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Human papillomavirus (HPV) is one of the most common sexually transmitted infections which causes cervical cancer in women. In order to avoid the development of cancer and the onset of the disease, a reliable and on-site diagnosis for early screening of HPV is still required. To achieve this goal, a smartphone-assisted paper-based colorimetric assay using pyrrolidinyl peptide nucleic acid (acpcPNA) as a probe for the detection of HPV DNA was developed. Dextrin-stabilized gold nanoparticles (d-AuNPs) were used as the colorimetric reagent. The aggregation of the d-AuNPs can be induced by the outstanding properties of the positively charged acpcPNA, generating a distinctive color change. After the duplex formation between the acpcPNA probe and the HPV DNA target, the acpcPNA probe was depleted and the residual probe can cause different degrees of d-AuNPs aggregation, resulting in a detectable color change. The different color change before and after the introduction of the DNA target as a function of the DNA concentration was quantified by analyzing the color intensity through a smartphone application. Under the optimal conditions, the linearity in the range from 1 to 1000 nM with a correlation coefficient of 0.9996 and an experimental limit of detection of 1 nM was obtained. In addition, the acpcPNA probe exhibited high selectivity for the DNA target over single-base-mismatch, two-base-mismatch, and non-complementary DNA. Moreover, this DNA sensor was successfully applied for the detection of HPV DNA from cell line samples. The proposed smartphone-based colorimetric DNA sensor offers a simple, sensitive, and selective way of detecting HPV DNA. Therefore, this DNA sensing device can be utilized as an alternative tool for the point-of-care (POC) screening of HPV.

Woody and agricultural wastes are important fuels in many countries, and have the potential of being even more important in the future. The main problems of plant biomass combustion are low ash melting temperatures and increased emissions. The most widely used treatment to solve the problem of low ash melting point is blending a fuel with an additive. In this work, pellets were produced from wheat straw containing wood sawdust and paper sludge in the following proportions 40:40:20 and 45:45:10 (straw/sawdust/paper sludge). The purpose of this work was to study the influence of sludge and dendromass on the straw pellet parameters and combustion process. The highest calorific value of 15.71 MJ kg&minus, 1 was registered for a sample with a 10% paper sludge concentration. The effectiveness of paper sludge was proved, and the ash melting temperature was increased from 1025 to 1328 &deg, C for the same sample.

Coatings based on pigment and polymer binders are applied on paper surfaces to improve their surface, optical, and printing properties. Besides the coating composition, the structure and properties of the coated papers are influenced by the coating layer consolidation upon drying. In this study, the influence of drying conditions on the structure and properties of coating layers based on natural pigments (clay) and polymer binders (butadiene acrylonitrile latex) has been analyzed. Using a laboratory rod Mayer device, the coatings were applied as thin layer (about 15&ndash, 16 g/m2) on the paper surface and samples of coated paper were dried at 20 and 105 &deg, C temperatures. The optical, structural, and water absorption properties of the coating layer were evaluated by the measurement of gloss, opacity, void fraction, light scattering, and contact angle. The obtained results highlighted that both the drying temperature and latex content in the coating color have a synergic effect on the coated paper quality.

This study focuses on the mineral carbonation to capture CO2 using an alkaline industrial waste, the grits, formed during the kraft pulp production process. An indirect mineral carbonation route was adopted, composed by two steps: first the extraction of calcium from the grits and second the precipitation of calcium carbonate. Firstly, four solvents were analyzed (HNO3, CH3COOH, NaOH and NH4Cl). Only HNO3 and CH3COOH have shown significant extraction efficiencies of 79.4 and 73.2 %, respectively, after 2 h at 30 °C. Kinetic tests demonstrated that equilibrium conditions are reached after 60 min. Since the nitric acid is a corrosive acid and with high associated costs, the acetic acid was selected for the dissolution of grits and extraction of calcium. The optimal conditions determined were an acetic acid concentration of 2 M, solid/liquid ratio of 30 g/L and temperature of 45 °C with an efficiency approximately of 77 %. In the second step, carbonation experiments were performed contacting the Ca-rich liquor, obtained from the extraction step, with a flux of pure CO2 gaseous in a stainless inox reactor. The optimal conditions determined were 30 °C and 30 bar, reaching a carbonation efficiency of 74 %, corresponding a CO2 sequestration capacity of 460 kg CO2/ton of grits.

Sustainability demands circular and material solutions with an emphasis on using local resources. Using alternative fibers from invasive plants and agro-residue promotes local production in smaller...

Crease cracking of paperboard is important to control for the appearance and structural integrity of packages. Crease cracking is affected by creasing operation variables, as well as the physical properties of the paperboard. However, the effects of the physical properties are not clearly known. The objectives of this work were to identify the key material properties that affect crease cracking and to clarify the effects of fiber composition and starch. Laboratory sheets were produced from bleached and refined softwood and hardwood commercial pulp at grammage and thicknesses that match a typical paperboard. To mimic papermaking operations, surface starch was applied via a bench-top size press. The sheets were creased in the lab over a range of penetration depths, and reverse-side cracking was measured. The results showed that less reverse-side cracking was correlated with higher tensile post-peak energy, a lower bending stress, and a lower z-direction (ZD) stiffness. The tensile post-peak energy is a measure of the resistance to crack growth via fiber-bridging. The bending force and the ZD stiffness influence the forces that create cracks. It was observed that decreasing the ratio of hard-wood-to-softwood content and reducing the amount of starch would both decrease crease cracking.

The alarming global deforestation rate has great impacts on the output of the Pulp and paper Industry since wood is the principal papermaking fiber material. Although, generally, bamboo is an alter...

Carbon papers (CPs) are used as an electrode backing in PEMFC. It assists the diffusion of both the reactant gases and products toward and from the reaction site and aids the flow of electrons. CP ...

The aim of the study is to analyze the results of ecological monitoring of the aquatic biota of the river. Vychegda and their practical use on the example of water-intensive pulp and paper production. The availability of the results of our own studies of the actual values of the monthly biomasses of phytoplankton and zooplankton made it possible to assess the difference between the use of actual and literary data. According to actual data, the damage from the death of phytoplankton is 4.5 times lower, and of zooplankton – 97 times lower, compared with the results of calculations using literature data.

There is growing demand for simple to operate, sensitive, on-site quantitative assays to investigate concentrations of drug molecules in pharmaceutical preparations for quality assurance. Here, we report on the development of two colorimetric analysis methods for the study the antibiotic doxycycline hyclate (DOX) and the nasal decongestant oxymetazoline hydrochloride (OXY), in solution as well as in their respective formulations. We compare a UV/vis spectrophotometry method with a color change recorded on a microfluidic paper-based analytical device (μPAD). Detection is based on the pharmaceutical compounds coupling with diazotized 4-aminoacetophenone (DAAP) under alkaline conditions to produce colored azo-dye products. These azo-compounds were monitored by absorbance at 425 nm for DOX and 521 nm for OXY, with linear calibration graphs in the concentration range of 0.5–35 mg L−1 (DOX) and 1.0–40 mg L−1 (OXY) and limits of detection of 0.24 mg L−1 (DOX) and 0.32 mg L−1 (OXY). For the μPAD method, color intensity was measured from photographs and a linear increase was observed at concentrations from above approximately 15 mg L−1 for both compounds and up to 35 mg L−1 for DOX and 40 mg L−1 for OXY. The developed methods were also applied to the formulated pharmaceuticals and no interference was found from the excipient. Thus, the paper-based device provides an inexpensive, simple alternative approach for use outside centralized laboratories with semi-quantitative capability.

Paper-based colorimetric sensor array has attracted extensive attention due to its low-cost, easy-operation, powerful discrimination, good selectivity, rapid response and versatility. It combines the advantages of paper-based analytical devices and colorimetric sensor array, and extends its application fields in analytical chemistry. This review described the recent progress in paper-based colorimetric sensor array and summarized its applications in biomedicine, environmental and food safety. Moreover, the sensing materials, characteristics and performances of different paper-based colorimetric sensor arrays were investigated. The prospects of future research for the paper-based colorimetric sensor array were discussed.

In this work, we prepared novel cellulosic paper by incorporating tannin into the kraft pulp for potential application in active food packaging. The kraft pulp fibers were firstly periodate oxidized to obtain the dialdehyde cellulosic fibers, and then reacted with varied dosages of tannin to incorporate them into the fibers by covalent bondings between aldehyde groups on cellulose and active hydrogen on tannin. Handsheets were prepared using the tannin incorporated fibers through papermaking process and the properties were characterized. The percentage of tannin in the paper increased with the increase of the tannin dosage. FT-IR spectra confirmed the successful incorporation of tannin into the cellulosic fibers. It was found that paper after incorporation of tannin turned to be surface hydrophobic with contact angles higher than 90°, which may probably due to the covalent bonds between tannin and cellulose. The handsheets show high antioxidative and UV-shielding properties, which both increased with the increase of the tannin percentage in the paper. Water vapor transmission rate (WVTR) decreased after the incorporation of tannin, and this could facilitate its application in food packaging. The breaking length of tannin incorporated paper decreased insignificantly, less than 10% with the tannin percentage as high as 45%.

Paper sludge is the water treatment waste, which produced during paper production. Paper sludge (PS) waste utilization is the common problem in the EU and internationally. According to the waste management directive No. 2008/98/EC, paper sludge waste should not be utilized in landfills. In the European Union, alone 93 million tons of PS generated yearly. Nowadays most of the paper sludge waste used as fuel for incineration power plants (up to 55 %). According to waste management legislation such waste management should be avoided as well. Very small portion (10 %) of PS is used in construction sector. In construction, paper sludge used as additive in concrete composite materials. Such legislation of waste management generates the motivation of this study. In this study authors propose to produce composite panels in which PS is the main material of composite. As the binding material, clay proposed due to its good binding properties and therefore its natural material. Such produced panels proposed to use it for sound absorption applications. To determine composites sound absorption coefficient standard ISO 10534-2 method was used. The sound absorption coefficient in different octave bands reached up to 0.59.

As a new type of energy harvesting device, the triboelectric nanogenerator (TENG) can convert mechanical energy into electrical energy effectively. Paper-based materials have gained considerable attention for use in flexible energy harvesting device applications because of their flexibility, environmental friendliness (i.e., they are biodegradable and renewable), and foldability. This work proposes a strategy to use cellulose fibers layer as a spacer of paper-based triboelectric nanogenerator (P-TENG). The P-TENG consists of a three-layer fiber material and a copper electrode. The three-layer fiber material comprises nylon, cellulose, and polypropylene, where the cellulose fiber layer contains millimeter-sized holes and is used as a spacer. Because of its attractive cuttability and flexibility properties, the P-TENG can be applied on a large scale in complex environments (e.g., sports fields, driving training fields) to detect signal changes caused by external pressure This type of device has great potential for application to the large-scale TENG field and may provide a new solution for TENG industrialization.

Paper folding-and-punching tests are used to measure spatial abilities in humans. This paper presents a qualitative model for paper folding (QPF) and a computer game (Paper Folding Game) developed to apply and show the reasoning capabilities of the QPF model. This interactive game presents paper-folding activities intended to help users train and understand how to fold a paper to get a specific shape. Then, it presents paper-folding-and-punching tests to the players. The Paper Folding Game can automatically generate paper-folding-and-punching questions with varying degrees of difficulty depending on the number of folds and holes made, thus producing additional levels for training. The reasoning mechanisms in the QPF model are used by the Paper Folding Game to infer the right answer to each paper-folding-and-punching question. This reasoning capability allows the game to provide feedback to the players when they are wrong and also to create other plausible answers automatically, so that random question-answers are shown to the players in the master-mode. The Paper Folding Game has been implemented using Unity engine and it is available to download from GooglePlay and AppleStore for everyone to train their spatial reasoning skills.

A discussion is currently under way in the literature on the sustainable benefits of recycling material, particularly paper, which has high global consumption and polluting capacity. Optimized planning of waste paper recycling networks stimulates sustainable processing efficiency, motivating the investigation of quantitative methods to guide decision-making. The objective of this article is to review papers that present quantitative models for planning waste paper recycling networks considering optimization of the echelons of this process, to analyze the evolution of research, find research opportunities and contribute to future research. The article presents an analysis of five categories of the selected studies: I—evolution of publications; II—echelons considered in different waste paper recycling systems; III—the sustainability pillars considered in the objectives of the formulated model; IV—formulations and techniques used; and V—uncertainty analysis. The proposal for waste paper recycling networks involves summary of the echelons considered in selected articles, to help future analysis. Research suggestions involving sustainability objectives, especially considering social issues, using different solution techniques and considering uncertainty were identified. This study, by reviewing the articles and identifying possibilities for future research, contributes to the development of research using quantitative methods for the efficient management of waste paper recycling networks or similar arrangements.

We present a short review of several fundamental results, which have been obtained within frameworks of one trend of the wide spread of investigations, carried out during 1970 –2010s under the leadership of doctor of science, corresponding member of the National Academy of Sciences of Belarus P. D. Kukharchik, whose scientific interests were connected with the study of physical properties of heterogeneous dielectric and metal-containing industrial materials by the methods of holography, holographotomography, digital radiography, microwave and infrared introscopy. In this review, by the example of several base problems, we describe the semi-analytical methods of rigorous theoretical simulation of electromagnetic fields, arising under electromagnetic diffraction by slots in perfectly conducting screens of arbitrary thickness in absence and in the presence of plane dielectrics in the plane and cylindrical geometries of electromagnetic propagation. It demonstrates application of the these methods to simulation of processes of moisture measuring of paper sheet using microwave cavities with slots, which are employed on enterprises of pulp and paper industry.

Development of selective and sensitive methods for on-site assay of tetracycline (TC) is of great significance for public health and food safety. Herein, a valid ratiometric fluorescence strategy using g-C3N4 nanosheets coupled with Eu3+ is designed for the assay of TC. In this strategy, both Eu3+ and g-C3N4 nanosheets serve as the recognition units of TC. The blue fluorescence of g-C3N4 nanosheets can be quenched by TC via the inner filter effect (IFE); meanwhile, the red fluorescence of Eu3+ can be enhanced by TC through the antenna effect (AE). The synergistic effect of AE and IFE caused by TC makes the developed ratiometric fluorescent sensor display a wide linear range for TC from 0.25 to 80 μM with a detection limit of 6.5 nM and a significant fluorescence color evolution from blue to red. Given its simplicity, free-label, excellent selectivity, high sensitivity, and recognizable color change, point-of-care testing systems, including smartphones and test paper-based assays, are developed for the visual sensing of TC. The integration of smartphones and test paper on a ratiometric fluorescent sensor greatly reduces the detection cost and time, providing a promising method for the qualitative discernment and semi-quantitative assay of TC on-site. Moreover, the potential application of the approach is also verified by detecting TC in milk.

The growing need for reliable analytical tools to perform measurements at the point-of-need has prompted the development of novel sensors that are low cost, portable, sensitive, easy to use, and capable of multiplexed analysis. Miniaturization of the sensors into microfluidic platforms has become a promising approach to achieve these self-contained sensors. However, traditional microfluidics often require relatively expensive and complicated pumping mechanisms that increase the cost and limit the portability of the sensors. From a material perspective, paper is an attractive substrate for constructing point-of-need sensors because of its affordability, vast availability, and self-pumping ability, particularly when combined with electrochemical detection. In this mini-review, we discuss various strategies to achieve multiplexing or simultaneous detection of multiple analytes in electrochemical paper-based devices and provide a brief guide on selecting the detection strategy based on the electrochemical property of the analytes.

A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation.

The scope of the Nordtest method is to evaluate the moisture buffer value (MBV) of materials exposed to indoor air. The test is intended to simulate daily variations with relative humidity (RH) between 75 % during 8 hours and 33 % during 16 hours. The specimens follow a recipe that consists of waste paper, glue and water. Specimens made of paper plaster were covered with different colours. The results of the experiment showed that the type of paint used and the number of layers applied affected the MBV. Natural colours have a better moisture permeability than chemical paints, but the number of natural colour layers affects the MBV. The higher the number of layers, the lower the MBV.

This study demonstrates a method for patterning paper-based microfluidic devices. An octadecyltrichlorosilane (OTS) solution is used to coat a chromatography paper to make it hydrophobic. A low-temperature (~ 32.9 °C) atmospheric-pressure dielectric-barrier-discharge jet with a shadow mask is then used to pattern hydrophilic stripes on the OTS-coated hydrophobic paper. In this manner, 1-mm-wide hydrophilic stripes are patterned successfully. Liquids are demonstrated to be transported and mixed in the hydrophilic stripes. Water contact angle measurement, X-ray photoelectron spectroscopy, surface profiler, optical emission spectroscopy, and scanning electron microscopy are used to characterize effect of pattering.

Biodegradable coated paper materials represent one of the most promising alternatives to petroleum-based materials, including plastics and plastic-paper composite materials. Herein, fully biodegrad...

In this paper hemicellulose was separated by using 1-ethyl-3-methylimidazolium acetate (EmimAc, an ionic liquid) -water mixtures from a paper grade market bleached hardwood kraft pulp to produce dissolving pulp. Pure EmimAc dissolves pulp fibers completely in 30 min at ambient temperatures. By adding water (as an antisolvent to EmimAc system) the cellulose dissolution decreases and by optimizing the conditions, hemicellulose is largely removed while cellulose remains as the solid residue (dissolving pulp). At optimal conditions: molar ratio of water to EmimAc of 2, 60 °C, an alpha-cellulose content of 92.2%, with a high yield (78 wt%) was obtained. The viscosity of the solvent mixture decreases by increasing water to EmimAc molar ratio, which improves the mobility of ions, thus, facilitating their penetration into pores and lumens of the fibers during the dissolution process. Cellulose purity increases and purified cellulose yield decreases with the increases in temperature and water content (up to 2 wt%) in the mixture. This study implies that the optimal EmimAc/water mixture is an effective system to separate hemicellulose from hemicellulose/cellulose matrix.

The sensitive quantitative analysis of trace heavy metallic elements (Cd, Mn, Cr, and Cu) in aqueous solutions was achieved successfully through the combination of filter paper enrichment with laser-induced breakdown spectroscopy. Filter paper was enriched with 0.4 mL aqueous solutions to form a homogeneous sample layer on the surface of the metallic target. Considering the limits of detection, the values deduced with calibration curves already exhibited the high performance of the proposed method at several hundred or 10 μg/L (Cd 0.165, Mn 0.035, Cr 0.012, and Cu 0.078 mg/L), lower than or comparable to those using other similar methods. The LIBS results agreed reasonably well with those from ICP-MS for real samples. All results showed that our method was suitable and accurate for rapid on-site detection of trace metals in aqueous solutions. This indicates that filter paper enrichment combined with laser-induced breakdown spectroscopy is a feasible approach to wastewater quality monitoring.

Three copies of a book that had been optionally deacidified using two different procedures in 1967, and then subjected to accelerated aging, were tested again after 52 years of natural aging. Matched copies of the book Cooking the Greek Way, which had been printed in Czechoslovakia on acidic paper, were evaluated. Nonaqueous treatment of two of the copies with magnesium methoxide dissolved in chlorofluorocarbon solvent had been found in 1967 to have decreased the susceptibility to embrittlement, as evidenced by the results of the accelerated aging, followed by folding endurance tests. Retesting of the same books in 2019, after 52 years of room temperature storage, showed that the deacidification treatments had achieved the following benefits in comparison to the untreated book: (a) higher brightness; (b) higher folding endurance; (c) tensile breaking length higher in the cross-direction of the paper; (d) substantial alkaline reserve content, (e) an alkaline surface pH in the range 7.1–7.4, and (f) higher molecular mass of the cellulose. Remarkably, some of the folding endurance results matched those of unaged samples evaluated in 1967. Scanning electron micrographs showed no differences between the treated and untreated books.

In recent history, the Panama Papers have comprised one of the largest and most influential leaks detailing information on offshore entities, company officers and financial (and legal) intermediaries, and has led to a global exposé of corruption and tax evasion. A systematic analysis of this information can provide valuable insights into the structure and properties of these entities and the relations between them. Network science can be applied as a scientific framework for understanding the structure of such relational, heterogeneous datasets at scale. In this article, we use an existing, relational version of the Panama Papers to selectively construct various networks, and then study the properties of the underlying system using well-defined analytical methods from network science, including degree properties, country assortativity analyses, connectivity and single-point network metrics like transitivity and density. We also illustrate significant structural features in these networks by conducting a triad census and exploring the networks’ core-periphery structure. Together, these results are used to show that the Panama Papers constitute a distinct class of networks that differ significantly from ordinary social and information networks. We also propose, construct and analyze ‘higher-order’ networks from the raw data, such as a ‘social’ network of officers. We confirm that some of these higher-order networks also show significant non-random deviations from expected or typical behavior, including in their degree distributions.

Simultaneous enhancement in water flux and removal efficiency during the filtration process remains a big challenge for separation membranes. The porous structure of the filter paper can provide many channels for water transportation, but the separation performance is generally poor. The purpose of this study is to develop a new kind of filter paper consisting of ultralong hydroxyapatite (HAP) nanowires, cellulose fibers (CFs) and double metal oxide (LDO) nanosheets, and to achieve the simultaneous enhancement of both water flux and removal efficiency for high-performance dye separation. In this work, a novel kind of LDO/HAP/CF nanocomposite filter paper consisting of ultralong HAP nanowires and CFs and LDO nanosheets has been developed for rapid water filtration and highly efficient dye adsorption. Positively charged LDO nanosheets can adsorb on the surface of negatively charged ultralong HAP nanowires and embed in the porous networked structure of the LDO/HAP/CF nanocomposite filter paper, which can provide a porous structure for rapid water transportation and can adjust the pore size of the nanocomposite filter paper. As a result, the pure water flux of the LDO/HAP/CF nanocomposite filter paper can be adjusted. The optimized pure water flux of the LDO/HAP/CF nanocomposite filter paper can reach 783.6 L m-2 h-1 bar-1, which is 1.51 times that of the HAP/CF filter paper without LDO nanosheets (518.6 L m-2 h-1 bar-1). More importantly, the adsorption capacity of LDO nanosheets is high for dye molecules, the rejection percentage of Congo red (CR) by the as-prepared HAP/CF filter paper is only 59.8%, and its water flux is 534.7 L m-2 h-1 bar-1. The optimized rejection percentage and water flux of the LDO/HAP/CF nanocomposite filter paper for CR are significantly enhanced (98.3% and 736.8 L m-2 h-1 bar-1, respectively) compared to those of the HAP/CF filter paper. The size of LDO nanosheets has a significant effect on the water flux and dye rejection percentage of the LDO/HAP/CF nanocomposite filter paper. The as-prepared LDO/HAP/CF nanocomposite filter paper is promising for the applications in highly efficient purification of wastewater containing dye molecules.

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.

Abstract Tissue paper softness relies on two major factors, the bulk softness, which can be indicated by the elasticity of the sheet, and surface softness. Measurement of surface softness is complicated and often requires a multi-step process. A key parameter defining surface softness is the topography of the surface, particularly the crepe structure and its periodicity. Herein, we present a novel approach to measure and quantify the tissue paper surface crepe structure and periodicity based on the detection of waviness along the sample using laser scanning confocal microscopy (LSM) and X-ray tomography (XRT). In addition, field emission scanning electron microscope (FESEM) was used to characterize the tissue paper surface. We demonstrate that surface topography is directly correlated to the erosion of the doctor blade, which is used to remove the dry tissue paper from the Yankee cylinder. Because of its accuracy and simplicity, the laser confocal microscopy method has the potential to be used directly on the production line to monitor the production process of the tissue paper. XRT revealed more structural details of the tissue paper structure in 3D, and it allowed for the reconstruction of the surface and the internal structure of the tissue paper. Graphic abstract

In recent years, the need for portable, low-cost, and eco-friendly devices for testing and monitoring has arisen. Paper-based devices have emerged as a response to these needs due to the properties induced by capillarity, flexibility, disposability, and biodegradability. In this work, the authors explored the possibility of tuning the hygro-mechanical response of paper-based cantilever beams using glycerol. A lumped-parameter model with non-linear stiffness is used to describe the dynamic response of the beams using three parameters. An experimental method based on resonance frequency tests is used to study the influence of glycerol on the dynamic response of four different beam configurations. The obtained results demonstrate that the resonance frequency of paper-based mechanical systems can be easily tuned by the imbibition of a glycerol–water solution. This study could lead to the development of tunable paper-based mechanical systems for specific applications such as energy harvesters and hygro-mechanical-based sensors.

With the rapid emergence of wearable devices, flexible lithium-ion batteries (LIBs) are much more needed than ever. Free-standing graphene-based composite paper electrodes with various active materials have appealed wide applications in flexible LIBs. However, due to the prone-to-restacking feature of graphene layers, a long cycle life at high current densities is rather difficult to be achieved. Herein, a unique three-dimensional (3D) hierarchically porous NiO micro-flowers/graphene paper (fNiO/GP) electrode is successfully fabricated. The resulting fNiO/GP electrode shows superior long-term cycling stability at high rates (e.g., storage capacity of 359 mAh/g after 600 cycles at a high current density of 1 A/g). The facile 3D porous structure combines both the advantages of the graphene that is highly conductive and flexible to ensure rapid electrons/ions transfer and buffer the volume expansion of NiO during charge/discharge, and of the micro-sized NiO flowers that induces hierarchical between-layer pores ranging from nano-micro meters to promote the penetration of the electrolyte and prevent the re-stacking of graphene layers. Such structural design will inspire future manufacture of a wide range of active materials/graphene composite electrodes for high performance flexible LIBs.

A superhydrophobic paper with excellent robustness was fabricated by roll coating with modified nano-TiO2. First, nano-TiO2 particles were hydrophobically modified by γ-aminopropyltriethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS). Then the paper coating composed of modified nano-TiO2 particles as pigments and epoxy resin (EP) as adhesives was coated on a paper surface to create the desired surface morphology and surface energy. Compared with the uncoated filter paper, the prepared paper showed an improved rough surface morphology owing to the uniform layer of TiO2 microclusters deposited on the fiber network. The superhydrophobic paper exhibited water contact angles (WCA) about 153° ± 1.5°, and water sliding angles (WSA) about 3.5° ± 0.5°, low surface adhesion and excellent bounce ability. The superhydrophobic paper can withstand a variety of wear and tear, such as tape stripping and knife scraping. The as-prepared superhydrophobic paper showed mechanical durability even after 20 wear cycles with sandpaper,thus sustaining excellent superhydrophobicity on the filter paper surface. Moreover, it remains fully functional even in environments with high concentrations of acid and alkali for 96 h. The superhydrophobicity was not affected after storage for 6 months in a natural environment. It was confirmed that the superhydrophobic paper surface exhibited excellent chemical stability, long-term stability and self-cleaning properties. The entire production process was operated under normal environment, without complex equipment; and, as such, has the possibility for large-scale production and application in industry.

A method for treating cellulose paper using the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was developed. The treatment was intended to reform the paper structure. Filter paper was immersed in 20 g of molten [BMIM]Cl at 80 °C for 20–80 s and then washed with ethanol and distilled water. The treated paper was then immersed in tert-butyl alcohol before drying in a freeze dryer for 30 min. Next, polyethylene glycol (PG) and trichloromethylsilane were fixed to freeze-dried paper. The paper treated with [BMIM]Cl had a higher specific surface area than that not treated with [BMIM]Cl, and the specific surface area increased as the treatment time increased. The amount of PG fixed to the paper increased as the specific surface area of the paper increased, and PG improved moisture retention. The degree to which the moisture retention was improved was therefore related to the increase in the specific surface area caused by [BMIM]Cl treatment. Addition of trichloromethylsilane to the paper treated with [BMIM]Cl improved the hydrophobicity, and this was caused by the [BMIM]Cl treatment. Overall, [BMIM]Cl treatment was effective for reforming the paper structure and this improved the amount of functional material that could be fixed to the paper.

In the present analysis, a new experimental pilot plant system for exploring resin-impregnated paper (RIP) bushing technology was conducted. Experimental and numerical studies were carried out on the resin infusion and impregnation processes in the paper condenser core of a RIP bushing. An innovative approach for the molding process (named molding method B) of a commercial RIP bushing was implemented. For this method, the homogeneity of the paper winding process was controlled precisely. The filling process was conducted by gravity due to the difference of heights between two vacuumed chambers and from bottom to top in the mold. The flow front position and infusion time were measured experimentally and used to obtain the axial permeability of the paper condenser core analytically and numerically. The results indicate that the molding methods have a significant effect on the RIP bushing quality, homogeneous filling, and impregnating process time. Also, it was found that homogeneity of the paper winding process and, consequently, uniform axial velocity of resin flow in the radial direction is the most effective factor to eject the air. Finally, it was recognized that the determination of axial permeability in the case of transient flow is novel in comparison with conventional procedures such as Darcy relation of steady flows. By decreasing the paper thickness from 0.3 to 0.2 mm, the permeability decreased from 8.84 × 10−10 to 4.52 × 10−10 m2. The microstructure of the core illustrates that the axial permeability of the crepe paper condenser core is considerably affected by the variation of the paper thickness.

This study focuses on the production and characterization of biodegradable handmade paper from the Sida rhombifolia plant (SRP) cellulose. Sida rhombifolia plant is a seasonal plant that grows in the equatorial and tropical climates. The studies carried out on this SRP were aimed at investigating the methods required for the production of handmade paper from SRP plant and also at determining the tensile strength. Four specimens of SRP paper of different additive labels S0 (no additive), S1 (starch and KOH), S2 (starch), and S3 (Foska liquid glue) were produced using the Kraft method. Tensile properties (stress at break, elongation at break, and Young’s modulus), the rate of water absorption, and the rate of moisture absorption were carried out. Results showed that the addition of potassium hydroxide considerably reduces Young’s modulus of SRP handmade paper (S1) while the Foska liquid glue (S3) significantly improves it. In addition, the addition of potassium hydroxide and Foska liquid substantially improves the water absorption properties of the paper S2 and S3, respectively. The adhesive liquid creates more porosity and consequently increases the absorption of water. The addition of potassium hydroxide and Foska liquid significantly embedded the rate of moisture absorption. From the results obtained, it can be concluded that the paper S3 can be used as packaging paper since it has better mechanical properties and moisture absorption.

We present a high resolution, ultra-frugal printing of paper microfluidic devices using in-house paraffin formulation on a simple filter paper. The patterns printed using an office inkjet printer formed a selective hydrophobic barrier of 4 ± 1 µm thickness with a hydrophilic channel width of 275 µm. These printed patterns effectively confine common aqueous solutions and solvents, which was verified by solvent compatibility studies. SEM analysis reveals that the solvent confinement is due to pore blockage in the filter paper. The fabricated paper-based device was validated for qualitative assessment of Candida albicans (pathogenic fungi) by using a combination of L-proline β-naphthylamide as the substrate and cinnamaldehyde as an indicator. Our studies reveal that the pathogenic fungi can be detected within 10 min with the limit of detection (LOD) of 0.86 × 106 cfu/mL. Owing to its simplicity, this facile method shows high potential and can be scaled up for developing robust paper-based devices for biomarker detection in resource-limited settings. Graphic abstract

Serish (Eremurus) paste, made of Eremurus genus roots, is a strongly adherent substance which had traditionally been used for book binding and paper restoration in Iran for centuries. The proper pH of Serish and its quality of being reversible after long times has made it a good choice in restoring paper. However, it leaves yellow-brown stains on paper due to its own color, which had negatively affected conservator's desire to make use of this adhesive. Therefore the present study was intended to investigate the process of eliminating color from Serish, as a way of improving its quality for paper restoration. The study adopted solvent extraction method to eliminate color from Serish adherent polysaccharide. Extracted adhesives were coated on paper. Humid-thermal accelerated aging was carried out to investigate the effects of adhesives on pH, color change, tensile strength and cellulose structure of papers. It was found that stabilizing enzyme, using 70% boiling ethanol before extracting adhesive, is an effective method to inhibit enzyme operation and prevent creating new chromophores through enzymatic molecules degradation. This approach, on one hand, is useful in removing color and on the other hand proves effective in increasing pH of adhesives. Furthermore, it leads neither to paper acidification nor to damaging polymeric structure of paper after accelerated aging. The results confirmed that the adhesive extracted from the enzymatic stabilized roots by ethanol provides appropriate pH and color; it also improves the tensile strength of paper and yields more desirable results for conservation of paper-based documents, compared to the other examined samples.

Water is a prerequisite for the existence of life on earth. Rapid growth in the global population and industrialization have created a dearth of freshwater resources. Escalating water scarcity suggests that the use of passive solar stills is the most suitable and viable option in the arid and semi-arid areas around the world. In this study, the yield of wick type floating solar still is experimentally investigated for different wick materials. Capillary rise and absorbency of two different absorbers are considered as performance parameters for analysis of the research. Based on results, crepe paper with absorbency (1.8s) and capillary rise (112mm/h) proved a better absorber for higher productivity of the still. The efficiency of still with crepe paper was observed to be 16.68% higher than that of glass fiber sheet when applied in still during the investigation. The maximum internal temperature and the productivity of still were 9.1°C and 0.8 L/day respectively higher when crepe paper was used instead of a glass fiber sheet as a wicking material.

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.

Bladder cancer is the fourth most common cancer in men, and it is becoming a prevalent malignancy. Most of the regular clinical examinations are prompt evaluations with cystoscopy, renal function testing, which require high-precision instrument, well-trained operators, and high cost. In this study, a microfluidic paper-based analytical device (μPAD) was fabricated to detect nuclear matrix protein 22 (NMP22) and bladder cancer antigen (BTA) from the urine samples. Urine samples were collected from 11 bladder cancer patients and 10 well-beings as experiment and control groups, respectively, to verify the working efficiency of μPAD. A remarkable checkout efficiency of up to 90.91% was found from the results. Meanwhile, this method is feasible for home-based self-detection from urine samples within 10 min for the total process, which provides a new way for quick, economical, and convenient tumor diagnosis, prognosis evaluation, and drug response.

In this study, development of nanocoated paper and film to increase the shelf life of food has been demonstrated. Iron oxide (Fe2O3) nanoparticles were synthesized by neem leaves extract and characterized by UV-visible spectrophotometer, exhibited an absorption peak at 326 nm. Transmission electron microscope (TEM) showed the nanoparticles ranges between 5 nm to 50 nm and selected area electron diffraction (SAED) analysis revealed the amorphous in nature of nanoparticles. The biomolecules involved in the reduction of Fe2O3 nanoparticles were confirmed by Fourier transform infrared (FTIR) spectrum. The characterized nanoparticles were coated on cellulose paper, which was characterized by Scanning electron microscope (SEM). Coated paper was wrapped with fruit, and vegetables. Similarly, fruit and vegetables were also dipped in nanoparticle-incorporated sodium alginate solution. As a result, protein estimation and water loss were estimated on regular basis to determine the shelf-life of fruit and vegetables. The shelf-life of fruit and vegetables increases while evaluated with control and uncoated on weight loss and soluble protein content. Hence, the nanomaterial-coated paper and sodium alginate film prove its potential application as food packaging materials for longer shelf-life of food.

In this work, the feasibility of producing low-cost, recyclable and biodegradable binderless all-cellulose fibreboards was demonstrated through the successful manufacturing of self-binding composites based on recycled paper and kraft fibres. These all-cellulose composites were made by a simple and environmentally friendly solvent-free mechanical fibrillation method using water as a processing aid. Kraft fibres and recycled paper pulp were mixed in a 30/70 w/w ratio and refined simultaneously in a Valley beater for different periods of time. The mechanical properties of the composites, consisting of a ‘matrix’ of recycled paper reinforced with kraft fibres, were highly dependent on the level of fibrillation of the kraft fibres. Optimal levels of fibrillation resulted in a good balance of self-binding properties and reinforcing efficiency. The hot-pressed all-cellulose panels exhibited a flexural strength of 75 MPa and a modulus of 5·9 GPa, which are impressive values compared with those of conventional fibreboard materials. In addition, these panels showed better water resistance than some existing wood panel products. These binder-free all-cellulose composites have potential as cost-effective sustainable alternatives to existing panel board products, as they are entirely made from renewable and recycled materials, which at the end of life can potentially be recycled or composted, making them perfectly fit for a circular economy.

This work presents an unconventional use of capacitively coupled contactless conductivity detector (C4D) for detection of gas absorption by moist paper with potential application for chemical analysis. To be suitable for measuring conductivity of moist paper absorbent, the C4D sensor was therefore designed in planar configuration. A layer of dry filter paper, only 20 mm × 25 mm in size, was placed on the C4D sensor and the device installed inside a specifically designed vaporization chamber. A vial (16 mm i.d., 8 mm high) containing a 150-μL solution of sodium bicarbonate was placed alongside. The filter paper was loaded with 110 μL of deionized water through an injection hole in the cover lid. A 100-μL aliquot of 2 M hydrochloric acid solution was directly dispensed into the vial through a second hole in the lid to generate CO2 gas from the bicarbonate solution. It was observed that the C4D sensor gave real-time response that corresponded to the absorption of the gas and subsequent production of H+ and HCO3− in the moist paper. The monitored signal reached a constant value at 160 s after the addition of the acid. Chemistry of the absorption process and equivalent circuit for the C4D are proposed. Direct measurement of cement powder was chosen to demonstrate the potential use of this device for quantifying the CaCO3 content of the cement. The calibration curve for 0.5–3 mg CaCO3 was linear for signals recorded at 160 s: Vdc = (0.172 ± 0.005) · (mg CaCO3) + (0.016 ± 0.009), with coefficient of determination of 0.9965. Linear calibrations were also observed when the signals were monitored at various time less than 160 s. The limit of quantitation (3 SD of intercept/slope) was 0.17 mg CaCO3. The method provided acceptable precision with %RSD of 4.6 (2 mg CaCO3, n = 10).

Background Surface enhanced Raman scattering (SERS) based on highly sensitive, flexible, solid-state sensors can provide molecular vibrational fingerprints of targeted substances in point-of-care (POC) analysis. Cellulose paper offers many advantages for the build-up of silver and gold nanostructures on a three-dimensional scaffold. Such composites can be made to contain SERS hot spots required for sensitive SERS detection in an active solid-state sensor. Scope and approach In this review, we discuss the key technical issues involved in the fabrication of SERS sensors combining a metallic SERS substrate and a cellulose paper support. We then survey recent literature for methods designed to address these issues with applications to support food safety where POC analysis serves as a valuable tool. Key findings and conclusions Sensitivity of detection is a primal challenge in the development of a paper-based SERS substrate. The fibril structures of paper materials, a suitable modification for improved bonding at the paper-metal interface, and the surface conditions of metal nanostructures all contribute to sensitive SERS performance on paper. Continuing expansion of spectrum collection in a database format, diverse methods for the statistical analyses of Raman spectra, and advanced integration of portable Raman instruments with the mobile tele-networks are critical in the further development of flexible SERS sensor in POC testing of food-borne substances.

Several Indonesian paper mills utilize used paper as feedstock as the price is much cheaper and abundant availability, but the strength of the paper product tends to decrease. Xylan which is extracted from corncobs is a potential additive for upgrading the quality by modifying the fibre surface. This research studies the effect of sodium hydroxide concentration for extraction to produce an acceptable strength of paper product. The extraction process is at temperature of 90°C for 2 hours in a stirred tank reactor and the xylan product is deposited with 10 N acetic acid at pH of 4.5 - 5.0. Using 16% of NaOH concentration, the extraction produces 21.82% yield of xylan. With addition of this xylan product at mass ratio between xylan and corncobs of 5% increases 30.1% of the tensile strength and 31.83% of the tire strength. The optimum concentration of the use of NaOH in xylan extraction was at 16% NaOH with the largest xylan yield obtained at 21.82%.

Water–oil separation from their emulsions and mixtures has been a prominent topic in fundamental research and in industries. A superhydrophobic/oleophilic membrane (SHP) was obtained by dipping a cellulose filter paper in an acetonitrile solution of toluene diisocyanate (TDI) and in that of N-(2,4-diaminophenyl) maleimide, alternatively and repeatedly for three times, to make the paper coated by maleimide-containing polyurea (PU), which was then reacted with n-dodecanethiol (DAT) through Michael addition to obtain the superhydrophobic porous membrane (SHP). All the involved reactions were confirmed by different techniques. SHP membrane as prepared was demonstrated to be superhydrophobic and oleophilic and of high performance in separation of oil and water from their emulsions and mixtures. This study provides a new route to the fabrication of new materials of high superhydrophobicity and oleophilicity, featured by ease of fabrication, low-cost and versatile availability of the starting materials, both synthetic and natural.

Fluorine-free cellulosic paper was successfully obtained by coating the glassine base paper with eco-friendly cellulosic coating, which was made from dissolving cellulose in 8 wt% NaOH/12 wt% urea aqueous solution. Then the coated paper was severally immersed into CH3COOH, Na2SO4, and H2O solution to coagulate and regenerate. Benefiting from the compact matrix and fully covered surface, the resultant cellulosic paper exhibited favorable barrier properties and mechanical performance. Notably, the paper coagulated with CH3COOH displayed the reduction in water–vapor transmission rate, air permeability, and uptake of organic solvents due to its low porosity (26.8%) and narrow pore size distribution (0.1–0.36 µm). The tensile strength and elongation at break of papers treated by CH3COOH at coating weight of 5 g/m2 were increased by 72.1% and 34.0%, respectively. In summary, the fluorine-free cellulosic paper with high oil and grease resistance is attractive for the development of high-performance materials for food packing applications. Fluorine-free paper was obtained from the glassine base paper coated with eco-friendly, non-fluorinated, and degradable cellulosic coating, then coagulated with CH3COOH, Na2SO4, and H2O solution, respectively. The resultant functional papers displayed enhanced barrier properties (oil, organic solvent, vapor, and gas) and mechanical performance.

The aim of this work was the wettability improvement of clay-coated paper by ambient air plasma exposure. Industrial corona with a volume dielectric barrier discharge in cylindrical configuration was used as a plasma source; the exposure times varied from 0.25 up to 5 s. Water contact angle (WCA) measurement and surface free energy (SFE) evaluation were carried out for the estimation of wettability changes. Plasma treatment in the duration of 0.25 s was sufficient to decrease the WCA almost to the half of the original value, which was 76 degrees. SFE of paper has increased by 40%-50% after plasma treatment. Long-term ageing effect study of treated samples was carried out up to 3 months after the treatment. WCA did not reach the original value even after 3 months, and it was still 20%-30% lower. O/C ratio increased from 0.7 to 1.8 in case of 5-s plasma treatment, and the new chemical bonds (C=O, O-C=O) were created on the surface.

The use of nanocelluloses is being conducted for the most diverse applications. Their performance as coating agent has been mainly explored to improve barrier properties, as they emerge as perfect candidate for plastic substitution, but it is also important to explore their potential to improve printing quality. In the present work, the influence of different nanocelluloses, obtained through mechanical, enzymatic, TEMPO-mediated oxidation and carboxymethylation treatments, in the coating process and inkjet printability of office papers was assessed. The results revealed that the cellulose nanofibrils are better for printability than the microfibrils. But the size and charge of the former must be taken into account, since fibrils of very small size penetrate the paper structure, dragging the pigments from the surface, and very anionic nanofibrils can also have negative influence on the optical density. Besides, an interesting synergy between surface-sizing starch and the cellulose nanofibrils was found to occur as the latter closed the paper structure, which prevented starch from penetrating, while potentiating both of their positive effects on ink pigment entrapment. An additional study of characterization of inkjet pigments was also performed.