capable of detecting anti-Ebola IgG using Ebola virus envelope glycoprotein ectodomain (GP) as the affinity reagent. We evaluated seven monoclonal antibodies (mAbs) against GP—KZ52, 13C6, 4G7, 2G4, c6D8, 13F6, and 4F3—to elucidate the impact of binding affinity and binding epitope on assay performance and, ultimately, result interpretation. We used biolayer interferometry to characterize the binding of each antibody to GP before assessing their performance in our paper-based device. Binding affinity (KD) and on rate (kon) were major factors influencing the sensitivity of the paper-based immunoassay. mAbs with the best KD (3–25 nM) exhibited the lowest limits of detection (ca. μg mL−1), while mAbs with KD > 25 nM were undetectable in our device. Additionally, and most surprisingly, we determined that observed signals in paper devices were directly proportional to kon. These results highlight the importance of ensuring that the quality of recognition reagents is sufficient to support desired assay performance and suggest that the strength of an individual’s immune response can impact the interpretation of assay results. Supplementary Information The online version contains supplementary material available at 10.1007/s00216-021-03317-4.

Environmentally friendly and energy saving treatment of black liquor (BL), a massively produced waste in Kraft papermaking process, still remains a big challenge. Here, by adopting a Ni CaO Ca12Al14O33 bifunctional catalyst derived from hydrotalcite-like materials, we demonstrate the feasibility of producing high-purity H2 (∼96%) with 0.9 mol H2 mol−1 C yield via the sorption enhanced steam reforming (SESR) of BL. The SESRBL performance in terms of H2 production maintained stable for 5 cycles, but declined from the 6th cycle. XRD, Raman spectroscopy, elemental analysis and energy dispersive techniques were employed to rationalize the deactivation of the catalyst. It was revealed that gradual sintering and agglomeration of Ni and CaO and associated coking played important roles in catalyst deactivation and performance degradation of SESRBL, while deposition of Na and K from the BL might also be responsible for the declined performance. On the other hand, it was demonstrated that the SESRBL process could effectively reduce the emission of sulfur species by storing it as CaSO3. Our results highlight a promising alternative for BL treatment and H2 production, thereby being beneficial for pollution control and environment governance in the context of mitigation of climate change.

Background Lysine succinylation is a naturally occurring post-translational modification (PTM) that is ubiquitous in organisms. Lysine succinylation plays important roles in regulating protein structure and function as well as cellular metabolism. Global lysine succinylation at the proteomic level has been identified in a variety of species; however, limited information on lysine succinylation in plant species, especially paper mulberry, is available. Paper mulberry is not only an important plant in traditional Chinese medicine, but it is also a tree species with significant economic value. Paper mulberry is found in the temperate and tropical zones of China. The present study analyzed the effects of lysine succinylation on the growth, development, and physiology of paper mulberry. Results A total of 2097 lysine succinylation sites were identified in 935 proteins associated with the citric acid cycle (TCA cycle), glyoxylic acid and dicarboxylic acid metabolism, ribosomes and oxidative phosphorylation; these pathways play a role in carbon fixation in photosynthetic organisms and may be regulated by lysine succinylation. The modified proteins were distributed in multiple subcellular compartments and were involved in a wide variety of biological processes, such as photosynthesis and the Calvin-Benson cycle. Conclusion Lysine-succinylated proteins may play key regulatory roles in metabolism, primarily in photosynthesis and oxidative phosphorylation, as well as in many other cellular processes. In addition to the large number of succinylated proteins associated with photosynthesis and oxidative phosphorylation, some proteins associated with the TCA cycle are succinylated. Our study can serve as a reference for further proteomics studies of the downstream effects of succinylation on the physiology and biochemistry of paper mulberry.

Continuous manufacturing is an indicator of a maturing industry, as can be seen by the example of the petrochemical industry. Patent expiry promotes a price competition between manufacturing companies, and more efficient and cheaper processes are needed to achieve lower production costs. Over the last decade, continuous biomanufacturing has had significant breakthroughs, with regulatory agencies encouraging the industry to implement this processing mode. Process development is resource and time consuming and, although it is increasingly becoming less expensive and faster through high‐throughput process development (HTPD) implementation, reliable HTPD technology for integrated and continuous biomanufacturing is still lacking and is considered to be an emerging field. Therefore, this paper aims to illustrate the major gaps in HTPD and to discuss the major needs and possible solutions to achieve an end‐to‐end Integrated Continuous Biomanufacturing, as discussed in the context of the 2019 Integrated Continuous Biomanufacturing conference. The current HTPD state‐of‐the‐art for several unit operations is discussed, as well as the emerging technologies which will expedite a shift to continuous biomanufacturing., With an ever‐growing interest in shifting to integrated continuous biomanufacturing (ICB), the major gaps and state‐of‐the‐art perceived by academia and industry members in high‐throughput process development (HTPD) technologies for the development and implementation of this type of operation (ICB) are debated in this paper, with a special focus on the HT tools for the different unit operations in a typical biopharmaceutical process. The current needs in ICB and possible solutions to fulfill these needs are also highlighted

Achieving an efficient catalyst in the ATRP system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue. To attain the goal, herein, we used chitosan (CS)-modified cellulose filter paper (FP) as a green support for the synthesis of dip catalyst. The preparation of this catalyst involved surface treatment of the FP strips by CS coating through a dipping method, which increased the affinity of the substrate for adsorbing copper ions in the next step. The Cu@CS-FP catalyst was prepared without the requirement of any ligands. The synthesized dip-catalyst, in the form of the strips, was employed for the first time in the ATRP reaction of methyl methacrylate to assay catalytic activity. Catalytic insertion/ removal (ON/OFF) experiments were carried out during the polymerization. A reasonable control over the molecular weight with high conversion (68%) and polydispersity index of 1.32 under mild reaction conditions were obtained. Significantly, because of the facile separation of the catalyst, the amount of copper that remained in the polymer was very low (2.7 ppm). Also, the recyclability of the catalyst was investigated for five runs. The conversion in the final run was 64% without a loss of catalyst efficiency.

Detecting vascular endothelial growth factor C (VEGF-C), a kind of tumor biomarker, is of significant clinical importance in evaluating the prognosis of patients with cancer. However, laboratory analyses are usually not suitable for point-of-care testing because they are expensive and time consuming. In response to these challenges, we fabricated an origami paper-based microfluidic electrochemical device. To improve the specificity of VEGF-C detection, nanocomposites, synthesized by new methylene blue (NMB), amino-functional single-walled carbon nanotubes (NH2-SWCNTs), and gold nanoparticles (AuNPs), were used to modify the surface of working electrodes. Results of electrochemical detection showed that the immunosensor had excellent linearity, ranging from 0.01 to 100 ng mL−1 (R2 = 0.988), and the limit of detection was 10 pg mL−1. To confirm the high specificity of the device under real-world conditions, we evaluated the device using clinical serum samples from our hospital. The results demonstrated that the device had an excellent performance and could provide a platform for real-time detection of cancers., Sun, Wang et al. report an origami paper-based immunosensor for the electrochemical detection of the VEGF-C biomarker in blood serum. The immunosensor is made by modifying the surface of working electrodes with new methylene blue, amino-functional single-walled carbon nanotubes, and gold nanoparticles and demonstrates excellent performance with a limit of detection in the range of picograms per milliliter.

[EN] Recent trends in waste management have initiated interest in recycled materials for sound absorption applications. The present paper studies the possibility of paper sludge to be recycled as material for sound absorption applications. Paper sludge (PS) is the water treatment waste, produced during paper production. Two different methods were studied to produce paper sludge and slaked lime composite acoustic panels for sound absorption applications at low and mid-frequencies. The sound absorption coefficient of paper sludge composite panels is measured in an impedance tube using the two-microphone method. The samples produced with different methods showed different behaviours of sound absorption. The primary method to produce showed acoustic asymmetry in the vertical direction of the samples, and it was considerably fragile as well. An improved method to produce PS composite panels was proposed in this paper. Using this method, homogenous and robust acoustic panels were obtained., The authors would like to kindly thank the technician Javier Zaragoza Dolz and Dr. Olga Kizinievi for their fruitful suggestions on this study. This research was financially supported by the Ministry of Science and Innovation and the European Union FEDER through Project PID2019-109175GB-C22

Refereed/Peer-reviewed At a paper manufacturing mill (PML) that had been previously part of an integrated pulp (bisulphite) and paper mills industry, cyanobacterial blooms were observed in the mill’s aerated stabilization basin (ASB) ponds at about 3 years after pulping had been discontinued. This study aimed to determine the factors that led to bloom occurrences and potential control strategies applicable to the paper manufacturing mill’s, aerated stabilization basin system that discharges wastewaters into a coastal lake. Following discontinuation of pulping, the colour of the wastewaters reduced to low levels (~ 10 Hazen units or less), while the levels of nutrient remained potentially supportive of cyanobacteria growth with total phosphorus at ~ 0.1 mg/L and total nitrogen at > 2.5 mg/L. Incidences of blooms in the ABS were associated with preceding average monthly rainfalls and wind speeds being less (~ 44% and ~ 7%, respectively) and average direct sunlight hours being greater (~ 9%) than the long-term average values. Zinc was investigated for control of cyanobacteria as this metal is less toxic to aquatic organisms and microflora than copper algaecides. In laboratory culture trials, zinc was found to inhibit growth of M. aeruginosa (strain MIC338) and Pseudanabaena sp. when dosed at ~ 2.5 mg/L. The inhibition of cyanobacteria by zinc was found to vary between ASB pond samples which had different in situ chlorophyll a levels. This study found that the PML wastewaters investigated can be supportive of cyanobacterial growth to bloom levels after discontinuation of pulping processes and that zinc has potential as a cyanobacteria control agent.

Cellulose paper has strong potential as an analytical platform owing to its unique characteristics. In the present study, we investigated a procedure for functionalizing the surface of cellulose paper by dip-coating a mixture of a functional polymer and a perfluoroalkylated surfactant (surfactant 1). The functional polymer comprised a mixture of methyl methacrylate and poly(ethylene glycol) methacrylate monomers. The monomer ratio in the functional polymer affected the hydrophilicity and water absorbance of the cellulose paper after dip-coating. Furthermore, the presence of surfactant 1 during dip-coating promoted the surface segregation of poly(ethylene glycol) (PEG) moieties in the polymer, which enhanced the hydrophilicity, prevented nonspecific protein adsorption, and maintained the water absorbance of the dip-coated cellulose paper. Dip-coating with another functional polymer containing biotin groups produced a cellulose paper with a biotin-decorated surface in a one-step procedure. The displayed biotin groups immobilized avidin on the surface, and the PEG moieties in the polymer prevented nonspecific protein adsorption. We then immobilized a thrombin-binding DNA aptamer on the avidin-immobilized cellulose paper to prepare a paper-based analytical device. It is possible to visualize thrombin in model solutions and serum using the paper-based analytical device.

The recently adopted Ariel ESA mission will measure the atmospheric composition of a large number of exoplanets. This information will then be used to better constrain planetary bulk compositions. While the connection between the composition of a planetary atmosphere and the bulk interior is still being investigated, the combination of the atmospheric composition with the measured mass and radius of exoplanets will push the field of exoplanet characterisation to the next level, and provide new insights of the nature of planets in our galaxy. In this white paper, we outline the ongoing activities of the interior working group of the Ariel mission, and list the desirable theoretical developments as well as the challenges in linking planetary atmospheres, bulk composition and interior structure., Experimental Astronomy, 53, ISSN:0922-6435, ISSN:1572-9508

Phenotypic plasticity, the ability to produce multiple phenotypes from a single genotype, represents an excellent model with which to examine the relationship between gene expression and phenotypes. Analyses of the molecular foundations of phenotypic plasticity are challenging, however, especially in the case of complex social phenotypes. Here we apply a machine learning approach to tackle this challenge by analyzing individual-level gene expression profiles of Polistes dominula paper wasps following the loss of a queen. We find that caste-associated gene expression profiles respond strongly to queen loss, and that this change is partly explained by attributes such as age but occurs even in individuals that appear phenotypically unaffected. These results demonstrate that large changes in gene expression may occur in the absence of outwardly detectable phenotypic changes, resulting here in a socially mediated de-differentiation of individuals at the transcriptomic level but not at the levels of ovarian development or behavior., Connecting genotypes to complex social behaviour is challenging. Taylor et al. use machine learning to show a strong response of caste-associated gene expression to queen loss, wherein individual wasp’s expression profiles become intermediate between queen and worker states, even in the absence of behavioural changes.

An innovative survey was conducted of the collections of the historical Biblioteca Classense, located in the urban area of Ravenna (Northern Italy). The survey aimed to evaluate the current conservation state of the book collections, where 297 paper-based items, including incunabulae, manuscripts and books, dating from the 14th to the 20th century, were selected for analysis. This innovative survey was carried out non-destructively by assessing degradation visually and by measuring NIR spectral data followed by multivariate data analysis. Chemical and physical paper properties, important for paper characterisation and implementation of conservation strategies were determined, including paper type, pH, degree of polymerisation, tensile strength, lignin, protein, and rosin content. This survey provided a significant quantitative dataset for rag paper covering a 600-year period. The analysis of DP changes over time allowed the first experimental estimation of the rate constant for historical rag paper, i.e., (4.2 ± 0.6)·10−7 year−1, which was validated with predictions based on the Collections Demography dose response function for historic paper taking into account the past climate in Ravenna. Statistical methods were employed to describe the correlations between the measured variables and different features of the books, suggesting that the degree of polymerisation can be used as a general proxy for rag paper mechanical strength.

A paper-based electrode is a very attractive component for a disposable, nontoxic, and flexible biosensor. In particular, wearable biosensors, which have recently been attracting interest, not only require these characteristics of paper-based electrodes but must also be able to detect various ions and biomolecules in biological fluids. In this paper, we demonstrate the detection ability of paper-based metal electrodes for wearable biosensors as part of a wireless potentiometric measurement system, focusing on the detection of pH and sodium ions. The paper-based metal electrodes were obtained by simply coating a silicone-rubber-coated paper sheet with a Au (/Cr) thin film by sputtering then modifying it with different functional membranes such as an oxide membrane (Ta2O5) and a fluoropolysilicone (FPS)-based Na+-sensitive membrane, corresponding to the targeted ions. Satisfactory and stable detection sensitivities of the modified paper-based Au electrodes were obtained over several weeks even when they were bent to a radius of curvature in the range of 6.5 to 25 mm, assuming use in a flexible body patch biosensor. Moreover, the Na+ concentration in a sweat sample was evaluated using the paper-based Au electrode with the FPS-based Na+-sensitive membrane in a wireless and real-time manner while the electrode was bent. Thus, owing to their complex mesh structure, flexible paper sheets should be suitable for use as potentiometric electrodes for wearable wireless biosensors., Graphical abstarct

Paper waste is a raw material for a lot of products with different added value. The engineering, economic and environmental aspects of paper waste recycling are analysed for production of composite material, cellulose nanofibers and nanocrystals, bricks with paper components, porous carbon, film of biopolymer, enzymatic sugar and bioenergy: bioethanol, hydrogen and biofuel. Through multicriteria analysis, it was possible to determine the most feasible paper waste recycling product in case of four product groups: egg packaging boxes, cardboard, reused paper, cellulose nanomaterials (nanofibers and nanocrystals). The production of cellulose nanofibres and cellulose nanocrystals has an advantage over egg packaging and cardboard production as well as reusable paper.

In paper-based microfluidics, the simplest devices are colorimetric, giving qualitative results. However, getting quantitative data can be quite a bit more difficult. Distance-based devices provide a user-friendly means of obtaining quantitative data without the need for any additional equipment, simply by using an included ruler or calibrated markings. This article details the development of a quantitative DNA detection device that utilizes the aggregation of polystyrene microspheres to affect the distance that microspheres wick through filter paper. The microspheres are conjugated to single-stranded DNA (ssDNA) oligomers that are partially complementary to a target strand and, in the presence of the target strand, form a three-strand complex, resulting in the formation of aggregates. The higher the concentration of the target strand, the larger the aggregate, and the shorter the distance wicked by the microspheres. This behavior was investigated across a wide range of target concentrations and under different incubation times to understand aggregate formation. The device was then used to successfully detect a target strand spiked in extracted plant DNA.

Paper‐based microfluidics is characteristic of fluid transportation through spontaneous capillary action of paper and has exhibited great promise for a variety of applications especially for sensing. Furthermore, paper‐based microfluidics enables the design of miniaturized electrochemical devices to be applied in the energy sector, which is especially attractive for the rapid growing market of small size disposable electronics. This review gives a brief summary on the basics of paper chemistry and capillary‐driven microfluidic behavior, and highlights recent advances of paper‐based microfluidics in developing electrochemical sensing devices and miniaturized energy storage/conversion devices. Their structural features, working principles and exemplary applications are comprehensively elaborated and discussed. Additionally, this review also points out the existing challenges and future opportunities of paper‐based microfluidic electronics., Paper‐based microfluidics emerges as a powerful and versatile platform for constructing simple, inexpensive, environmentally‐friendly and high‐performing miniaturized electrochemical devices for various applications. This review summarizes the basics of paper‐based microfluidics and highlights some recent advances of paper‐based microfluidics in developing electrochemical sensing and energy storage/conversion devices. Their structural features, working principle and exemplary applications are comprehensively elaborated and discussed. This review also points out the existing challenges and future opportunities of paper‐based microfluidic electronics.

Flexible thin-film solar cells with high weight-specific power density are highly desired in the emerging portable/wearable electronic devices, solar-powered vehicles, etc. The conventional flexible metallic or plastic substrates are encountered either overweight or thermal and mechanical mismatch with deposited films. In this work, we proposed a novel substrate for flexible solar cells based on graphene paper, which possesses the advantages of being lightweight and having a high-temperature tolerance and high mechanical flexibility. Thin-film amorphous silicon (a-Si:H) solar cells were constructed on such graphene paper, whose power density is 4.5 times higher than that on plastic polyimide substrates. In addition, the a-Si:H solar cells present notable flexibility whose power conversion efficiencies show little degradation when the solar cells are bent to a radius as small as 14 mm for more than 100 times. The application of this unique flexible substrate can be extended to CuInGaSe and CdTe solar cells and other thin-film devices requiring high-temperature processing.

Paper spray ionization (PSI) is an extractive ambient ionization technique for mass spectrometry (MS), whereby a triangular paper tip serves as the sampling base and the electrospray tip. During PSI, analytes are extracted and transported to the edge of the paper tip by the applied spraying solvent. Analytes can be purified from a sample matrix and separated from each other by this transportation process. In this study, we investigated and utilized the analyte transportation process of PSI for the in situ separation and analysis of lipid mixtures. We found that differential transport of phosphatidylcholine (PC) and triacylglycerol (TAG), the two most abundant lipid classes in animals, occurred during PSI. We also found that the order in which these lipids moved strongly depended on how the spraying solvent was applied to the paper base. The more polar PC moved faster than the less polar TAG during PSI, when a polar solvent was slowly fed into a paper tip, whereas TAG was transported faster than PC when excess solvent was applied to the tip at once. In addition, we achieved a complete separation and detection of PC and TAG by slowly supplying a nonpolar solvent to a PSI tip.

This study introduces a novel geotechnical composite material comprising two types of fill material sourced from the paper industry-deinking paper sludge ash (DPSA) and deinking paper sludge (DPS). Five composites with different DPSA and DPS contents were investigated. Two composites were selected for further analyses. The technology and procedure for composite installation were implemented in field tests. The composites with 80% and 70% DPSA exhibited the elasticity required to withstand minor landslide slip deformations, in addition to achieving sufficiently high values of uniaxial compressive strength. The composites had a low maximum dry density value, which led to fewer settlements in the entire support structure. The enhanced shear characteristics can enable the construction of a thinner retaining wall. The delay between preparation and installation of the composites was further investigated. The field tests confirmed that the composites with 80% and 70% DPSA can be installed on the construction site 4 h and even 24 h after mixing. In 2018, a retaining wall structure with 70% DPSA and 30% DPS was successfully implemented near a railway line using conventional technology as followed-up research to the herein presented study. Results have been derived from work performed in the scope of the H2020 Paperchain project in which novel circular economy models centered on the valorization of the waste streams generated by the pulp and paper industry as secondary raw material for several resource-intensive sectors, including the construction sector, have been developed. Environmental benefits are savings in natural raw materials, reduction of landfill disposal as well as CO2 emission reduction. Nasl. z nasl. zaslona. Opis vira z dne 16. 11. 2021. Št. članka 22363. Bibliografija: str. 12-13. Abstract.

Over the past decades, paper-based lateral flow immunoassays (LFIAs) have been extensively developed for rapid, facile, and low-cost detection of a wide array of target analytes in a point-of-care manner. Conventional home pregnancy tests are the most significant example of LFAs, which detect elevated concentrations of human chorionic gonadotrophin (hCG) in body fluids to identify early pregnancy. In this work, we have upgraded these platforms to a higher version by developing a customized microfluidic paper-based analytical device (μPAD), as the new generation of paper-based point-of-care platforms, for colorimetric immunosensing. This will offer a cost-efficient and environmentally friendly alternative platform for paper-based immunosensing, eliminating the need for nitrocellulose (NC) membrane as the substrate material. The performance of the developed platform is demonstrated by detection of hCG (as a model case) in urine samples and subsequently indicating positive or negative pregnancy. A dual-functional silane-based composite was used to treat filter paper in order to enhance the colorimetric signal intensity in the detection zones of μPADs. In addition, microfluidic pathways were designed in a manner to provide the desired regulated fluid flow, generating sufficient incubation time (delays) at the designated detection zones, and consequently enhancing the obtained signal intensity. The presented approaches allow to overcome the existing limitations of μPADs in immunosensing and will broaden their applicability to a wider range of assays. Although, the application of the developed hCG μPAD assay is mainly in qualitative (i.e., positive or negative) detection of pregnancy, the semi-quantitative measurement of hCG was also investigated, indicating the viability of this assay for sensitive detection of the target hCG analyte within the related physiological range (i.e., 10–500 ng/mL) with a LOD value down to 10 ng/mL.

Nickel nanoparticles supported by commercial carbon paper (CP) are prepared by pulsed laser deposition with deposition time of 3, 6, and 12 min as a catalyst for urea electro-oxidation. The surface conditions and the morphologies of the prepared electrodes have been characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Urea electro-oxidation reaction in KOH solution on the Ni/CP electrodes is investigated by cyclic voltammetry and chronoamperometry. The results show that the electrode with less Ni nanoparticle agglomeration shows higher peak current density, which was achieved in the 3 min deposition samples when normalized by electroactive surface areas. However, the highest current normalized by the area of the carbon paper was achieved in the 6 min deposition sample due to the larger quantity of Ni nanoparticles. All the samples show good stability. Our results suggest that the low density, low cost, and environmental friendly CP can be used as support for Ni nanoparticle as a catalyst for urea electro-oxidation. It thus has great potential for many applications involving urea oxidation, such as wastewater treatments.

The Lewis-Clark Valley is a rural area that includes the cities of Lewiston, Idaho and Clarkston, Washington and the surrounding areas. The largest industry in the Lewis-Clark Valley is a pulp paper mill located in Lewiston which emits particulate matter and odorous sulfur air pollutants. This study analyzed the Lewis-Clark Valley air composition and seasonal, temporal and spatial variations of volatile organic compounds (VOCs) from 2017 to 2018 to determine potential health risks of the paper mill emissions to the surrounding community. Both active and passive air sampling via sorbent tubes were analyzed by thermal desorption - gas chromatography-mass spectrometry (TD-GC-MS). Fifty VOCs including benzene, toluene, chloroform, dimethyl sulfide and dimethyl disulfide were measured in the ambient air of the Lewis-Clark Valley at ten different sites, totaling over 800 samples. In addition, passive sorbent tubes were deployed in 2018 to obtain monthly averages in Lewis-Clark Valley and three urban locations in Idaho and Washington for comparison. United States Environmental Protection Agency (2001) methodology was used to assess cancer risks in the community based on the upper confidence levels of five carcinogens and nine air toxics. The Lewis-Clark Valley had similar levels of benzene to urban areas but had a strong signature of chloroform and sulfides from the paper mill. The cumulative cancer risk was 2 x 10-6 - 11 × 10-6 mainly due to the compounds chloroform, benzene and carbon tetrachloride. The hazard index of other air toxics was less than one. Overall, these air pollutants were considered low risk to the local population.

Development of paper-based microfluidic devices that perform colorimetric measurements requires quantitative image analysis. Because the design geometries of paper-based microfluidic devices are not standardized, conventional methods for performing batch measurements of regularly spaced areas of signal intensity, such as those for well plates, cannot be used to quantify signal from most of these devices. To streamline the device development process, we have developed an open-source program called ColorScan that can automatically recognize and measure signal-containing zones from images of devices, regardless of output zone geometry or spatial arrangement. This program, which measures color intensity with the same accuracy as standard manual approaches, can rapidly process scanned device images, simultaneously measure identified output zones, and effectively manage measurement results to eliminate requirements for time-consuming and user-dependent image processing procedures.

Invasive species can be particularly disruptive when they intersect with organisms of conservation concern. Stabilizing the declining eastern migratory population of monarch butterflies (Danaus plexippus) is projected to require extensive habitat restoration across multiple land use sectors including metropolitan areas. Numerous conservation programs encourage urban citizens to plant gardens with milkweeds, the obligate larval host plants of the monarch. Here, we show that predation by Polistes dominula, an invasive paper wasp that is particularly abundant in urban settings, can turn such sites into ecological traps for monarch larvae. Polistes dominula was the predominant paper wasp seen foraging in central Kentucky pollinator gardens. In 120 observed encounters with monarch larvae on milkweeds in gardens, most second to fourth instars were killed, whereas most fifth instars escaped by thrashing or dropping. The wasps bit and carried off second instars whole, whereas third and fourth instar kills were first gutted, then processed and carried away piecemeal. Predation on sentinel larvae was much higher in urban gardens than in rural settings. The wasps exploited ornamental butterfly “hibernation boxes” in pollinator gardens as nesting habitat. Polistes dominula is an under-recognized predator that may diminish the urban sector’s contributions to monarch habitat restoration.

Paper mulberry (Broussonetia papyrifera) is a tree species that has many economic, ecological, and social uses. This study developed an efficient protocol for regenerating shoots from leaf explants using Murashige and Skoog (MS) medium supplemented with different concentrations of plant growth regulators (PGRs), which play vital roles in shoot regeneration. The best result, 86.67% induction frequency and 4.35 shoots per explant, was obtained in the MS medium containing 2.0 mg/L N6-benzyladenine (BA) and 0.05 mg/L indole-3-butyric acid. The effects of explant age, orientation, and genotype were also investigated. Explants from young leaves had a greater regeneration frequency than those from old leaves, and the results were better when the distal end of the leaf explant contacted the medium versus the proximal end. Approximately 70.96% of the shoots rooted well in the MS medium containing 0.4 mg/L α-naphthalene acetic acid (NAA). Although some genotypes achieved poorer results, the regeneration protocol is still applicable for mass multiplication and genetic transformation.

Trap plays an important role in the charge transportation of three-layer oil-paper and the investigation of trap parameters at different degradation degree is of great significance for further research of the partial discharge (PD) mechanism. This article considers the turn-to-turn structure of on-board traction transformer. A defect model of three-layer oil-paper insulation was designed for PD test. The PD degradation samples are selected from the inception of PD to the breakdown of PD to study the characteristics of surface potential decay on degradation samples by using isothermal surface potential decay method. Given that, the trap distribution at different degradation stages was calculated and its influence on PD characteristics was investigated. The result shows that AC fluctuation voltages caused by inter-harmonic has a great influence on PD distribution, surface charge distribution and trap distribution. With the increase of degradation, the decay rate of surface potential increases and the decay rate of AC fluctuation voltages is larger than that pure AC. And also, the number of shallow trap with AC fluctuation voltages is larger than that with pure AC. The rate of free charge increases with the number of shallow trap increasing. More free electrons involves in the process of PD, accelerating the aging rate of three-layer oil paper samples. Therefore, it can be concluded that surface charge and trap distribution are helpful to clarify PD mechanism.

An electrical tree discharge model of multilayer insulation paper was prepared, and a voltage of 20 kV was used for electrical tree cultivation and initiation tests. Based on the microscopic image information and partial discharge (PD) information during the aging of the electrical tree, the development of electrical tree discharges between layers of paper comprising epoxy resin-impregnated paper insulation was studied. The results show that, by analysing PD information such as the discharge volume phase spectrum and the discharge repetition rate phase spectrum, the development of the electrical tree branch progresses in four stages: initial, growth, stagnation, and bursting. During the growth and stagnation stages, the main discharge paths of the electrical tree are mainly formed, and there are many filamentous fibres on the path edge. During the burst stage, more branches will be formed on the electrical tree, which will cause the greatest damage to the insulation. With the extension of the electrical tree path, the discharge magnitude and discharge times also increase. There are specific discharge patterns in different growth stages of the electrical tree, and the number of discharge events in each positive half-cycle is significantly greater than that in a negative half-cycle. Combining the microscopic image information and PD information during the aging of such an electrical tree, a theoretical basis for evaluating insulation state by PD monitoring is realised. The long-chain molecules of cellulose and epoxy resin break bonds and oxidise, which decompose into a large number of free radicals, monosaccharides, and other low-molecular-weight products.

The low frequency section of frequency domain spectroscopy (FDS) of oil-paper insu- lation system can effectively reflect the ageing state and moisture of the oil-immersed paper. Meanwhile, steady-state insulation resistance is the one of indexes for the condition of transformer. In actual measurement, these two both are time-consuming and poor accessibility, thereby restraining their field applications. Aim at this problem, this paper analyses the polarization process of the oil-paper insulation in transformer, and adopts a low frequency equivalent circuit model for the oil-paper insulation to characterize the polarization process at low frequency. The simulated annealing particle swarm optimization (SAPSO) algorithm is proposed to identify the parameters in equivalent circuit, which are affected by change of insulation state. Compared with the experimental results, the errors of the steady-state insulation resistance and the tan δ below 10-3 Hz, which are calculated by the identified parameters, are less than 2.5%. This method can avoid the influence from external environment and reduce the measurement time. The time and frequency domain parameters calculated can provide reference for the ageing assessment of oil-immersed paper.

Low consistency (LC) refining of (chemi-)thermomechanical pulp (TMP) provides an energy efficient alternative to high consistency refining for pulp property development. However, the benefit of LC refining is often limited by excessive fibre shortening, lower tear strength and a reduction of bulk caused by the refining process. In this study, microfibres produced by LC refining of TMP and kraft pulp fibres were investigated for their reinforcement potential in high freeness mechanical pulp. Primary pulp at 645 mL Canadian Standard Freeness was LC refined to different energy targets as a baseline for mechanical and optical property development. In contrast, the same primary pulp was reinforced with different microfibre types in ratios that yielded the same specific energies of the baseline LC refined pulp. The study revealed that at equivalent energies, the addition of TMP microfibres to the high freeness primary pulp displayed tensile development identical to the LC refined pulp, with significantly improved tear and bulk. The addition of kraft microfibre to primary pulp produced the highest tensile and tear strength but compromised light scattering. Additionally, all microfibre composites showed improved elongation, as opposed to no notable change in elongation with conventional LC refining. This investigation proposes an alternative, cost-effective approach for developing high bulk, high strength mechanical pulp by limiting the extent of second stage refining and using LC refined microfibres for pulp reinforcement. The high tear–high bulk open construction of the composite paper is likely to benefit boxboard and packaging applications.

Paper-based analytical devices have been substantially developed in recent decades. Many fabrication techniques for paper-based analytical devices have been demonstrated and reported. Herein, we report a relatively rapid, simple, and inexpensive method for fabricating paper-based analytical devices using parafilm hot pressing. We studied and optimized the effect of the key fabrication parameters, namely pressure, temperature, and pressing time. We discerned the optimal conditions, including a pressure of 3.8 MPa, temperature of 80 °C, and 3 min of pressing time, with the smallest hydrophobic barrier size (821 µm) being governed by laminate mask and parafilm dispersal from pressure and heat. Physical and biochemical properties were evaluated to substantiate the paper functionality for analytical devices. The wicking speed in the fabricated paper strips was slightly lower than that of non-processed paper, resulting from a reduced paper pore size after hot pressing. A colorimetric immunological assay was performed to demonstrate the protein binding capacity of the paper-based device after exposure to pressure and heat from the fabrication. Moreover, mixing in a two-dimensional paper-based device and flowing in a three-dimensional counterpart were thoroughly investigated, demonstrating that the paper devices from this fabrication process are potentially applicable as analytical devices for biomolecule detection. Fast, easy, and inexpensive parafilm hot press fabrication presents an opportunity for researchers to develop paper-based analytical devices in resource-limited environments.

info:eu-repo/grantAgreement/EC/H2020/787410/EU The work was also partially funded by the Nanomark collaborative project between INCM (Imprensa Nacional - Casa da Moeda). Publisher Copyright: © 2021 The Author(s). Published by IOP Publishing Ltd. Titanium dioxide nanoparticles and nanostructured thin films were simultaneously synthesized using a microwave-assisted hydrothermal method. The synthesis formed very fine particles, appearing as nanospheres in the 11 nm size range. As for the nanostructured films, they have displayed similar structural characteristics to the nanoparticles, with thickness of 130 nm. These films covered uniformly and homogenously the Whatman paper, while maintaining its flexibility. The materials processed had their photocatalytic activity assessed from rhodamine B degradation under solar radiation (91% degradation after 40 min for the powder material and 68% after 6 h for the nanostructured thin films). Reusability experiments were also carried out, revealing superior performance concerning the Degussa P25, the most common photocatalyst used. The results of the present work can be thought as an option for the existing photocatalysts activated under solar light, namely for water purification, as it simultaneously produces enhanced photocatalytic powders and photocatalytic papers fully disposable and that can be easily recycled. publishersversion published

The conservation of historic libraries can be referred towards both the ancient book collections and the buildings themselves. Heritage collections made of paper are threaten by climate-induced deterioration risks such as cellulose hydrolysis. Several studies have investigated the microclimate inside historic libraries but comparisons are difficult due to the lack of long-term microclimate observations and uniformity in the use of standards and risk assessment methods. For the first time, the long-term microclimate observations collected in three historic libraries in Italy were comparatively studied to outline differences and similarities of their microclimates in terms of paper preservation. A multidisciplinary approach was applied to assess the building performance (a) and the deterioration risks for the collections (b). As for a), a common feature of the libraries was the high thermal inertia and low indoor-outdoor air exchanges. As for b), the Time Weighted Expected Lifetime (TWEL) was defined to account for an average chemical risk on a seasonal and yearly basis. TWEL allowed to highlight the impact of the most adverse conditions on the overall chemical risk for acidic paper preservation (e.g., temperatures above 20 °C reached naturally in summer/artificially in winter). It resulted that the measured microclimate conditions in the libraries would lead to the loss of their acidic collections in less than 300 years. Demographic plots were finally used to inform about the risk resulting from the synergy between handling and microclimate as well as to explore the effectiveness of possible preservation measures such as the deacidification of 10% of the collections.

Bulk graphitic carbon materials with expanded interlayer spacing and abundant defects may serve as efficient anodes with high areal capacities for sodium-ion batteries (SIBs). However, obtaining long-range order in bulk graphitic carbon materials with expanded interlayer spacing is extremely difficult. Herein, an explosive decomposition method is demonstrated to realize thermally reduced graphene oxide (rGO) paper with tuned interlayer spacing. The in-situ temperature-dependent X-ray diffraction (td-XRD) was utilized to establish the correlation between heating rate and interlayer spacing. Based on td-XRD results, free-standing graphene paper (FSG) was synthesized at 450°C under a high heating rate of 70°C/min. The FSG exhibits a highly porous structure made of graphene flakes with abundant surface epoxy groups with an overall interlayer spacing of 0.38–0.39 nm. The rGO flakes in FSG are separated by large voids that provide fast mass transport pathways and allow expansion/contraction of crystallites upon reversible Na intercalation. The FSG was utilized directly as anodes without any binder and conductive agent and delivered an excellent reversible capacity of 290 mAh/g at a current density of 50 mA/g. Moreover, the FSG exhibited excellent foldability and rollability to create high areal density anodes, delivering an areal capacity of 0.62 mAh/cm2 at a current density of 100 μA/cm2. These results open the door to fabricate graphene material-based carbon anodes with tunable interlayer spacing for high-performance SIBs.

In recent years, microfluidic lab-on-paper devices have emerged as a rapid and low-cost alternative to traditional laboratory tests. Additionally, they were widely considered as a promising solution for point-of-care testing (POCT) at home or regions that lack medical infrastructure and resources. This review describes important advances in microfluidic lab-on-paper diagnostics for human health monitoring and disease diagnosis over the past five years. The review commenced by explaining the choice of paper, fabrication methods, and detection techniques to realize microfluidic lab-on-paper devices. Then, the sample pretreatment procedure used to improve the detection performance of lab-on-paper devices was introduced. Furthermore, an in-depth review of lab-on-paper devices for disease measurement based on an analysis of urine samples was presented. The review concludes with the potential challenges that the future development of commercial microfluidic lab-on-paper platforms for human disease detection would face.

The development of diagnostic tools for measuring a wide spectrum of target analytes, from biomarkers to other biochemical parameters in biological fluids, has experienced a significant growth in the last decades, with a good number of such tools entering the market. Recently, a clear focus has been put on miniaturized wearable devices, which offer powerful capabilities for real-time and continuous analysis of biofluids, mainly sweat, and can be used in athletics, consumer wellness, military, and healthcare applications. Sweat is an attractive biofluid in which different biomarkers could be noninvasively measured to provide rapid information about the physical state of an individual. Wearable devices reported so far often provide discrete (single) measurements of the target analytes, most of them in the form of a yes/no qualitative response. However, quantitative biomarker analysis over certain periods of time is highly demanded for many applications such as the practice of sports or the precise control of the patient status in hospital settings. For this, a feasible combination of fluidic elements and sensor architectures has been sought. In this regard, this paper shows a concise overview of analytical tools based on the use of capillary-driven fluidics taking place on paper or fabric devices integrated with solid-state sensors fabricated by thick film technologies. The main advantages and limitations of the current technologies are pointed out together with the progress towards the development of functional devices. Those approaches reported in the last decade are examined in detail.

This work reports the development and optimization of a rapid and low-cost pen-on-paper plotting approach for the fabrication of paper-based analytical devices (PADs) using commercial writing stationery. The desired fluidic patterns were drawn on the paper substrate with commercial marker pens using an inexpensive computer-controlled x–y plotter. For the fabrication of electrochemical PADs, electrodes were further deposited on the devices using a second x–y plotting step with commercial writing pencils. The effect of the fabrication parameters (type of paper, type of marker pen, type of pencil, plotting speed, number of passes, single- vs. double-sided plotting), the chemical resistance of the plotted devices to different solvents and the structural rigidity to multiple loading cycles were assessed. The analytical utility of these devices is demonstrated through application in optical sensing of total phenols using reflectance calorimetry and in electrochemical sensing of paracetamol and ascorbic acid. The proposed manufacturing approach is simple, low cost, flexible, rapid and fit-for-purpose and enables the fabrication of sub-“one-dollar” PADs with satisfactory mechanical and chemical resistance and good analytical performance.

The fabrication of low-cost, flexible, and recyclable electronic devices has been the focus of many research groups, particularly for integration in wearable technology and the Internet of Things (IoT). In this work, porous zinc oxide (ZnO) nanostructures are incorporated as a UV sensing material into the composition of a sustainable water-based screen-printable ink composed of car-boxymethyl cellulose (CMC). The formulated ink is used to fabricate flexible and foldable UV sensors on ubiquitous office paper. The screen-printed CMC/ZnO UV sensors operate under low voltage (≤2 V) and reveal a stable response over several on/off cycles of UV light exposure. The devices reach a response current of 1.34 ± 0.15 mA and a rise and fall time of 8.2 ± 1.0 and 22.0 ± 2.3 s, respectively. The responsivity of the sensor is 432 ± 48 mA W−1, which is the highest value reported in the literature for ZnO-based UV sensors on paper substrates. The UV-responsive devices display impressive mechanical endurance under folding, showing a decrease in responsivity of only 21% after being folded 1000 times. Their low-voltage operation and extreme folding stability indicate a bright future for low-cost and sustainable flexible electronics, showing potential for low-power wearable applications and smart packaging. publishersversion published

Currently, there is an increasing interest in the use of biopolymers in industrial applications to replace petroleum-based additives, since they are abundantly available, renewable and sustainable. Cottonseed protein is a biopolymer that, when used as a modifier, has shown improved performance for wood adhesives and paper products. Thus, it would be useful to explore the feasibility of using cellulose nanomaterials to further improve the performance of cottonseed protein as a paper strength agent. This research characterized the performance of cottonseed protein isolate with/without cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) to increase the dry strength of filter paper. An application of 10% protein solution with CNCs (10:1) or CNFs (50:1) improved the elongation at break, tensile strength and modulus of treated paper products compared to the improved performance of cottonseed protein alone. Further analysis using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that the cottonseed protein/nanocellulose composites interacted with the filter paper fibers, imparting an increased dry strength.

Point-of-care monitoring of hydrogen peroxide is important due to its wide usage in biomedicine, the household and industry. Herein, a paper sensor is developed for sensitive, visual and selective detection of H2O2 using a mesoporous metal oxide hollow sphere as a nanozyme. The mesoporous CuO hollow sphere is synthesized by direct decomposition of copper–polyphenol colloidal spheres. The obtained mesoporous CuO hollow sphere shows a large specific surface area (58.77 m2/g), pore volume (0.56 cm3/g), accessible mesopores (5.8 nm), a hollow structure and a uniform diameter (~100 nm). Furthermore, they are proven to show excellent peroxidase-like activities with Km and Vmax values of 120 mM and 1.396 × 10−5 M·s−1, respectively. Such mesoporous CuO hollow spheres are then loaded on the low-cost and disposable filter paper test strip. The obtained paper sensor can be effectively used for detection of H2O2 in the range of 2.4–150 μM. This work provides a new kind of paper sensor fabricated from a mesoporous metal oxide hollow sphere nanozyme. These sensors could be potentially used in bioanalysis, food security and environmental protection.

Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 °C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol−1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 °C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength.

The red imported fire ant (RIFA, Solenopsis invicta) is an exotic aggressive pest that is notorious for its ability to seriously harm humans and animals, cause economic loss to agriculture, and damage ecosystems. This is the first study to validate the capability of filter paper adsorption as a feasible odor bearer of RIFAs and evaluate its use in detection dog training. Two live RIFA-experienced detection dogs achieved a mean 92% positive indication rate (PIR) on RIFA-scented papers with a relatively low false response rate (0.8%). The similar accuracies in recognizing live RIFAs (96%) and scented papers (92%) suggest that a filter paper is an effective odor reservoir. After training with live RIFA and scented filter papers, both RIFA-experienced and inexperienced detection dogs successfully indicated filter papers that were scented with at least 10 RIFAs for 4 h with a high PIR (&gt, 93%) and low false response rate (2%). Detection dogs correctly recognized the filter papers scented by 10 RIFAs for 24 h with a 97.6% PIR. Even for scented samples stored at −20 °C and 4 °C for 13 weeks, the positive indication rates (PIRs) were as high as 90%. These results suggest that filter paper is an effective RIFA odor bearer, and the scent can be maintained at least 13 weeks for dog identification. After RIFA-scented paper training, detection dogs showed high (&gt, 95%) PIRs for both RIFA-scented paper and live RIFAs and also successfully performed field studies. Using filter paper as a RIFA odor bearer is an effective and economical method for detection dog training and RIFA identification.

Paper sludge is a solid waste by-product abundantly produced in the paper industry and contains fine minerals and lignocellulosic biomass. In this contribution, the ex-situ catalytic fast pyrolysis of paper sludge with a high mineral content of ca. 71 wt% is reported for the first time and demonstrated in a pilot-scale unit (feeding rate of 11.3 kg h−1) using a granular Na2CO3/γ-Al2O3 catalyst (loading of 650 g) to produce a high-grade bio-oil at a fast pyrolysis temperature of 475 ± 5 °C (pre-screened using a pyroprobe) and a catalytic upgrading temperature of 500 °C. Besides, > 99 wt% minerals in the paper sludge could be recovered, including paper fillers such as CaCO3 (major) and talc. The bio-oil obtained at a carbon yield of 21 C.% has a low oxygen content of 3.2 wt%, a low total acidity number of 5.2 mg KOH g−1, low H2O content of 0.7 wt%, and a high higher heating value of 40.9 MJ kg−1. It consists of value-added bio-based chemicals such as paraffins, olefins, and low molecular weight aromatics. The results demonstrate that the use of paper sludge to recover minerals and to obtain fuels and chemicals using ex-situ catalytic pyrolysis is technically feasible at a pilot plant scale, which will be of importance for the development of future bio-based economy.

To study the influence of different concentrations of zinc oxide (ZnO)/silicon dioxide (SiO2) composite coating on hydrophobic property and mechanical stability of paper mulch film, three kinds of ZnO/SiO2 composite coating paper mulch films (2%, 4%, 6%) with different coating substance contents were prepared by brush coating method. Through particle size analysis, contact angle, rolling angle and mechanical stability test, combined with scanning electron microscope, three-dimensional morphology and roughness measuring instrument, the optimal concentration of ZnO/SiO2 composite coated paper mulch film was screened out. Through acid-base salt corrosion test, silver mirror reaction and surface self-cleaning, the optimal concentration of composite coated paper mulch film was compared with the original paper mulch film to prove its excellent chemical stability and hydrophobicity. The results show that the paper mulch film with 4% coating material has excellent hydrophobicity and mechanical stability, can effectively reduce the surface roughness of paper mulch film, and has remarkable effects in resisting acid, alkali and salt and self-cleaning.