Search

Aromatic sensitizers and related substances (SRCs), which are crucial in the paper industry for facilitating color‐forming and color‐developing chemical reactions, inadvertently contaminate effluents during paper recycling. Owing to their structural resemblance to endocrine‐disrupting aromatic organic compounds, concerns have arisen about potential adverse effects on aquatic organisms. We focused on SRC effects via the aryl hydrocarbon receptor (AHR), employing molecular docking simulations and zebrafish (Danio rerio) embryo exposure assessments. Molecular docking revealed heightened binding affinities between certain SRCs in the paper recycling effluents and zebrafish Ahr2 and human AHR, which are pivotal components in the SRC toxicity mechanism. Fertilized zebrafish eggs were exposed to SRCs for up to 96 h post fertilization; among these substances, benzyl 2‐naphthyl ether (BNE) caused morphological abnormalities, such as pericardial edema and shortened body length, at relatively low concentrations (1 μM) during embryogenesis. Gene expression of cytochrome P450 1A (cyp1a) and ahr2 was also significantly increased by BNE. Co‐exposure to the AHR antagonist CH‐223191 only partially mitigated BNE's phenotypic effects, despite the effects of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin being relatively well restored by CH‐223191, indicating BNE's AHR‐independent toxic mechanisms. Furthermore, some SRCs, including BNE, exhibited in silico binding affinity to the estrogen receptor and upregulation of cyp19a1b gene expression. Therefore, additional insights into the toxicity of SRCs and their mechanisms are essential. The present results provide important information on SRCs and other papermaking chemicals that could help minimize the environmental impact of the paper industry. Environ Toxicol Chem 2024;00:1–13. © 2024 SETAC [ABSTRACT FROM AUTHOR]

Capturing short‐lived intermediates at the molecular level is key to understanding the mechanism and dynamics of chemical reactions. Here, we have developed a paper‐in‐tip bipolar electrolytic electrospray mass spectrometry platform, in which a piece of triangular conductive paper incorporated into a plastic pipette tip serves not only as an electrospray emitter but also as a bipolar electrode (BPE), thus triggering both electrospray and electrolysis simultaneously upon application of a high voltage. The bipolar electrolysis induces a pair of redox reactions on both sides of BPE, enabling both electro‐oxidation and electro‐reduction processes regardless of the positive or negative ion mode, thus facilitating access to complementary structural information for mechanism elucidation. Our method enables real‐time monitoring of transient intermediates (such as N,N‐dimethylaniline radical cation, dopamine o‐quinone (DAQ) and sulfenic acid with half‐lives ranging from microseconds to minutes) and transient processes (such as DAQ cyclization with a rate constant of 0.15 s−1). This platform also provides key insights into electrocatalytic reactions such as Fe (III)‐catalyzed dopamine oxidation to quinone species at physiological pH for neuromelanin formation. [ABSTRACT FROM AUTHOR]

Herein, a new, direct paper-based fluorimetric method is described for the quantitative determination of glutathione (GSH) molecules in nutritional supplements. Briefly, the proposed analytical method is based on the fluorescence emission resulting from the direct and selective chemical reaction of GSH molecules with the derivatization reagent that is o-phthalaldehyde (OPA) in acidic conditions at room temperature. The intensity of the emitted fluorescence on the surface of the analytical paper devices after irradiation with a lamp at 365 nm is proportional to the concentration of GSH and is measured using a smartphone as the detector. This methodology, which is suitable for measurements in laboratories with limited resources, does not require specialized instrumentation or trained personnel. The protocol governing the proposed method is simple and easily applicable. Essentially, the chemical analyst should adjust the value of pH on the surface of the paper by adding a minimal amount of buffer solution; then, after adding a few microliters of the derivatization reagent, wait for the surface of the paper to dry and, finally, add the analyte. Subsequently, the irradiation of the sensor and the measurement of the emitted fluorescence can be recorded with a mobile phone. In the present study, several parameters affecting the chemical reaction and the emitted fluorescence were optimized, the effect of interfering compounds that may be present in dietary supplements was examined, and the stability of these paper sensors under different storage conditions was evaluated. Additionally, the chemical stability of these paper devices in various maintenance conditions was studied, with satisfactory results. The detection limit calculated as 3.3 S/N was 20.5 μmol L−1, while the precision of the method was satisfactory, ranging from 3.1% (intra-day) to 7.3% (inter-day). Finally, the method was successfully applied to three different samples of dietary supplements. [ABSTRACT FROM AUTHOR]

Enhancing paper hydrophobicity is of key importance for many paper-based applications. Fatty acids or vegetable oils and their derivatives replace environmentally harmful conventional coating materials but still require challenging chemical reactions for covalent attachment onto paper. Here, we show that simple storage of olive oil-coated cotton linter paper at 70 °C and subsequent Soxhlet extraction is able to endow paper with hydrophobic properties, reaching water contact angles above 130°. In-depth chemical and morphological analytics show the relevance of temperature and air accessibility during the aging process compared with aging at ambient temperature and under the exclusion of oxygen, underlining the importance of assessing a coating's long-term performance and stability under diverse storage conditions. Simple storage of vegetable oil-coated paper at elevated temperatures followed by extraction proves to be an easy way to produce stable covalently attached hydrophobic paper coatings with exceptionally low coating amounts. [ABSTRACT FROM AUTHOR]

• Filter paper was selected as the template for synthesis of 1D NiO/NiCo 2 O 4 composite. • Ultra simple synthetic procedures of only metal salts adsorption and calcination was referred. • The effective bandwidth is up to 6.08 GHz at thin thickness of 1.88 mm. Filter paper, as a widely used and low-cost lab consumable, can serve as template for the synthesis of one-dimensional (1D) materials since it is composed of 1D cellulosic fiber. In this work, 1D NiO/NiCo 2 O 4 composite was simply fabricated by adsorption of Ni and Co acetate on the filter paper and subsequent calcination process. The precursors were obtained without further treatment to filter paper or chemical reaction between metal salts. Calcination process leads to the removal of template and formation of binary NiO/NiCo 2 O 4 composite. Electromagnetic (EM) wave absorption performance of NiO/NiCo 2 O 4 composite could be tuned by adjusting the calcination temperatures and dosage of metal salts. For the optimized absorber (calcination temperature of 600 °C and dosage of Ni and Co acetate with 2 mmol and 4 mmol), a wide absorption bandwidth of 6.08 GHz could be achieved with thickness of 1.88 mm and minimum reflection loss value was up to −57.4 dB by changing the thickness. The facile synthetic route may also inspire the preparation of other high-performance one-dimensional EM wave absorbing materials. [ABSTRACT FROM AUTHOR]

The pigment coating of paper is usually performed to enhance the physical properties of paper and its printability. The coating generally makes paper whiter, brighter and more opaque. The properties of the coated paper depend, among others, on the porous structure of the coating developed, which is determined by the pigments, binders and their reactions. The influence of the type and quantity of coating components and ink absorption into the coating layer was studied in this work. Printing ink penetration was measured using a Penetration Dynamic Analyser with a HVL module (High Viscous Liquid). The evenness of liquid penetration into paper was measured using a Penetration Dynamic Analyser with a PEA module (Print Evenness Analyser). Results obtained indicate that all three variables - coating pigment type, latex dose and ink type - may have an equally strong influence on liquid and ink penetration, and thus on print quality. [ABSTRACT FROM AUTHOR]

High‐barrier performance, especially under extreme working conditions, is the key to replacing other types of packaging materials with paper‐based materials. In this paper, two biomass‐based polymers, sodium alginate (SA), and chitosan, were used to form a barrier coating with silicone emulsions to prepare a high‐performance paper‐based barrier material. By double coating, the water and oilproof functions were superimposed. The two prepared coated papers were characterized by infrared spectroscopy analysis, contact angle test, and scanning electron microscopy analysis, while their water resistance, oil resistance, thermal oil resistance, and thermal stability were tested. The water and oil repellency were achieved by double coating. The Cobb value of the chitosan‐silicone emulsion‐coated paper reached 5.3 g/m2, with a Kit grade of Level 12, and could block the penetration of castor oil at 80°C within 24 h. The Cobb value of the sodium alginate‐silicone emulsion‐coated paper was 41.6 g/m2, much higher than that of the uncoated paper, with a Kit grade of up to Level 10, which could slow down the rate of castor oil penetration at 80°C within 24 h. The test results showed that there was no chemical reaction between the paper‐based coatings, and the coated paper surface had good film formation, while the double coating method increased the thermal decomposition temperature of the overall barrier coating, effectively improving the thermal stability of the coating and achieving high‐barrier performance at lower cost and under extreme working conditions. Highlights: Water and oil resistance under extreme operating conditions.High‐performance paper‐based barrier materials.Dual‐layer coating method for water and oil repellency.High‐barrier performance at lower cost.Excellent hot oil resistance and thermal stability. [ABSTRACT FROM AUTHOR]

Milk is considered a complete meal that requires supervision to determine its suitability for human consumption. The development of sustainable devices that evaluate food properties has gained importance due to the necessity of integrating these instruments into the production chain. However, the materials employed to develop it, such as polymers, semiconductors, and glass, lack sustainability and require specialized equipment to fabricate them. Different chemical techniques have been used to miniaturize these detection systems such as microfluidics, which have been used in milk component detection using colorimetry. In this work, a cantilever beam paper-based microfluidic system is proposed to evaluate differences in milk, according to nutritional information, using its electromechanical response. A 20-microliter milk drop is deposited in the system, which induces hygroexpansion and deflection due to liquid transport within the paper. Likewise, a conductive path is added on the beam top surface to supply a constant current that induces heat to evaporate the solution. According to the results obtained, it is possible to point out differences between trademarks with this microfluidic system. The novelty of this system relies on the paper electromechanical response that integrates the hygroexpansion-induced displacement, which can be used for further applications such as milk microtesters instead of colorimetric tests that use paper as a property-evaluation platform in combination with chemical reactions. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray (PS) is a simple and innovative ambient ionization technique for mass spectrometry (MS) analysis. Under PS‐MS conditions, chemical reactions, which usually occur slowly on a bulk scale, are accelerated. Moreover, the formation of products and transient species can be easily monitored. In this manuscript, reactions between phthalic anhydride and diamines were conducted and monitored using a PS‐MS platform. The reaction products (phthalimides) have many pharmaceutical applications, but their traditional syntheses can take hours under reflux, requiring laborious purification steps. Methods: In situ reactions were performed by dropping methanolic solutions of phthalic anhydride and diamines on a triangular paper. The analyses were achieved by positioning the triangle tip in front of the mass spectrometer entrance, whereas a metal clip was attached to the triangle base. After adding methanol to the paper, a high voltage was applied across the metal clip, and the mass spectra were acquired. Results: The intrinsic reactivity of alkyl and aromatic diamines was evaluated. The carbon chain remarkably influenced the reactivity of aliphatic diamines. For aryl diamines, the ortho isomer was the most reactive. Moreover, for aryl amines with electron‐withdrawing substituents, no reaction was noticed. Conclusions: Taking advantage of the unique characteristics of PS‐MS, it was possible to investigate the intrinsic reactivity of model alkyl (ethylene versus propylene) and aryl (o‐phenylene versus m‐phenylene and p‐phenylene) diamines towards phthalic anhydride. Some crucial parameters that affect the intrinsic reactivity of organic molecules, such as isomerism, intramolecular interaction, and conformation, were easily explored. [ABSTRACT FROM AUTHOR]

With the implementation of plastic restrictions and the increasingly serious problem of environmental pollution, paper with green and recyclable characteristics is gradually becoming a substitute for packaging materials. However, the rich cellulose structure in the paper, which contains hydroxyl groups leading to its hydrophilicity, allows water molecules to penetrate the paper and disrupt the hydrogen bonds between cellulose, resulting in a decrease in mechanical properties. Therefore, waterproof coatings are crucial for paper‐based materials to be used in many applications. Based on this, the paper surface was chemically modified with castor oil‐based resin (CO‐590) monomer prepared by coupling agent and castor oil (CO). The results indicated that the modified paper with the contact angle (CA) of 114° had excellent waterproof performance and had a reduction by 40.3% in water vapor transmission rate (WVTR), but also its mechanical increased to 26.9 MPa and the decomposition temperature to 410.5°C. In addition, the coating on its surface could be removed in an alkaline solution and had a possibility to recycle blank paper in the future for manufacturing sustainable production. This work not only provides a method for preparing modified packaging paper, but also expands the application fields of materials. [ABSTRACT FROM AUTHOR]

Abstract: Various parameters that may affect the efficiency of tri- and di-functional aminoalkylalkoxysilanes (AAAS) copolymer treatments to deacidify and mechanically strengthen aged complex papers (lignocellulosic pulp, additives) were studied. Three model papers were first hydrothermally aged (90 °C—50% RH) in order to achieve physicochemical characteristics similar to those of a naturally aged newsprint, and were then treated with AAAS copolymers. The chemical composition of the treatments varied from 50 to 5 wt% of tri-functional monomer APTES, the latter acting as cross-linker in the copolymer network. The respective ratio of tri- and di-functional monomers in the mixture was shown to greatly influence the mechanical properties of the treated papers in the case of APTES/DIAMINO but less so in the case of APTES/AMDES. If APTES/DIAMINO (50/50 wt%) did not strengthen the degraded papers, a higher proportion of DIAMINO (95 wt%) and lower proportion of APTES (5 wt%) led to improving the tensile strength and, more importantly for the function properties of paper, significantly enhancing the folding endurance. The treatment efficiency decreased at higher state of deterioration of the papers and in the presence of alum-rosin sizing. Lastly, the treatments developed for the artificially aged model papers were applied to the degraded newsprint paper specimen and successfully enhanced its mechanical properties.Graphical abstract: [ABSTRACT FROM AUTHOR]

Hydrophobic coatings are of utmost importance for many applications of paper-based materials. However, to date, most coating methods demand vast amounts of chemicals and solvents. Frequently, fossil-based coating materials are being used and multiple derivatization reactions are often required to obtain desired performances. In this work, we present a solvent-free paper-coating process, where olive oil as the main biogenic component is being used to obtain a hydrophobic barrier on paper. UV-induced thiol-ene photocrosslinking of olive oil was pursued in a solvent-free state at a wavelength of 254 nm without addition of photoinitiator. Optimum reaction conditions were determined in advance using oleic acid as a model compound. Paper coatings based on olive oil crosslinked by thiol-ene reaction reach water contact angles of up to 120°. By means of Fourier transform infrared spectroscopy and differential scanning calorimetry, a successful reaction and the formation of a polymer network within the coating can be proven. These results show that click-chemistry strategies can be used to achieve hydrophobic polymeric paper coatings while keeping the amount of non-biobased chemicals and reaction steps at a minimum. [ABSTRACT FROM AUTHOR]

• Nacre-like FG/Al energetic paper was designed and prepared. • A significantly enhanced energy and pressure output are obtained. • FG/Al energetic papers shown self-propagate combustion reaction at micro-scale. • The chemical reaction mechanism was distinctly elucidated. • FG/Al energetic paper displayed high flexibility and strain. Developing functional devices requires energetic materials with comprehensive performance including high energy density, excellent chemical reactivity and mechanical properties. Herein, an effective strategy inspired by nacre-like architecture was employed to construct new fluorographene (FG)/nano-aluminum (Al) energetic paper through a vacuum filtration induced self-assembly process. FG/Al energetic paper showed ultrahigh reactivity and high flexibility owing to combined effect of the nacre-like architecture and interfacial interaction. FG/Al energetic paper exhibited significantly enhanced energy output (3257.7 J/g) and self-propagate combustion reaction with high pressure output at micro-scale. Chemical reaction mechanism was distinctly elucidated based on reactive molecular dynamics simulations and the combustion products of FG/Al energetic paper. More interestingly, FG/Al energetic paper displayed high flexibility and strain (5.39%) reported for the first time. The bio-inspired route provides a promising approach to design advanced energetic materials for applications in transportation, aerospace, and military industries. [ABSTRACT FROM AUTHOR]

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

Efficient and reliable methods for the generation of bioactive papers are of growing interest in relation to point‐of‐care testing devices that do not require extensive analytical equipment. Herein, we report the immobilization of functional proteins on paper fibers using a modular chemoenzymatic approach. The synthetic strategy relies on a combination of highly efficient spatially controllable photo‐triggered cycloaddition followed by site‐specific sortase A‐catalyzed transamidation. This site‐directed and regiospecific method has allowed unidirectional and covalent immobilization of several proteins displaying different functional properties, with ramifications for application in paper‐based diagnostics. Protein‐functionalized paper: A modular approach to covalent protein immobilization on paper fibers is reported, which relies on a set of highly efficient pericyclic reactions in combination with site‐specific enzymatic coupling. Following initial derivatization of a cellulosic surface (see figure), light‐triggered covalent anchoring of an enzyme recognition site ensures enzyme‐promoted ligation of desired proteins with preservation of their function. [ABSTRACT FROM AUTHOR]

The power transformer is an important part of the power grid. The aging of oil-paper insulation is affected by many factors such as temperature and moisture. In order to accurately evaluate the service life of transformer and ensure the stable operation in power system, a method for predicting the lifetime of oil-immersed pressboard under different temperatures and moisture content was proposed. This method is mainly realized by the chemical reaction kinetic equations and transformation factor. Firstly, the effect of temperature and moisture content on the frequency dielectric response of oil-paper insulation was studied by frequency domain dielectric spectroscopy method. The results show that the dielectric loss of oil-immersed pressboard increases with the increase of moisture content and temperature. The activation energy of oil-immersed pressboard also increases exponentially with the increase of moisture content. Then, we analyzed the trend of polymerization degree of insulation pressboard in aging process and calculated the insulation life and the remain lifetime by combining the cellulose degradation kinetic models and translation factor. When the moisture content of the oil-immersed at 70 °C, the life expectancy of oil-paper insulation is about 19.26 years. [ABSTRACT FROM AUTHOR]

Copyright of Restaurator is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pulp and paper industry has generated a higher contamination burden of the final mill wastewater which must be further treated to comply with the standards imposed by the legislation requirement. In this study, the removal efficiencies for chemical oxygen demand (COD) and color from pulp and paper wastewater using sequencing batch reactor (SBR) in combination with advanced oxidation processes (AOPs) at a bench scale were investigated. Response surface methodology (RSM) based on a three-variable-three-level central composite design (CCD) was employed to optimize the SBR process. At the optimal conditions of initial COD of 1000 mg/L, MLSS of 3000 mg/L and cycle time of 24 h, 74.8% COD, 58.3% of color removal and 80 mL/g of SVI were obtained in the pretreatment stage. The use of Fenton oxidation as post-treatment enhanced COD reduction and color removal. A percentage of 92.1% COD reduction and 90.3% of color removal was achieved in dosages of 3 mM Fe2+ and 9 mM H2O2 at pH of 3.0 for a reaction time of 30 min, while a total of 98% reduction of COD and 94% removal of color for the combined treatment was achieved. [ABSTRACT FROM AUTHOR]

A distance-based paper analytical device (dPAD) for loop mediated isothermal amplification (LAMP) detection based on distance measurement was proposed. This approach relied on visual detection by the length of colour developed on the dPAD with reference to semi-quantitative determination of the initial amount of genomic DNA. In this communication, E. coli DNA was chosen as a template DNA for LAMP reaction. In accordance with the principle, the dPAD was immobilized by polyethylenimine (PEI), which is a strong cationic polymer, in the hydrophilic channel of the paper device. Hydroxynaphthol blue (HNB), a colourimetric indicator for monitoring the change of magnesium ion concentration in the LAMP reaction, was used to react with the immobilized PEI. The positive charges of PEI react with the negative charges of free HNB in the LAMP reaction, producing a blue colour deposit on the paper device. Consequently, the apparently visual distance appeared within 5 min and length of distance correlated to the amount of DNA in the sample. The distance-based PAD for the visual detection of the LAMP reaction could quantify the initial concentration of genomic DNA as low as 4.14 × 10 3 copies µL −1 . This distance-based visual semi-quantitative platform is suitable for choice of LAMP detection method, particular in resource-limited settings because of the advantages of low cost, simple fabrication and operation, disposability and portable detection of the dPAD device. [ABSTRACT FROM AUTHOR]

The high cost of regular diagnostic kits severely impeded its uses for routine clinical assay and fieldworks. A cost-effective chromatography paper is chemically modified with Ag nanostructures using the simple electroless silver deposition, producing a scalable and disposable substrate for surface-enhanced Raman spectroscopy, as well as a large scale of catalytic active sites over many chemical reactions. Synergetic measurement including surface-enhanced Raman spectroscopy and laser desorption ionization-mass spectrometry is performed on Ag decorated filter paper using a thiol containing compound as indicator, allowing for the acquisition of spatially correlated spectroscopy in the tandem mode. In addition, hydrophilic porous cellulose network that contains a certain amount of liquid naturally served as a chemical reactor for molecular transport and reaction. Positive results from catalytic reaction on metallized paper convincingly demonstrated that total microanalysis system on paper (μ-TASoP), as a compelling alternative would find a wide breadth of applications in developing disposable medical devices and customary laboratory assays. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Voltammetric determination of morin on carbon fiber paper (CFP) electrode modified by electropolymerization of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) in phosphate buffer solution (PB, pH 9.0) have been studied. This modified electrode showed strong electrocatalytic activity toward the oxidation of morin, a flavonoid at physiological pH (PB, pH 7.0). Morin gave a sensitive anodic peak at 0.245 V (vs. SCE). The parameters influencing the anodic peak of morin such as effect of pH, effect of scan rate and concentration have been optimized. The electrochemical process was found to be irreversible and adsorption-controlled. Under the optimum conditions, the anodic peak current was linear to concentration of morin in the range of 2.5 × 10-10-2.75 × 10-9 M and detection limit was found to be 8.3 × 10-11 M. The practical application of the modified electrode was successfully demonstrated for the determination of morin in mulberry leaves. [ABSTRACT FROM AUTHOR]

Abstract The deposition of chemical reagent inks on paper is a crucial step in the development and fabrication of microfluidic paper-based analytical devices (μPADs). A pen-plotting approach, delivering chemical ink deposition using technical pens filled with reagents and inserted into a desktop electronic plotter, is shown herein to be a versatile, low-cost, simple, rapid, reproducible, and high-throughput solution. The volume of the deposited ink was quantified gravimetrically, confirming that nanoliter volumes of reagents can be deposited reproducibly (e.g. 7.55 ± 0.37 nL/mm for a plotting speed of 10 cm/s) in detection zones of μPADs, typically spatially defined using wax printing. This approach was further investigated with regard to deposition of reagents in different geometrical forms (circular and linear), so demonstrating its applicability for preparation of μPADs with flexible design and application. By adjusting the plotting speed for linear deposition, lines with a relatively large range of widths (≈628–1192 μm) were created. Circular deposition was also demonstrated via delivery of reagents within wax printed circular fluidic barriers of a range of diameters (inner diameter = 1.5–7 mm). These capabilities were practically demonstrated via the fabrication of μPADs, based upon differing detection principles for determination of aluminum in natural waters using Morin as the fluorescent reagent. Traditional μPADs based on digital image colorimetry (DIC) were produced using circular deposition, whilst distance-based μPADs exploited linear deposition. Both types of μPADs developed using this method showed excellent precision for determination of trace concentrations of aluminium (average RSDs = 3.38% and 6.45%, and LODs = 0.5 ng (0.25 ppm) and 2 ng (0.5 ppm), for traditional and distance-based detection, respectively). Graphical abstract Image 1 Highlights • A pen-plotting technique is characterized for chemical ink deposition on μPADs. • A gravimetric approach is introduced to measure the deposition volume. • Deposition is studied for different geometrical forms (circular and linear). • The effect of plotting parameters on deposition is investigated. • The approach is demonstrated by a fluorescence-based determination of Al in waters. [ABSTRACT FROM AUTHOR]

It is important to monitor the water concentration in the insulation of aging power transformers, because over time the insulation becomes wet, due to water ingress from the atmosphere and water formed in chemical reactions involving oxygen. If the water concentration is sufficiently high, the insulation will age prematurely [1] and the transformer may fail if overloaded [2]. In a previous article [3] we reported on the measurement of water concentration in the insulation paper of a power transformer that had been in service for only seven years. The waterconcentration data obtained using on-line water-activity probes were compared with corresponding data obtained from dielectric response measurements. In that work cellulose adsorption isotherms were used to process the water-activity-probe data. However, according to [4] and [5], inaccuracies in the waterconcentration estimates may result from the use of adsorption isotherms. According to [6], these inaccuracies may exceed 200%. The probable main causes are the transformer insulation materials not reaching thermal equilibrium, the water concentration within the insulation not being uniform, and variability in the properties of the insulating materials. [ABSTRACT FROM AUTHOR]

Carbon paper (CP) used for proton exchange membrane fuel cells (PEMFCs) are improved using carboxyl-terminated butadiene-acrylonitrile (CTBN)-modified phenolic resin (PF) for impregnation of CP preform. The effect of CTBN ratio on the properties of CP, which is fabricated by the processes of impregnation, molding and heat treatment, is investigated. The results show that compared with the CP without CTBN addition, the CTBN-modified CP exhibits significantly improved overall properties. With the increase of CTBN ratio in the mixture, porosity and permeability of the modified CP increase because of the low carbon yield of CTBN after heat treatment. Mechanical strength and conductivity also increase because of the chemical reactions between the CTBN and resin that lead to robust interfacial bonding in the CP product. However, excessive CTBN addition causes decreased tensile and bending strength of the CP. Single cell tests show that the increased conductivity of the CP enhances the polarization performance in the Ohm polarization region, while the CTBN-induced nearly spherical micro/macro-pores in the CP matrix improve the performance in the concentration polarization region. At an optimum CTBN ratio of 50 wt%, the membrane electrode assemble with the modified CP exhibits a current density of 1606.5 mA cm −2 at 0.608 V. [ABSTRACT FROM AUTHOR]

This article describes a new, simplified approach for performing quantitative colorimetric assays on paper-based analytical devices that uses calibrant-loaded paper devices to perform external calibration and standard addition calibration using one calibration point. Calibrant-loaded devices consist of sensing areas pre-loaded with a colored product which is produced from the reaction of a standard solution of the analyte with the appropriate colorimetric reagents. When the sample is added into the calibrant-loaded sensing zone the analytical signal (i.e. color intensity) increases proportionally to the concentration of the analyte in the tested sample. The total measured signal corresponds to the sum of the concentration of the analyte in the sample and the standard solution pre-stored in the device and is used to calculate the concentration of the analyte in the sample based on the principles of linear calibration. The applicability of this approach was benchmarked in three colorimetric assays (i.e., for the determination of iron, nickel, and amino acids) that use different reaction chemistries. This work demonstrates a simplified calibration-free approach for assays performed on paper-based analytical devices that requires minimum experimental and computational effort, it can be used for either external or standard addition calibration and can be used to identify and eliminate the presence of interferences in a sample. Image 1 • A new and simplified approach for quantitative assays on paper devices is described. • Single-point calibration and standard addition on paper devices is demonstrated. • The method can be used to identify the presence of interferences in the sample. • The method produces rapid results with minimum user effort and technical resources. [ABSTRACT FROM AUTHOR]

The rapid on-site detection of organophosphate compounds such as nerve agents and pesticides is essential due to their lethal effect, which irreversibly inhibits the activity of acetylcholinesterase (AChE). In this study, we demonstrate a foldable paper-based analytical device (PAD) that is capable of detecting an AChE inhibitor in a semiquantitative manner. An angle-based readout of the yellow area in the ring-type paper channel was used for the semiquantitative analysis with the naked eye. The color of the paper channel was changed to yellow as a result of oxidized cerium oxide nanoparticles by hydrogen peroxide produced from the enzymatic reactions. All reagents required for enzyme reactions were preadsorbed on the pop-up card shaped PAD to minimize the manual steps for dealing with multiple reagents for sequential enzyme reactions. As a proof of concept, we were able to semiquantitatively analyze a nerve agent simulant called dimethyl methylphosphonate (DMMP), one of the AChE inhibitors, by simply reading the angle of the yellow area in the paper channel. The foldable PAD proposed here would serve as a valuable tool that allows unskilled people to semiquantitatively detect AChE inhibitors in the field, including nerve agents and organophosphate pesticides. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is an attractive technology to address problems associated with moisturerich pulp and paper sludge generated at South African mills and wastewater treatment plants. In this study, sludge generated from the repulping process, recycling paper process, and primary clarifier wastewater treatment were selected to investigate the potential of HTC to upgrade the feedstock into solid fuel. Experiments were performed in a batch reactor autoclave at different operating temperatures (200 °C, 220 °C and 240 °C), residence time of 3 h, and wet biomass to deionized water ratio of 1:9. Data on the physicochemical characteristics and calorific values of the solid yield, as well as carbon mass distribution, were reported. Results revealed that higher temperatures resulted in hydrochar with higher calorific values from 15.26 to 22.57 MJ/kg, 15.33 to 20.32 for repulping paper sludge and recycling paper sludge, respectively, but lower calorific values (from 9.79 MJ/kg to 7.02 MJ/kg) for sludge from primary clarifier process. The proportions of fixed carbon for hydrochars obtained at 245 °C were 5-7 times greater than the raw samples, but solid mass yield decreased with an increase in reaction temperatures for all feedstocks. Analysis of the carbon mass balance revealed that, for all HTC treatments, the majority of the carbon fraction was retained in the hydrochar. HTC was proven to be an efficient technology for upgrading sludge generated at pulp and paper mills in South Africa into hydrochar with enhanced properties with a variety of applications including solid fuel, energy storage, soil amendment, adsorbent and catalyst. [ABSTRACT FROM AUTHOR]

Activation energy is popularly used for the estimation of remaining life of transformer insulation. It is defined as the average rate of all reactions that happen with cellulose. Existing literature shows that the activation energy of oil–paper insulation can be obtained from polarization depolarization current (PDC) and return voltage measurement (RVM) data that are measured at a specific temperature. It is practically difficult to ensure the same measurement temperature for both PDC and RVM data. On the other hand, PDC data and its analysis get influenced by de-trapping current. This de-trapping current is generated by ionic charge carriers that get freed from trap sites during PDC measurement process. Formation of these trap sites is related to physical, chemical reactions that happen at oil–paper interface. This paper proposes a methodology which uses de-trapped charge, dislodged from deep and shallow traps, to assess insulation condition and for the prediction of activation energy. Thus, eliminating the need of RVM data. The proposed method is tested using data collected from various real-life in-service transformers. [ABSTRACT FROM AUTHOR]

Abstract Background Food contact materials (FCM) may contain non-intentionally added substances (NIAS) as a result of reaction by-products, oligomers, degradation processes, chemical reactions between packaging materials and foodstuff, or as impurities from the raw materials used for their production. Scope and approach In this review, current approaches for the detection and identification of NIAS from paper and board FCM are presented. Reviewed are the definition of NIAS, approaches for NIAS identification and quantification, the comprehensive analysis of NIAS and the role of in silico tools and bioassays. Key Findings and Conclusions NIAS in paper and board are mostly components from printing inks, adhesives, sizing agents and surface coatings. Recycled paper contains overall more NIAS than fresh paper. Targeted analysis is generally performed for predicted NIAS, whereas an untargeted, or full-scan screening method is applied to detect and identify unpredicted NIAS. Sample preparation and contact conditions fall in two categories; migration and extraction. Migration studies are performed with food simulants while extraction studies are Soxhlet or ultrasound assisted solvent extraction. In untargeted analysis in silico tools are gaining importance in the identification of NIAS. Bioassays are used to determine the bioactivity of extracts or fractions in order to assess the potential toxicity of NIAS present in the mixture. A combination of bioassays and chemical analysis is used to direct the identification of unknown bioactive NIAS in complex mixtures like those from paper and board FCM. However, future research is required into the selection of bioassays since these should not only be sensitive enough for detecting all compounds of concern but should also have a relevance with human health. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray (PS) has been developed as a method of choice for point‐of‐care analysis in many real cases, where its applications can be further expanded with delicate high‐throughput design. To achieve this goal, we developed a new PS regime, with the assembly of an induced high voltage into the ion source. Compared with regular DC high voltage, the newly developed setup is capable of high‐throughput, simple configuration and rapid switching between individual papers without complicated electric/mechanic design. Methods: A device of high‐throughput induced PS (IPS) was designed by using a two‐dimensional (2D) rotating platform equipped with a circular glass plate. The paper substrate was placed on the circular glass plate and separated from the electrode. The method avoids physical contact between the electrode and the sample. Charged droplets were generated at the paper tip once an induced high voltage was applied to a wet paper. Results: A relatively rapid analytical speed of 2.6 s per sample was achieved via IPS‐MS. Rapid quantification of amitriptyline (AMT) in complicated matrices was obtained within 1 min using an isotope internal standard method. Limits of detection for AMt in urine, FBS and blood were calculated to be 1.04, 0.84 and 1.33 ng/mL, respectively. In addition, high‐throughput IPS‐MS can be used for chemical reaction monitoring. Conclusions: We have demonstrated the versatility of high‐throughput IPS‐MS in ambient ionization, which successfully simplified the experimental installation and facilitated the experimental operation. Therefore, we believe that high‐throughput IPS‐MS analysis will be widely used for discovering drugs and screening reactions, and the present design has the potential for applications in paper chip‐MS analysis. [ABSTRACT FROM AUTHOR]

A simple, fast, low-cost, portable, and eco-friendly method using a spot test on a paper platform, together with diffuse reflectance spectroscopy, was developed and validated for the quantification of aluminum hydrochloride, a potential neurotoxic agent, in antiperspirant samples. The determination of aluminum hydrochloride was performed at a wavelength of 615 nm, by measuring consumption of the purple colorimetric reagent Alizarin S, due to reaction with aluminum. The linear range was from 10.0 to 125.0 mg L −1 and could be described by the equation: A R  = 0.4479 − 0.002543 C Al (R = 0.999). The limits of detection (LOD) and quantification (LOQ) were 3.06 and 10.2 mg L −1 , respectively. The method was specific, accurate, and repeatable, with relative standard deviation (RSD) <5.0%. The recovery was between 92.2 and 103.4%. The method was successfully used for the determination of aluminum hydrochloride in commercial antiperspirant samples, revealing concentrations below the maximum permitted by current legislation. [ABSTRACT FROM AUTHOR]

Due to the scarcity of natural resources, the option for the recovery of industrial waste for new processes has increased over the last years. However, seeking natural raw materials, some industrials do not perform treatment or separation of some of its components from waste to be reused. This research focuses on the characterization and purification of waste from the industrial pulping of white paper shavings, obtaining kaolin and CaCl 2 . The waste was subjected to heat treatment at 400 °C to burn the cellulose. To separate the CaCO 3 of kaolin, a hydrochloric acid (HCl) solution was used to purify the materials, converting CaCO 3 into CaCl 2 and water in a chemical reaction. To find the best HCl ratios, tests were carried out at three different concentrations: 1.5, 1.8, 2.1 M. Residual water was evaporated to recover the CaCl 2 , and the resulting kaolin from pulp was oven-dried and turned into metakaolin. The analysis performed for the characterization of the materials were: X-ray Fluorescence (XRF) before and after treatment of the material; X-ray Diffraction (XRD); Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA). Scanning Electron Microscope (SEM) was used on the surface structure, morphology and shape studies. [ABSTRACT FROM AUTHOR]

Pyocyanin is a toxin produced by Pseudomonas aeruginosa. Here we describe a novel paper-based electrochemical sensor for pyocyanin detection, manufactured with a simple and inexpensive approach based on electrode printing on paper. The resulting sensors constitute an effective electrochemical method to quantify pyocyanin in bacterial cultures without the conventional time consuming pretreatment of the samples. The electrochemical properties of the paper-based sensors were evaluated by ferri/ferrocyanide as a redox mediator, and showed reliable sensing performance. The paper-based sensors readily allow for the determination of pyocyanin in bacterial cultures with high reproducibility, achieving a limit of detection of 95 nM and a sensitivity of 4.30 μA/μM in standard culture media. Compared to the similar commercial ceramic based sensors, it is a 2.3-fold enhanced performance. The simple in-house fabrication of sensors for pyocyanin quantification allows researchers to understand in vitro adaptation of P. aeruginosa infections via rapid screenings of bacterial cultures that otherwise are expensive and time-consuming. [ABSTRACT FROM AUTHOR]

Excess tosyl chloride used in the tosylation of alcohols is quickly and easily removed by reacting it with cellulosic materials, e.g., filter paper, and filtering. [ABSTRACT FROM AUTHOR]

The article discusses a study on the synthesis of iron fatty acid particles for use in the preparation of composite coating solutions. Topics include the synthesis of the iron fatty acid derivative through the reaction between iron chloride hexahydrate and fatty acid, the fabrication of a superhydrophobic filter paper through spray coating and the potential of the particles to induce self-cleaning properties.

A spray method is proposed to improve the catalytic properties of ceramic papers to be used as catalytic filters for removing diesel soot particles. Small particles of Ce and Co oxides, acting as active centers for the combustion of the soot retained by the filter, are efficiently and homogeneously deposited. On the contrary, the application of the conventional drip method results in bigger particles mainly agglomerated at the crossings between the fibers of the ceramic paper. As a result, catalytic papers prepared by the spray method exhibit much higher performance with soot combustion temperatures decreased by ~ 30 °C. [ABSTRACT FROM AUTHOR]

A paper-structured catalyst (PSC) for biogas reforming was prepared with the aim of improving coking tolerance. During the paper-making process using inorganic fibers, Ni-loaded (Ce,Zr)O 2–δ particles were synthesized via co-precipitation and subsequent chemical reduction (on-paper synthesis). The effects of the CeO 2 /ZrO 2 weight ratio during preparation and the Ni loading amount on the catalytic activity for dry reforming of CH 4 were investigated at 750 °C. A Ni loading of 6 wt% with CeO 2 /ZrO 2 ≥ 1 led to stable CH 4 conversion of 85% without coking under a gas hourly space velocity of 3800 h −1 . The oxygen storage capacity of the (Ce,Zr)O 2–δ particles dispersed in the inorganic fiber network may contribute to the oxidation of carbonaceous species deposited on the catalyst surface. [ABSTRACT FROM AUTHOR]

High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2-DHB). Enzyme was added at constant loading (24 kg ton-1), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2-DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties. [ABSTRACT FROM AUTHOR]

We present an automatically generated dataset of 15,755 records that were extracted from 47,357 papers. These records contain water-splitting activity in the presence of certain photocatalysts, along with additional information about the chemical reaction conditions under which this activity was recorded. These conditions include any co-catalysts and additives that were present during water splitting, the length of time for which the photocatalytic experiment was conducted, and the type of light source used, including its wavelength. Despite the text extraction of such a wide range of chemical reaction attributes, the dataset afforded good precision (71.2%) and recall (36.3%). These figures-of-merit were calculated based on a random sample of open-access papers from the corpus. Mining such a complex set of attributes required the development of novel techniques in knowledge extraction and interdependency resolution, leveraging inter- and intra-sentence relations, which are also described in this paper. We present a new version (version 2.2) of the chemistry-aware text-mining toolkit ChemDataExtractor, in which these new techniques are included. [ABSTRACT FROM AUTHOR]

Abstract: A potentially universal approach is presented for enzyme attachment to cellulose that significantly enhances enzyme stability while retaining high activity, and involves no chemical functionalization of cellulose. Bovine serum albumin (BSA) was interlocked in cellulose to form a protein‐friendly surface (named BSA‐Paper), while also providing COOH and NH2 groups for subsequent attachment of enzymes. The desired enzyme is then mixed with additional BSA and interlocked on BSA‐Paper. The second BSA layer dilutes and crosslinks the enzyme for improved stability. Laccase was tested as a model enzyme for interlocking on BSA‐Paper, and was found to retain over 100 % activity and was 240 times more stable at 25 °C (half life=180 d) than laccase. This new approach was also tested with a few other enzymes with encouraging results, thus providing a potentially universal method for stabilization of enzymes on cellulose with retention of high activities. [ABSTRACT FROM AUTHOR]

Characterization of porewater chemistry in low-permeability, clay-rich rocks provides insights into solute transport mechanisms and the origin and residence time of porewater. Extraction of porewater for chemical quantification is challenging, and several methods have been applied including squeezing, advective displacement, crush and leach, and a relatively new technique that extracts porewater by absorption into a cellulosic paper by capillary action. Here we compare porewater Cl− and Br− mass ratios from samples using the paper-absorption and crush-and-leach techniques. Samples were obtained from Upper Ordovician shales in the Michigan Basin in Ontario, the Opalinus Clay at the Mont Terri Rock Laboratory in Switzerland, and the Upper Ordovician Lorraine Group shale in southern Quebec. The data display consistent and reproducible differences among methods for Cl− and Br− mass ratios, with the paper-absorption method producing systematically lower Cl− : Br− ratios. The observed differences in Cl− : Br− ratios are attributed primarily to anion exclusion effects which are stronger for Br− than for Cl−, resulting in higher Br− concentrations in the largest pores that are preferentially sampled by the paper-absorption technique. In addition, calculations suggest that Cl− is more effective than Br− in forming ion pairs and clusters with neutral or positive charge which can enter the diffuse double layer. This causes a further decrease in the Cl− : Br− ratios for the mobile water. One important message from this work is that different extraction methods should not be expected to converge on a unique porewater Cl− : Br− ratio because each method reflects different proportions of the interlayer, diffuse double layer, and mobile fractions of porewater. [ABSTRACT FROM AUTHOR]

Owing to the multiple potential health risks caused by exposure to BPA and the strengthened regulation of BPA-containing thermal papers, much concern has been raised recently regarding a BPA-type color developer in thermal papers. However, few efforts have so far been focused on the development of safer alternative materials to BPA. In this study, we examined the use of polymeric materials as a safer replacement for BPA in thermal papers. For this objective, a series of phenolic polymers, phenol-formaldehyde novolac and resole (PF-N and PF-R) and BPA-formaldehyde novolac and resole (BPAF-N and BPAF-R), were prepared. Among these polymers, a BPAF-N-type polymer was determined to be the most appropriate candidate for a developer material in thermal papers. Through printing tests of the prepared thermal papers, it was found that BPAF-N_8 polymer has a high static sensitivity and dark contrast of thermal papers similar to those of BPA, whereas the BPAF-N_16 and BPAF-N_30 polymers have lower static sensitivities than BPFA-N_8 and BPA. [ABSTRACT FROM AUTHOR]

Recent studies suggest that reactions in aqueous microcompartments can occur at significantly different rates than those in the bulk. Most studies have used electrospray to generate a polydisperse source o f highly charged microdroplets, leading to multiple confounding factors potentially influencing reaction rates (e.g., evaporation, charge, and size). Thus, the underlying mechanism for the observed enhancement remains unclear. We present a new type of electrodynamic balance— the branched quadrupole trap (BQT)—which can be used to study reactions in microdroplets in a controlled environment. The BQT allows for condensed phase chemical reactions to be initiated by colliding droplets with different reactants and levitating the merged droplet indefinitely. The performance of the BQT is characterized in several ways. Sub-millisecond mixing times as fast as ~400 μs are measured for low velocity (~0.1 m /s) collisions of droplets with <40 μm diameters. The reaction of o-phthalaldehyde (OPA) with alanine in the presence of dithiolthreitol is measured using both fluorescence spectroscopy and single droplet paper spray mass spectrometry. The bimolecular rate constant for reaction of alanine with OPA is found to be 84 ± 10 and 67 ± 6 M-1 s-1 in a 30 μm radius droplet and bulk solution, respectively, which demonstrates that bimolecular reaction rate coefficients can be quantified using merged microdroplets and that merged droplets can be used to study rate enhancements due to compartmentalization. Products of the reaction of OPA with alanine are detected in single droplets using paper spray mass spectrometry. We demonstrate that single droplets with <100 pg of analyte can easily be studied using single droplet mass spectrometry. [ABSTRACT FROM AUTHOR]

The present work reports on the development of a pressure-affected based headspace (HS) analytical technique for the determination of calcium carbonate content in paper samples. By the acidification, the carbonate in the sample was converted to CO 2 and released into the headspace of a closed vial and then measured by gas chromatography (GC). When the amount of carbonate in the sample is significant, the pressure created by the CO 2 affects the accuracy of the method. However, the pressure also causes a change in the O 2 signal in the HS-GC measurement, which is a change that can be used as an indirect measure of the carbonate in the sample. The results show that the present method has a good precision (the relative standard deviation < 2.32%), and good accuracy (the relative differences compared to a reference method was < 5.76%). Coupled with the fact that the method is simple, rapid, and accurate, it is suitable for a variety of applications that call for the analysis of high carbonate content in paper samples. [ABSTRACT FROM AUTHOR]

The oil-impregnated paper, which is the major section in converter transformer, plays a considerable role in the reliability and safety of power grid. However, the insulation degradation will be accelerated by the accumulation of charges that are on the surface of oil-impregnated paper. Therefore, the operating overvoltage occurs and irremediable damage will appear. Direct fluorination is an effective method of modifying the chemical components of polymer matrix so as to have effects on the surface characteristic of the insulating material without reforming the bulk properties. In this research, for studying effects of fluorination on charge behavior on the surface of oil-impregnated paper under the application of DC and impulse voltage, the F2/N2 compound, which the volume fraction for the F2 gas occupied 10 % and the pressure was 0.05 MPa in a reaction kettle for 5, 30 and 60 min respectively, was applied. Meanwhile, the chemical bond groups and the surface morphology of the fluorinated specimen were tested. Besides, the DC voltage amplitude was 4 kV and the applied time was 4 min. The impulse frequency was 500 Hz and the impulse voltage amplitude was 1, 2, 3 and 4 kV, respectively. The charge properties under various situations were investigated. From the research under the application of different fluorination time, impulse voltage amplitudes and polarities, conclusions can be drawn that, fluorination has significant effects on the chemical structure properties and surface characteristic of oil-impregnated paper. Furthermore, the initial potential can be reduced and the decay process of surface charge can be accelerated with different fluorination time increasing from 0 to 30 min. Nevertheless, the tendency is the opposite when the fluorination time continuously extends from 30 to 60 min. The trap distribution also exhibits alternation through the fluorination. [ABSTRACT FROM PUBLISHER]

Agro-wastes valorization focusses on production of high value-added products, such as cellulose nanofibers (CNF), and contributes to reduce the environmental impact of these residues. CNF have been used successfully as papermaking additives and some previsions maintain that this sector will become the most important, demanding CNF at a reasonable cost. Furthermore, the optimization of the production process of CNF from agricultural residues would contribute to the goals of a circular economy, the development of rural areas and the costs reduction by producing CNF of the minimum quality fit-for-use in recycled paper. In this study, CNF was produced from two agricultural residues; corn (C-CNF) and rape (R-CNF) stalk pulps, pretreated with bleaching, refining and TEMPO-mediated oxidation. Coagulant and cationic polyacrylamide (dual system) and chitosan were the retention systems. Results show the difficulty of predicting the effect of CNF based on their properties, as fibrillation degree or anionic charge, on the improvement of mechanical properties of recycled paper. That is proved by the low differences in tensile index (TI) improvement (∼15% by adding 0.5% C-CNF combined with dual system), obtained with CNF with very different properties. The expensive TEMPO pretreatment could be avoid by applying bleaching pretreatment to the corn pulp, increasing the TI up to 15% without affecting drainage and decoupling the simultaneous deterioration of drainage with TI improvement (drainage time decreased nearly 50% and 20% adding bleached R-CNF and C-CNF, respectively, combined with chitosan). Similar improvements on TI can be achieved by replacing the dual retention system by chitosan without addition of CNF, but the combination of CNF and chitosan allows achieving the highest TI values. [ABSTRACT FROM AUTHOR]

• Chemical principles are used to direct the preservation and conservation of paper cultural relics. • The mechanisms of acidic, alkaline and oxidative degradation of cellulose, hemicellulose and lignin in paper are summarized. • The intrinsic and extrinsic factors affecting the degradation process of paper are addressed. • The advantages and disadvantages of remedial and preventive conservation methods for paper relics are discussed. Paper cultural relics, with the great historic and artistic value, experience aging and degradation during their long-term preservation. The degradation of paper involves various chemical reactions with complicated mechanisms due to the multiple components of paper itself and the complex factors that promote paper aging process. Therefore, it is of great importance to deeply understand the chemical essence and scientific principle of paper degradation, so as to propose the effective conservation methods for paper relics. This review summarized the chemical mechanisms of acidic, alkaline and oxidative degradation of cellulose, hemicellulose and lignin in paper, and discussed the intrinsic and extrinsic factors that affect paper degradation systematically. Moreover, the interaction among the three types of degradation routes was analyzed for the first time, and the evolution of kinetic models for paper degradation was introduced to evaluate the durability and expected lifetime of paper. On this basis, the advantages and disadvantages of remedial and preventive conservation methods for paper relics are summarized, and the fundamental scientific principles was prospected to guide the further development of paper conservation methods. [ABSTRACT FROM AUTHOR]

We proved that ice crystallized from water molecules within as-synthesized graphene oxide (GO) can be used as a spacer among individual GO sheets to form an expanded GO aerogel with a three-dimensional porous network structure. This designed specific structure can be retained during further processes to form graphene paper. Due to the fact that the as-fabricated graphene paper contains carbon defects and space in its infrastructure, this creates more electroactive surfaces and interfaces to significantly increase the Faradaic reaction efficiency. With the introduction of redox-electrolyte K3Fe(CN)6 into a KOH electrolyte, we can obtain a 95-fold increase in the specific capacitance compared with the value obtained in the traditional KOH electrolyte. The ice-crystallization formed graphene paper electrode showed high electroactivity because the specific porous structure can favor the fast transfer of electrolyte ions, such as Fe(CN)63- ions. The presented results prove that ice-crystallization formed GO can serve as a chemically tunable platform for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]