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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

This paper presents an application of a portable microfluidic platform based on a filter paper on which multi-walled carbon nanotubes were deposited to quickly determine the quality of olive oil by measuring electrical resistance. Three different types of filter paper with different pore sizes and different filtration rates were used in the middle of the microfluidic platform, as a material for soaking a blend of olive and high-oleic sunflower oil. The rapid prototyping xurographic technique was used to fabricate the complete microfluidic platform. For testing purposes, oil blends in various proportions were deposited through the inlet on the top of the platform. The variation in electrical resistance at room temperature was measured, using the Chemical Impedance Analyzer, successfully indicating oil proportions in measured blends. We obtained the change of resistance in the range from 0.26 MΩ to 2.79 MΩ per percentage of olive oil content, for corresponding linearity index from 0.71 to 0.99, for papers labelled with 44–45, respectively. Additionally, a prototype of electronic device was developed for acquisition and displaying measured data, based on the created microfluidic platform. • Rapid method for authentication of extra-virgin olive oil was established. • Microfluidic platform based on a filter paper with deposited MWCNTs was fabricated. • Electrical resistance was measured for blends of olive and high-oleic sunflower oil. • Proposed method effectively estimated portion of extra-virgin olive oil in blend. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reproducible sensors using biodegradable substrates and eco-friendly materials. • Use of cost-effective techniques for their fabrication. • Simplified layout for the joint measurement of RH and temperature on the same IDES. Given the increasing number of connected devices as a consequence of the Internet of Things (IoT) revolution, the issue of the removal and recycling of electronics is becoming more and more urgent. In this context, biodegradable electronics is expected to be one of the biggest technological revolutions to tackle this problem. Following this direction, in this work we present the fabrication and characterization of temperature and humidity sensors based on biodegradable materials with the goal of making their removal easier as well as reducing their environmental impact. In particular, these multi-sensing devices were fabricated following a screen-printing process using a carbon-based paste and a conjugated polymer, both on paper and on a water soluble substrate. The results are more than promising and show how with our biodegradable sensors it is possible to obtain a sensitivity of 1 dec/20%RH to moisture content and around 0.04%/°C sensitivity to temperature. It is demonstrated that the simplicity and flexibility of the fabrication approach followed in this work paves the way to a set of new "green" IoT nodes that could be extended to wide range of sensing applications. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) films were deposited on paper sheets using a low-frequency (60 Hz) DC-pulsed magnetron sputtering (LF-DPMS) with a modified sputtering gun. The deposited ITO films exhibited a cubic structure with a grain size of 20.5 nm. The work function of the films was 4.94 eV, and the surface was highly hydrophobic with a contact angle of 116°. The transmittance at a wavelength of 550 nm was 86.6% and the optical bandgap was 3.33 eV. The resistivity and the sheet resistance were 8.08 × 10−3 Ωcm and 40.4 Ω/□. By the end of the deposition process, the fabric structure of the paper sheet remained in good condition, and the as-deposited paper sheet did not bend due to the residual stress of ITO films. From these results, LF-DPMS is considered a damage-free deposition technique, and is rather effective for film depositions on weak substrates including papers, polymers, and fibers. • ITO films were deposited on paper substrate using a LF-DPMS. • ITO films had sheet resistance of 40.4 Ω/□, and highly hydrophobic surface state. • There was no observation of paper bending due to residual stress of ITO films. • The LF-DPMS was able to deposit films on weak substrates without substrate damage. [ABSTRACT FROM AUTHOR]

Recently, flexible intelligent wearable devices are in highly demand and it is urgent to increase the flexibility of traditional devices. Organometallic trihalide perovskite materials have become a hot spot in the photoelectric field due to its outstanding optoelectronic properties, which can be crystallized from solutions and vapors. Herein, we demonstrated a simple approach to flexible thin CH 3 NH 3 PbI 3 perovskite films on paper substrates using a dual-source physical vapor deposition method and a brush-coating method. The photodetector devices from the two methods have similar photodetecting and repeatable performances. They well maintained the optoelectronic functionality under bending conditions. Typically, up to 75% of its initial photocurrent was remained after 500 bending cycles, demonstrating good stability against bending deformation. Additionally, a 6 × 6 perovskite photodetector array based on stretchable origami-based techniques were fabricated. It has excellent all-optical acquisition capability and provides potential application in three-dimensional photo sensing. [Display omitted] • Thin perovskite films were deposited on paper substrates using both vapor and solution methods. • The paper-based photodetectors demonstrated good stability against bending deformation, even up to 500 bending cycles. • An origami-based perovskite photodetector array has excellent all-optical acquisition capability. [ABSTRACT FROM AUTHOR]

• Compared the performance of three algorithms in classifying the age of documents. • FTIR combine with chemometrics can classify the documents of different years. • CNN are proved to be an effective technique. A non-destructive method based on Fourier Transformed Infrared Spectroscopy (FT-IR) was proposed to estimate the date of paper from different years in this article. For the paper samples, dated from 1940 to 1980, naturally aged and conserved in library. Partial least squares-discriminate analysis (PLS-DA), Logistic regression and convolutional neural network (CNN), were employed to evaluate the date of paper, with the accuracy 60.74%, 95.31% and 98.77%, respectively. Based on the characteristics of CNN model and with the help of network localization, active variables could be recognized in the whole spectrum. Although the localization of active variables showed a discriminative pattern, the selected spectral regions were similar. Most important variables focused on the 1700–1400 cm−1, were corresponding to cellulose crystallinity, which was consisted with the ageing processing. The present work gave the potential of FT-IR combined with chemometric techniques could estimate the dating of unknown paper. Meanwhile, the analysis of active variables obtained further indicated the worthy of CNN model for document dating. [ABSTRACT FROM AUTHOR]

• Supercritical CO 2 displaces water from alum, wastewater, and paper sludge. • Multistage dewatering increases the degree of dewatering. • The expanding CO 2 blows out the water during decompression. Supercritical CO 2 (sCO 2) displaces water from wastewater, alum, and papermill sludge. The sCO 2 appears to enter the sludge matrix through viscous fingering through the entrained water. Because the water removed far exceeds the solubility of water in sCO 2 , it must be displaced by the sCO 2 rather than dissolved out. Adding a small amount of soap to the sludge converts some of the bound water into free water, which can then be displaced by sCO 2. Application of the sCO 2 in multiple stages greatly enhances dewatering as compared to a single stage process. Approximately 70, 70 and 85% of the initial water can be removed from alum, wastewater and paper sludges, respectively, through a five-stage process. Staged application of sCO 2 doubles the efficiency of water removal over a single-stage process of the same duration. It is proposed that when the sCO 2 entrained in the sludge is decompressed between stages some of the water is explosively displaced by the expanding CO 2. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Here, we prepared planar polypyrrole (PPy) coated paper-based supercapacitors by applying simple laser carving assisted method. The planar structure of the device showed a significant performance improvement (13.9 mF/cm2) compared to the sandwiched structure device (12.3 mF/cm2). In addition, by adjusting the polymerization time of pyrrole, the device capacity can be further increased to 87.4 mF/cm2. We firmly believed that the laser carving assisted method has a significant role in promoting the development of flexible planar electronic devices. • Planar PPy coated paper-based supercapacitors were obtained by laser carving. • The planar device showed a significant performance improvement. • The optimal device capacity can be further increased to 87.4 mF/cm2. Paper-based supercapacitors have attracted more and more attention for high electrochemical performance. However, most of them adopt sandwiched structure. Here, we prepared planar polypyrrole (PPy) coated paper-based supercapacitors by applying simple laser carving assisted method. The planar device showed a significant performance improvement (13.9 mF/cm2) compared to the sandwiched device (12.3 mF/cm2). In addition, by adjusting the polymerization time of pyrrole, the device capacity can be further increased to 87.4 mF/cm2. We firmly believed that the laser carving assisted method has a significant role in promoting the development of flexible planar electronic devices. [ABSTRACT FROM AUTHOR]

Cellulosic nanomaterials are in the focus of academia and industry to realize light-weight biobased materials with remarkable strength. While the effect is well known, the distribution of these nanomaterials are less explored, particularly for paper sheets. Here, we explore the 3D distribution of micro and nanosized cellulosic particles in paper sheets and correlate their extent of fibrillation to the distribution inside the sheets and subsequently to paper properties. To overcome challenges with contrast between the particles and the matrix, we attached probes on the cellulose nano/microparticles, either by covalent attachment of fluorescent dyes or by physical deposition of cobalt ferrite nanoparticles. The increased contrast enabled visualization of the micro and nanosized particles inside the paper matrix using multiphoton microscopy, X-ray microtomography and SEM-EDX. The results indicate that fibrillary fines enrich at pores and fiber-fiber junctions, thereby increasing the relative bonded area between fibers to enhance paper strength while CNF seems to additionally form an inner 3D network. [ABSTRACT FROM AUTHOR]

• Cellulose-based solutions can improve environmental performance of food packaging. • Food products require specific barrier functions from cellulose-based packaging. • Eco-design enables quantifying environmental performance and identifying trade-offs. • Fulfilling the barrier requirements for food product packaging is crucial. This short communication describes the climate change impacts of using cellulose, and more precisely cellulosic fiber-based materials, in food packaging, representing current and emerging industrial state of the art technology, without specific reference to current scientific advances. First, the different types of cellulosic fiber-based packaging materials, which can be used to replace fossil-based packaging materials, are presented for flexible and rigid applications. The focus is on technological solutions with packaging properties that enable the protection of commonly sold food products. The manufacturing processes associated with these cellulosic fiber-based materials is described and the environmental impact assessment of 4 selected case studies presented: stand-up pouches, flexible flow wraps, frozen or chilled food trays, and molded pulp lids. A simplified eco-design Life Cycle Assessment (LCA) was then performed to compare each solution with its fossil-based counterpart. Differences and similarities between the various cellulosic solutions have been identified. Furthermore, the assessment confirms that cellulosic fiber-based materials have reduced environmental impacts as compared to fossil-based counterparts, if a similar packaging weight is obtained. Indeed, all impacts of plastics are between 3 and 5 kg CO 2 eq/kg, while all impacts of cellulosic fiber-based materials are below 1.5 kg CO 2 eq/kg. [ABSTRACT FROM AUTHOR]

In 2020 the Cellulose and Renewable Materials Division (CELL) of the American Chemical (ACS) society celebrates its 100th anniversary. The following paper is based on a chapter from the book commissioned by the Division (Patterson, 2021). CELL is one of the most successful and dynamic Divisions in the ACS. It has evolved throughout its history to remain relevant and productive. One of its strengths is its diversity, while staying true to its founding vision. This perspective was present at its founding, and the following paper surveys the world of cellulose and renewable materials from the dawn of history to 1920. CELL has both industrial and scientific roots and has always welcomed the full range of participants from these communities. Rather than operating as separate tribes, the two groups have fostered innovations in each other. Many aspects of cellulose science and technology are discussed from antiquity to the early 20th century. [ABSTRACT FROM AUTHOR]

Solution-phase deposition of nanomaterials represents a highly promising technology with strong industrial application potential for the fabrication of superhydrophobic surfaces. An important barrier towards the adaptation of such materials and processes in a broad range of applications is the limited mechanical durability of the nanostructures. Herein, we present a universal solution to this challenge by benefiting from the unique micro-structure of paper. Our approach is based on transferring the structure of paper into a target material, to form a mechanical protection layer for nanomaterials that were deposited from solution-phase, i.e. spray-coating. We demonstrate this concept through the transfer of the structure of paper to a free-standing PDMS film using a simple molding process. Spraying a dispersion of alkyl-silane functionalized silica nanoparticles on the structured free-standing film results in a hierarchically structured superhydrophobic surface with a water contact angle of 175° ± 2° and a sliding angle <2° ± 1°. The fabricated superhydrophobic surface displays high levels of mechanical, chemical and thermal stability. The robust, inexpensive, scalable, flexible, and environmentally friendly nature of the presented approach may be a key enabler in superhydrophobic coating applications. Unlabelled Image • Transferring the structure of paper as a generalizable strategy for fabrication of robust superhydrophobic surfaces • All-solution processable, inexpensive, scalable, and environmentally friendly fabrication • Inherently flexible coatings adaptable to virtually all types of substrates [ABSTRACT FROM AUTHOR]

From the first investigations on peptide nucleic acids (PNA), peculiar features have been described as intrinsic of the singular chemical nature of these biomolecules. Relevant applications in the development of biosensors occurred in the last decades, exploiting them as bioreceptors. Their outstanding chemical and thermal stability as well as highly sensitive towards both complementary and non-complementary sequences, promoted them in the Olympus of biocomponents for applications in diagnostics. The intent of this review (85 ref) is to describe the last trends on the astonishing PNA technology in the biosensing field, in the view of the positive contamination with vanguard technologies including rational design and nanotechnology. In particular, electrochemical and optical biosensors exploiting PNA were reported from the literature, as well as nanostructured and paper-based biosensors for the design of microfluidics and lab-on-chip tools. • PNAs mimic DNA in binding oligonucleotide sequences through Hoogsteen base pairing in the major groove. • PNAs show outstanding stability and sensitivity towards both complementary and non-complementary sequences. • Vanguard technologies as rational design, nanotechnology, and microfluidics boost PNA use as smart bioreceptors for biosing. [ABSTRACT FROM AUTHOR]

Several tropical fever viruses transmitted by mosquitoes including zika, dengue, and chikungunya , are becoming a serious problem in global public health. Simple diagnostic tools in early stages are strongly required to monitor and prevent these diseases. Paper diagnostic platforms can provide a solution for these needs, with integration of fluidic control techniques and isothermal amplification methods. Here, we demonstrate a Lab-on-paper for all-in-one molecular diagnostics of zika, dengue, and chikungunya virus from human serum. The entire process of nucleic acid testing that involves sampling, extraction, amplification, and detection is simply operated on a single paper chip. Based on the engineered structure of paper materials and dried chemicals on the all-in-one chip, serum samples containing the target virus RNA were simply added by automatic flow from distilled water injection. Target RNA molecules were concentrated on the binding pad with chitosan and then transported to reaction pads following a pH increase for specific reverse transcription loop-mediated isothermal amplification with fluorescence signal generation. Three targets, zika virus, dengue virus, and chikungunya virus, in human serum were simultaneously detected on the all-in-one paper chip within 60 min at 65 °C. The all-in-one paper chip can be used as a real-time quantitative assay for 5–5000 copies of zika virus RNA. This all-in-one device was successfully used with 5 clinical specimens of zika and dengue virus from real patients. We believe that the proposed all-in-one paper chip can provide a portable, low-cost, user-friendly, sensitive, and specific NAT platform with great potential in point-of-care diagnostics. Image 1 • All-in-one nucleic acid testing paper chip from sample to result was demonstrated. • The entire nucleic acid testing process, sampling, extraction, amplification, and detection were conducted on single device by simple injection of sample. • Zika, dengue, and chikungunya spiked in serum samples were simultaneously detected and quantified within 60 min by RT-LAMP. • Small volumes, 5 clinical samples, and 5–5000 RNA copies were analyzed in real-time. • A fully-integrated, portable, low-cost, ready-to-use, easy-to-fabricate, sensitive, and specific paper-based nucleic acid testing system was developed. [ABSTRACT FROM AUTHOR]

• Fabrication of flexible paper temperature sensors with 658.5 Ω/°C. • Temperature sensitivity of 658.5 Ω/°C, which is 14 times higher than that of sensor with polymer substrate (46.0 Ω/°C), for the temperature range of 30–42 °C. • Reliable process against atmospheric humidity. • Implement a body-attachable temperature patch for wearable thermometer. A highly sensitive, flexible, and wearable paper-based temperature sensor is fabricated using printing paper and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) solution. It exhibits a negative temperature coefficient and is implemented in a new band-like body-attachable thermometer. Compared to the polymer substrate, the use of hydrophilic and flexible paper substrate facilitates significantly superior sensitivity and simple fabrication. The paper sensor is fabricated by depositing PEDOT:PSS onto the paper with an 80 g base weight for 40 s, which is covered with a 50 μm film to protect it from humidity. This is followed by a heat treatment at 150 °C for 10 min. The paper sensor exhibited an electrical conductivity of 0.48 Ωcm−1 at room temperature with a linearity of 99.86 %. Remarkably, its sensitivity is 658.5 Ω/°C, which is 14 times higher than that of sensor with polyimide substrate (46 Ω/°C), for the body temperature range of 30–42 °C. The paper-based temperature sensor is implemented in a body-attachable patch for a wearable thermometer, which is simply connected with a circuit part for signal processing and the results are transferred to a phone via Bluetooth. The proposed inexpensive sensor is potentially useful for a wide range of flexible electronics and healthcare applications. [ABSTRACT FROM AUTHOR]

A previous paper published in this journal proposed a model for evaluating the location of fingermarks on two-dimensional items (de Ronde, van Aken, de Puit and de Poot (2019)). In this paper, we apply the proposed model to a dataset consisting of letters to test whether the activity of writing a letter can be distinguished from the alternative activity of reading a letter based on the location of the fingermarks on the letters. An experiment was conducted in which participants were asked to read a letter and write a letter as separate activities on A4- and A5-sized papers. The fingermarks on the letters were visualized, and the resulting images were transformed into grid representations. A binary classification model was used to classify the letters into the activities of reading and writing based on the location of the fingermarks in the grid representations. Furthermore, the limitations of the model were studied by testing the influence of the length of the letter, the right- or left-handedness of the donor and the size of the paper with an additional activity of folding the paper. The results show that the model can predict the activities of reading or writing a letter based on the fingermark locations on A4-sized letters of right-handed donors with 98 % accuracy. Additionally, the length of the written letter and the handedness of the donor did not influence the performance of the classification model. Changing the size of the letters and adding an activity of folding the paper after writing on it decreased the model's accuracy. Expanding the training set with part of this new set had a positive influence on the model's accuracy. The results demonstrate that the model proposed by de Ronde, van Aken, de Puit and de Poot (2019) can indeed be applied to other two-dimensional items on which the disputed activities would be expected to lead to different fingermark locations. Moreover, we show that the location of fingermarks on letters provides valuable information about the activity that is carried out. [ABSTRACT FROM AUTHOR]

In accordance with global estimations, approx. 15 million tons of residues are yearly generated from paper and pulp industry, which are traditionally used as biofuels or just disposed in landfills. However, residues composition and laws in force urge producers to search for new waste management strategies. From another point of view, the construction industry uses more than 33% of total natural resources, worldwide which has led several governments to limit the use of natural raw materials for building. In particular, fired brick industry produces yearly approx. 1600 billion bricks which represents millions of tons of natural resources consumption. Therefore, the goal is to contribute to reduce the amount of used clay. Thus, this paper explores the mineral and technological properties of brick made by using different percentages of paper pulp residues and fired at 900 °C. Results indicate that by increasing the replacement ratio, blend requires larger amounts of water which leads to a proportional increasing of shrinkage during drying. In spite of mineral transformations are not influenced by paper pulp residue, the porosity is linearly increased which leads to reduce compressive strength and thermal conductivity up to 30% for 20% of replacement ratio, in both cases. Thus, it is concluded that series made by replacing up to 10% show compressive strength above 5 MPa, water absorption beyond 20% and toxicity indexes meet the mandatory requirements. [ABSTRACT FROM AUTHOR]

• MNFC preparation by chemo-refining route - potential to implement in paper industry. • Pretreatment with sodium meta-periodate and sodium chlorite followed by refining. • Nano and micro range fibres with improved WRV and carboxylic content. • Improved paper properties after MNFC addition without lowering pulp drainability. Micro-nanofibrillated cellulose was prepared using bleached mixed hardwood pulp by a low energy consuming chemo-refining approach having potential to be implemented easily in paper industry. Bleached mixed hardwood pulp was pretreated with sodium meta-periodate and sodium chlorite and micro-nanofibrillated by using refining in Valley beater. Scanning electron microscopy images of prepared micro-nanofibrillated cellulose showed 87 % fibre distribution in nano range, 4.47 ± 0.5 g/g water retention value and 2.13 ± 0.1 meq/100 g carboxyl content. Carboxylation effect of given chemical pretreatment was further confirmed by FTIR analysis. Paper handsheets, having bleached mixed hardwood pulp and prepared micro-nano-fibrillated cellulose, resulted in about 5% lower bulk with 27 %, 32 % and 87 % higher breaking length, burst factor and double fold, respectively than control (without nano-fibrillated cellulose). Prepared micro-nanofibrillated cellulose addition didn't show negative effect on pulp drainability (33 °SR). This work showed that micro-nanofibrillated cellulose might also be prepared using conventional routes of paper industry to improve paper properties. [ABSTRACT FROM AUTHOR]

• We introduce a colorimetric and SERS sensor for the dual-mode detection of H 2 S. • A simple and facile H 2 S assay was prepared by dropping of Ag nanoplate solution on paper. • We utilized the parameter b of CIE L*a*b color model for the quantitative color analysis. • The analytical performance of H 2 S sensing paper for dual-mode detection was evaluated. • This paper assay can detect endogenous H 2 S in live LNCaP cells under shorter incubation times. We report a simple and facile paper assay based on silver nanoplates (Ag NPls) for the colorimetric and surface-enhanced Raman scattering (SERS) dual-mode detection of hydrogen sulfide (H 2 S) gas released from live cancer cells. Ag NPls were prepared via seed-mediated growth and dropped on detection zones within the poly(dimethylsiloxane)-patterned paper substrate. The blue-colored Ag NPls on the paper react with H 2 S to form brown-colored silver sulfide, which simultaneously decreases SERS activity of Ag NPls. We quantitatively analyzed the color and Raman signal intensity changes in Ag NPl-coated detection zone on the paper, using the parameter b of L*a*b color space and Raman peak at 1356 cm−1 of Rhodamine B, respectively. As a result, our Ag NPl-coated H 2 S dual-sensing paper assay showed a good sensitivity with a linear range of 1.64–16.4 μM H 2 S and a detection limit of 520 nM for colorimetric detection. And, it also represented a high sensitivity with a linear range of 82–330 nM H 2 S for SERS detection. In addition, it possessed high selectivity, excellent reproducibility, and high stability over 1 month. Using this Ag NPl-coated H 2 S dual sensing paper, we successfully measured the H 2 S concentration in live prostate cancer cells at different incubation times and cell numbers. Therefore, the Ag NPl-coated paper assay can be utilized as a facile and effective tool for the dual-mode colorimetric and SERS detection of free H 2 S gas within live cells without complicated sample processing or labor-intensive bioanalytical methods. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Newly developed active pharmaceutical ingredients (API) often experience low solubility in aqueous media and thus possess poor oral bioavailability. The SmartFilm®-technology is a novel approach to overcome poor solubility. The technique uses commercial paper in which API can be loaded in amorphous state, thus increasing dissolution rate dc/dt and solubility c s when compared to bulk material. However, the preservation of the amorphous state is a prerequisite for an efficient use of the smartFilm-technology and thus the crystalline state needs to be inspected during storage. Preferably, this should be done non-destructively. Traditional techniques, such as x-ray diffraction (XRD) or differential scanning calorimetry (DSC), do not allow for non-destructive crystallinity investigations, whereas Terahertz (THz) spectroscopy is a non-destructive technique, that is sensitive to the crystalline state of many molecular crystals. Therefore, the potential of THz-spectroscopy for crystallinity state inspection of API in smartFilms and tablets made from smartFilms was investigated in this study. The THz results obtained were compared to results obtained from XRD and DSC measurements. Whereas DSC measurements failed to reliably detect crystalline API in the smartFilms, XRD and THz-spectroscopy showed similar results and revealed that it was possible to prepare smartFilms loaded with >23% (w/w) amorphous API. Results indicate the great potential of THz spectroscopy for the non-destructive determination of the crystalline state of APIs in smartFilms and/or tablets made from paper. [ABSTRACT FROM AUTHOR]

• Overall, synergism was observed across all temperature ranges (25–52 °C). • PC can be used for VFA production at temperature of ≥42 °C. • Optimized temperature for PWC, FWC and OFMSW were 52, 37 and 42 °C respectively. • Mainly, acetic and butyric acids were produced from PC at 52 °C and FC at 37 °C. This study explores individual contributions and synergistic effects of food and paper, main components of organic fraction of municipal solid waste (OFMSW) towards volatile fatty acids (VFA) fermentation under different temperatures (25, 37, 42 and 52 °C). Thanks to the synergism of food and paper component (FC & PC), the results revealed that OFMSW is suitable for VFA production. Maximum VFA production was noticed to be 21.5 mg/L at 42 °C, ~2.1, and 1.42 times higher than fermentation of PC and FC. Enhanced hydrolysis of PC occurred at >37 °C, increasing alkalinity in leachate to 6.7 g/L at 42 °C, thus maintaining a stable pH (5.4–5.6) during acidogenic fermentation. Additionally, 74% of COD is hydrolyzed, of which 79% is converted to VFA based on biodegradable carbon at 42 °C. It is suggested that co-existence of FC and PC can enhance VFA production of OFMSW, and targeted VFA production can be maximized through process optimization. [ABSTRACT FROM AUTHOR]

We investigated the electrochemical performance of reduced graphene oxide (rGO)/carbon nanotube (CNT) hybrid papers as binder-free anodes for potassium-ion batteries. RGO/CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. The potassium-ion storage ability of rGO paper was significantly enhanced by CNT incorporation and the electrochemical performance of the hybrid papers was related to the weight ratio of CNTs. The optimal rGO/CNT-30% paper can deliver an initial reversible discharge capacity of 351 and 223 mA h g−1 at a current density of 10 and 50 mA g−1, respectively. A capacity of 148 mA h g−1 was achieved after 200 cycles at a current density of 50 mA g−1. The enhanced performance of rGO/CNT hybrid papers is attributed to the formation of a 3D conductive carbon network, in which the graphene layers are bridged by CNTs. Such a structure could effectively facilitate the transport of electrons and potassium ions and provide more storage sites for potassium ions. Image 1 • RGO/CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. • The potassium-ion storage ability of rGO paper was significantly enhanced by CNT incorporation. • RGO/CNT-30% paper delivered a reversible capacity of 232 mA h g−1 at a current density of 50 mA g−1, respectively. • The enhanced performance of rGO/CNT hybrid papers was attributed to the formation of a 3D conductive carbon network. [ABSTRACT FROM AUTHOR]

• Waste paper was used to obtain nanocrystalline cellulose (CNC). • The obtained CNC was compared with CNC from cotton linter. • The biocidal activity of CNC added with Ag nanoparticles was assessed. • The growth of Aspergillus niger on Whatman paper is inhibited by CNC/Ag coating. • The mechanical properties of Whatman paper improve by the CNC coatings. Waste paper is an environmentally friendly source of cellulosic material. Here we propose a new treatment based on nanocrystalline cellulose (CNC) for paper preservation and consolidation. Suspensions of CNC were prepared by sulfuric acid hydrolysis using waste paper as cellulose source (CNC WP) and compared with CNC from cotton linter (CNC CL). Both CNCs were obtained with good yield, showing high crystallinity index and comparable morphology, as demonstrated by DLS-ELS, XRD, FTIR, Raman and TEM analyses. CNCs were mixed with silver nanoparticles (CNC/Ag) and their biocidal activity was tested against Escherichia coli and Bacillus subtilis , measuring the minimum inhibitory concentration. CNCs were exploited as treatments for biocidal activity and consolidation on Whatman paper. The presence of silver nanoparticles doesn't affect aesthetic appearance of the original paper and prevents the growth of Aspergillus niger fungus. Mechanical tests demonstrated that the coatings by CNC based products improve stretch and toughness of the paper support. [ABSTRACT FROM AUTHOR]

• Ultrasensitive detection limit can reach as low as 0.01 ppm for riboflavin. • Just need a single droplet for detection using this indicator paper. • In-situ dual detection of riboflavin and pH with same droplet and indicator paper. • Excellent self-clean property makes droplet easy to remove and brings recyclability. Traditional indicator paper is disposable after use, requires a large number of target solutions and can only detect one item. In this study, recyclable upconversion-fluorescence indicator papers consist of upconversion nanorods and plasmonic nanostructures are fabricated by electrospinning. Human-body fluids containing different riboflavin concentration and pH are used as target solution, because these two items are usually detected in clinic to distinguish ambiguous diseases but often performed by two different testing processes that inevitably need more target solutions. Significantly different from conventional detecting system, this recyclable indicator paper can simultaneously achieve riboflavin and pH detections by using only a single droplet of target solution. As low as 0.01 ppm riboflavin can be sensitively detected, which is superior to most reported detection limit of fluorescence sensor. Moreover, this indicator paper can detect a single droplet (~10 μl) rather than a large amount of target solution (>1 ml) needed by traditional detecting system, and the pH can also be simultaneously in-situ detected using the same indicator paper. After the detection, the target solution is easily removed so that it brings about excellent recyclability, which is another advantage over traditional detecting system. [ABSTRACT FROM AUTHOR]

Abnormal expression of MicroRNA-21 (miRNA-21) is considered to be a reliable biomarker for the early diagnosis of cancer. In this work, a novel paper based biosensor was fabricated to detect sub-micro molar concentrations of miRNA-21 based on peroxidase mimetic activity of DNA-templated Ag/Pt nanoclusters (DNA-Ag/Pt NCs), which could catalyze the reaction of hydrogen peroxide and 3,3′,5,5′ tetramethylbenzidine (TMB), to produce a blue color. The Mechanism of reaction was based on the inhibition effect of miRNA-21 on peroxidase-like activity of nanosensor which resulted to quantitative determination of miRNA-21 concentration. It was found that miRNA-21 could be linearly detected in the range from 1-700 pM (A 652 = 0.16x-0.96, R2 = 0.99; x = -log [miRNA-21]) with a detection limit of 0.6 pM. Moreover, a paper assay was carried out on a Y-shaped paper-based microfluidic device in order to use the distinctive features of micro-channels such as short response time, very low reagent volume, low fabrication cost, etc. After performing paper based assay, a good linear range was observed between 10-1000 pM (y = 0.06x+147.48, R2 = 0.99; x = [miRNA-21]) with detection limit of 4.1 pM. The practical application of proposed method for detection of miRNA-21 in real sample was assayed in the human urine sample and indicated the colorimetric method had acceptable accuracy. Image 1 • A novel paper-based microfluidic sensor was designed for detection of miRNA-21. • The miRNA-21 detection mechanism is based on peroxidase mimetic activity of DNA-Ag/Pt NCs. • The color change was obvioused in different concentration of miRNA-21. • This strategy shows excellent selectivity toward miR-21. [ABSTRACT FROM AUTHOR]

• Application of barrier dispersion to linerboard by the flexography was demonstrated. • Drying at temperature higher than 40 °C is required to improve barrier performance. • Insufficient drying creates cracks providing open pathways for moisture penetration. • DMTA shows that higher curing temperature improves film uniformity and stiffness. We demonstrate the use of tetraethylorthosilicate (TEOS) as a silica precursor for water barrier poly(styrene-butadiene) latex dispersion coating applications. The TEOS is adsorbed at the surface interface by the latex particles in the aqueous dispersion due to the hydrophobic nature of the surface and the TEOS. It then undergoes hydrolysis and condensation to the silica phase in the interstitial sites in the partially dry close-packed polymer structure. The fully cured film exhibits a greater degree of coalescence than films prepared from the unmodified latex binder. Large discrete silica particles are not formed within the cured film; rather the films contain homogenous silica dispersion with a probable particle size no larger than 10 nm. This higher degree of coalescence results in improvements in water vapour barrier performance from 121 – 20 g m−2 d−1, with direct water barrier performance (Cobb 120 s) improving from 25 to < 2 g m−2, compared to the silica-free film. [ABSTRACT FROM AUTHOR]

Aramid fibers exhibit impressive mechanical properties, electrical insulation properties, and chemical stability. However, physical properties of the aramid paper are poor because of the chemical inertness and smooth surface of aramid fibers. This study reports a simple and efficient method for substantially improving the performance of the para-aramid/meta-aramid composite paper by introducing the N , N -dimethylacetamide (DMAc)/LiCl solution to induce partial dissolution or by adding the DMAc/LiCl/para-aramid solution to induce regeneration. Experimental results state that the tensile strength, specific strength, folding resistance, and interlayer bonding strength of the aramid paper are increased by 2.17, 2.13, 34.7, and 9.39 times, respectively, because of the dense and compact structure of the paper. Furthermore, the water resistance of the paper was also considerably improved. After immersing the paper samples in water for 24 h, their moisture absorption rate decreased to approximately 54% from approximately 143% for the original paper. Results indicate that partial dissolution/regeneration welding is a viable method for the efficient reinforcement of the aramid composite paper, providing additional possibilities for manufacturing the high-performance aramid paper-based materials. Unlabelled Image • The para-aramid/meta-aramid composite papers, exhibiting amazing mechanical strengths, were obtained. • The performance of the para-aramid/meta-aramid composite paper was improved by adding N , N -dimethylacetamide/LiCl solution. • The moisture absorption of aramid composite paper decreased from approximately 143% for the original paper to approximately 54%. [ABSTRACT FROM AUTHOR]

ZnO thin films were deposited on paper substrates by radio frequency magnetron sputtering at room temperature. By appropriate controlling the sputtering pressure, highly oriented (002) ZnO film with large grain size and low defect density can be obtained. Metal-semiconductor-metal structure ultraviolet photodetectors (UVPDs) were fabricated based on the ZnO/paper films and their optoelectronic response properties were investigated in detail. The optimum UVPD exhibits high UV sensitivity, showing peak responsivity at 380 nm. At applied voltage of 10 V, the UVPD has a high responsivity of 0.86 A/W and a high on/off ratio of ~600. Moreover, the flexible UVPD exhibits excellent stability and reproducibility under different bending conditions. The high flexibility of the UVPD was attributed to the compact and continuous properties of the sputtered film. The excellent operating characteristics make the UVPD a potential candidate for wearable UV meters and communication devices. • Paper based ultraviolet photodetector exhibits high flexibility and stability. • The paper substrate is renewable, biodegradable and abundant. • ZnO film was grown on paper at room temperature by magnetron sputtering. • Highly oriented (002) ZnO film was prepared with appropriate sputtering pressure. [ABSTRACT FROM AUTHOR]

Contact with thermal printing paper is a relevant source of dermal exposure to unbonded bisphenol A (BPA). In order to limit this exposure route, the European Union has introduced a drastic reduction in the maximum allowed concentration of BPA in thermal paper produced after beginning of year 2020. This study investigates the suitability of direct analysis in real time (DART), combined with accurate mass spectrometry, as a faster alternative to chromatography-based methods for the quantitative determination of BPA, and three analogues species, in receipts and tickets usually printed on thermal paper. The ionization efficiency of these compounds is evaluated under different conditions, and the effect of instrumental parameters of the DART source in the observed responses is discussed. The yield of the DART desorption-ionization process was greatly improved when compounds are previously converted into their acetyl derivatives; thereafter, the temperature of electronically excited helium atoms was the most relevant of the evaluated instrumental parameters. Under optimized conditions, the reported method provided recoveries in the range from 90 to 110%, a limit of quantification of 0.004% (w:w), well below the maximum concentration established after 2020 for BPA (0.02%, w:w), and permitted to perform duplicate determinations of each sample extract with a response time around 1 min. The accuracy of BPA levels found in non-spiked samples was confirmed using GC-EI-MS as reference technique. BPA was systematically noticed in the processed samples with concentrations ranging from 0.005% to more than 6%. Image 1 • Rapid determination of bisphenol A in thermal printing paper by DART accurate MS. • Acetylation greatly enhances the yield of DART desorption-ionization. • Procedural LOQs below limits set for bisphenol A in thermal paper. • Good correlation between DART-MS and GC-EI-MS values in thermal paper samples. [ABSTRACT FROM AUTHOR]

• RGHC generated intense shear rates and a violent form of developed cavitation. • The RGHC is successful at refining pulp with the usual consistency of 3%. • The physical properties of produced paper sheets were similar to newsprint paper. • Cavitation proved to be more economical in comparison to a Valley beater. Refining of cellulose pulp is a critical step in obtaining high quality paper characteristics, however, this process is slow and costly especially for refining longer conifer fibers which are the preferred source for high quality paper production and give the paper its strength. In this study, we have applied a novel rotation generator of hydrodynamic cavitation for refining conifer rich pulp samples. Our results show that the device is capable of generating intense shear forces and multiple zones of developed cavitation and is successful in increasing the drainage rate of high consistency pulp (3%). The paper produced by means of the obtained pulp has higher quality because of its higher tensile index (50.5 kN m kg−1) and burst index (3 kPa m2 g−1). These physical parameters were sufficient for newsprint paper and other paper/board quality manufacture. In addition, this laboratory scale rotation generator proved to be economically efficient in comparison to the routinely employed laboratory beaters. To our knowledge, this is the first example of using hydrodynamic cavitation for the refinement of softwood fiber pulp of standard industrial consistencies (3%). [ABSTRACT FROM AUTHOR]

There have been several cases in the news regarding the presence of synthetic cannabinoids on paper being smuggled into jails and prisons in the United States. The Allegheny County Office of the Medical Examiner has been involved in the analysis of multiple cases. For the first time the laboratory received an analysis request for not only identification of controlled substances, but also for the presence of latent fingerprints. It was unknown if the processing methods used by the latent print unit would interfere with the identification of the controlled substances. This paper shows that DFO and ninhydrin processing will remove some of the synthetic cannabinoids, possibly effecting concentration on the paper, but the substances were still able to be positively identified after processing. [ABSTRACT FROM AUTHOR]

A robust superhydrophobic ZnO coating on a filter paper substrate was successfully prepared for the first time by using a successive deposition process and chemical modification. The surface morphology, chemical composition, wetting property, mechanical stability, chemical stability and durability of the filter papers were examined. The as-prepared papers exhibited an improved rough surface topography compared with the uncoated paper due to the uniform ZnO microclusters decorated on the reticular fibers. More importantly, it was found that the wettability of papers was dependent on the surface roughness, which was governed by the number of ZnO microcluster deposition cycles. After the chemical modification with stearic acid, the resulting paper with 4 cycles presented the optimized superhydrophobicity with a water contact angle (WCA) of 158°, a slide angle (SA) of 3°, a low adhesion and good bounce performance. The chemical resistance of the superhydrophobic paper to corrosive liquids was studied. Moreover, the superhydrophobicity of paper was not affected after the water drops impact test or it was kept for 6 months, indicating its high impact resistance and long-term stability. The excellent superhydrophobicity of paper can be attributed to the synergistic effect of the suitable micro/nanoscale hierarchical roughness and the low surface energy modification. Unlabelled Image • A novel superhydrophobic paper modified with ZnO microclusters was fabricated. • The resulting paper presented the optimized superhydrophobicity, good bounce performance, and high impact resistance. • The superhydrophobicity is attributed to suitable micro/nanoscale hierarchical roughness and low surface energy modification. [ABSTRACT FROM AUTHOR]

Paper-based diagnostic assay is quite popular in point-of-care testing (POCT). In this work, we reported a series of hybrid fluorophores based on fluorescein derivatives and investigated their fluorescent properties in detail. To extend the practical application of these hybrid fluorophores, we further constructed the corresponding probes (FN1-FN4) for Cu2+ detection. In comparison with the other three probes, FN4 showed high selectivity and sensitivity, as well as response to Cu2+ within 20 min. Particularly, by introducing this probe into the paper-based device, we could achieve simple, high-throughput, visual and highly sensitive platform for POC detection of Cu2+. Finally, we assessed the paper-based device in real samples such as serum, cytochylema and lake water to demonstrate its promising application. As a result, satisfied performance for Cu2+ detection was achieved, which indicates the great potential of our strategy in the construction of POCT system for detecting analytes. Image 1 • Novel hybrid fluorophores based naphthofulorescein dyes have been synthesized to show excellent fluorescence properties. • Hybrid fluorophores-based paper device for visual detection of Cu2+ has been developed. • Suitable for point-of-care detection, the paper device could visualize high-throughput Cu2+ detection in real samples. [ABSTRACT FROM AUTHOR]

(E)-Stilbene hydrophobic fluorophores possessing long perfluorinated or hydrocarbonated chains have been prepared through a stereoselective Wittig-Schlosser reaction. When covalently grafted upon paper, they give rise to a fluorescent-labeled paper upon irradiation with UV light. The hydrophobicity and oleophobicity of the fluorous (E)-stilbene derivative furnish self-cleaning properties. Application in the detection of money counterfeiting is envisioned. Image 1 • A new family of fluorescent (E)-stilbene derivatives have been prepared in a real simple and straightforward way. • The fluorescent (E)-stilbene derivatives were covalently grafted upon paper giving rise to a photochromic paper. • The hydrophobicity and oleophobicity of the fluorous (E)-stilbene derivative furnish self-cleaning properties. • This approach can have a real application in the detection of counterfeited paper money. [ABSTRACT FROM AUTHOR]

Tricolor emissive CDs with multiple-cores@shell structure were synthesized by one-pot hydrothermal route. The surface Aphen moieties endow the as-synthesized AC-CDs with promising pH-sensitive function to prepare fluorescent pH test paper towards qualitative and quantitative detection of pH in the solution. CDs can be used as a cell imaging marker and efficient cellular labelling to detect intracellular pH due to its unique tricolor emission property. • Tricolor emissive CDs with multiple-cores@shell structure were synthesized by one-pot hydrothermal route. • The as-obtained CDs were used to prepare fluorescent pH test paper with promising pH-sensitive feature. • CDs can be used as a cell imaging marker and efficient cellular labelling to detect intracellular pH. • Unique tricolor property of CDs can avoid the fluorescent dyes and protein fluorescence interference for cell imaging. Recently, fluorescent pH test paper has been extensively explored for visual assays due to its easy preparation, low-cost, and portable feature. In addition, intracellular pH also plays important roles in different pathological and physiological processes for understanding cellular functions and providing critical assistance for early disease diagnosis. Herein, the tricolor emission multiple-cores@shell carbon dots (CDs) were synthesized via one-pot hydrothermal method using 5-amino-1,10-phenanthroline (Aphen) and citric acid (CA) as the carbon sources. The fluorescence emission of CDs showed an interesting pH dependence due to the special structure and properties, which can make the CDs to be used as the pH test paper to qualitatively and quantitatively detect pH value in a wide pH range. At the same time, because of good cell compatibility and low toxicity, CDs can be used as a new type of cell imaging marker to detect intracellular pH. The unique tricolor emission property of CDs can well avoid the fluorescent dyes and protein fluorescence interference. [ABSTRACT FROM AUTHOR]

• Hydrogen bonds formed in the LTTMs enabled the removal of lignin from EFB. • Clear separation of precipitated lignin was observed in EFB strands after washing. • EFB powder showed stronger molecular bonding of pulp than EFB strands. • Paper formed from cactus based LTTMs-delignified EFB had less void space and pores. The aim of this work was to recover the cellulose fibers from EFB using low-transition-temperature-mixtures (LTTMs) as a green delignification approach. The hydrogen bonding of LTTMs observed in 1H NMR tends to disrupt the three-dimensional structure of lignin and further remove the lignin from EFB. Delignification process of EFB strands and EFB powder were performed using standard l -malic acid and cactus malic acid-LTTMs. The recovered cactus malic acid-LTTMs showed higher glucose concentration of 8.07 mg/mL than the recovered l -malic acid LTTMs (4.15 mg/mL). This implies that cactus malic acid-LTTMs had higher delignification efficiency which led to higher amount of cellulose hydrolyzed into glucose. The cactus malic acid-LTTMs-delignified EFB was the most feasible fibers for making paper due to its lowest kappa number of 69.84. The LTTMs-delignified EFB has great potential to be used for making specialty papers in pulp and paper industry. [ABSTRACT FROM AUTHOR]