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Publisher Copyright: © 2022, The Author(s). Direct fire, indirect heat, and extinguishing water cause great damage to cultural assets upon a fire disaster in a library or archive. Conservation and restoration of heat-damaged papers are particularly challenging due to the complexity and severity of the damage. Since valuable originals obviously cannot be used for the development of treatment methods and only to a limited extent for the analysis of the damage, it is necessary to produce model paper materials that have a high degree of similarity to fire-damaged papers, which was addressed in the present study. Three different heating methods were tested to produce model papers of different heating levels. Their altered optical, structural, and chemical properties were analyzed and compared with the results of original fire-damaged samples. The study points out pathways to enable the production of comparable sample materials. Heating between hot plates or in an oven produces papers that have properties quite similar to the originals in terms of surface area, paper structure, cellulose integrity, and interactions with water. Stack heating in the oven has proven to be a particularly effective manufacturing method for larger quantities of model papers.

In this work, we present for the first time, a simplified fabrication of a laminated paper-based analytical device (LPAD) with a free-mobile app, Palette Cam, for image analysis. A filter paper is cut in a rectangular shape (9 × 3 cm) and placed between a top laminating sheet with punched holes and a bottom laminating sheet. The holes allow accessibility of liquid on the paper. Thermal lamination is then employed to complete the fabrication of LPAD. Our simplified design reduces a tedious alignment of small pieces of paper to the holes. We demonstrated the LPAD with an analysis of salicylic acid in pharmaceutical products. Each 4 μL of ferric reagent and sample was dispensed on the LPAD. Smartphone was used to capture images. The RGB (red green blue) color intensity from the Palette Cam was converted into a logarithm color ratio. Our LPAD is simplified, cost-effective and able to be a portable device.

The prevalence of diabetes has increased over the past years. Therefore, developing minimally invasive, user-friendly and cost-effective glucose biosensors is necessary especially in low-income and developing countries. Cellulose paper-based analytical devices have attracted the attention of many researchers due to affordability, not requiring trained personnel, and complex equipment. This paper describes a microfluidic paper-based analytical device for the detection of glucose in tear with the naked eye. The paper-based biosensor fabricated by laser CO2, and GOx/HRP enzymatic solution coupled with TMB was utilized as reagents. A sample volume of 10 µl was needed for the biosensor operation and the results were observable within 5 minutes. To evaluate the device performance, color intensity-based and distance-based results were analyzed by ImageJ and Tracker. Distance-based results showed a linear behavior in the range of 0.1–0.6 mM with an R2 = 0.967 and LOD of 0.2 mM. The results could be perceived by the naked eye without any need to further equipment or trained personnel in a relatively short time (3–5 minutes). Moreover, glucose concentration could be obtained non-invasively by tears collected by this µPAD.

Is it really better to print everything, including software models, or is it better to view them on screen? With the ever increasing complexity of software systems, software modeling is integral to software development. Software models facilitate and automate many activities during development, such as code and test case generation. However, a core goal of software modeling is to communicate and collaborate. Software models are presented to team members on many mediums and two of the most common mediums are paper and computer screens. Reading from paper or screen is ostensibly considered to have the same effect on model comprehension. However, the literature on text reading has indicated that the reading experiences can be very different which in turn effects various metrics related to reader performance. This paper reports on an experiment that was conducted to investigate the effect of reading software models on paper in comparison with reading them on a computer screen with respect to cognitive effectiveness. Cognitive effectiveness here refers to the ease by which a model reader can read a model. The experiment used a total of 74 software engineering students as subjects. The experiment results provide strong evidence that displaying diagrams on a screen allows subjects to read them quicker. There is also evidence that indicates that on screen viewing induces fewer reading errors.

Funding Information: Open access funding provided by FCT|FCCN (b-on). This work was financed by national funds from Fundação para a Ciência e a Tecnologia (FCT), I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020, and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication–i3N and by FEDER funds through the COMPETE 2020 Program and National Funds through Portuguese Foundation for Science and Technology under projects POCI-01–0145-FEDER-007688, UID/CTM/50025 and by ERC AdG grant from the project DIGISMART (ERC-AdG-2017, GA 787410). J.C. would like to acknowledge FCT/MCTES for his present research contract with reference CEECIND/00880/2018. R.C. acknowledges funding from i3N-FCT I.P. through the PhD Grant UI/BD/151295/2021. S. S. and T. P. also acknowledge the funding from National Foundation for Science and Technology, through the PhD Grants SFRH/BD/149751/2019 and 2020.08606.BD, respectively. Publisher Copyright: © 2022, The Author(s). Laser-induced graphene (LIG) is as a promising material for flexible microsupercapacitors (MSCs) due to its simple and cost-effective processing. However, LIG-MSC research and production has been centered on non-sustainable polymeric substrates, such as polyimide. In this work, it is presented a cost-effective, reproducible, and robust approach for the preparation of LIG structures via a one-step laser direct writing on chromatography paper. The developed strategy relies on soaking the paper in a 0.1 M sodium tetraborate solution (borax) prior to the laser processing. Borax acts as a fire-retardant agent, thus allowing the laser processing of sensitive substrates that other way would be easily destroyed under the high-energy beam. LIG on paper exhibiting low sheet resistance (30 Ω sq−1) and improved electrode/electrolyte interface was obtained by the proposed method. When used as microsupercapacitor electrodes, this laser-induced graphene resulted in specific capacitances of 4.6 mF cm−2 (0.015 mA cm−2). Furthermore, the devices exhibit excellent cycling stability (> 10,000 cycles at 0.5 mA cm−2) and good mechanical properties. By connecting the devices in series and parallel, it was also possible to control the voltage and energy delivered by the system. Thus, paper-based LIG-MSC can be used as energy storage devices for flexible, low-cost, and portable electronics. Additionally, due to their flexible design and architecture, they can be easily adapted to other circuits and applications with different power requirements. Graphical Abstract: [Figure not available: see fulltext.] publishersversion published

The membraneless-gas separation microfluidic paper-based analytical device (ML-GS μPAD), consisting of donor, spacer, and acceptor layers, was developed to monitor total ammonia in fish pond water. The principle of the analysis involved the addition of sodium hydroxide solution to the sample zone in the donor layer containing ammonia/ammonium, and the produced ammonia gas diffuses through the spacer to the detection zone in the acceptor layer containing red rose extract to produce a color change from pink to blue corresponding to the ammonia/ammonium concentration. Under optimum conditions, the proposed method provided good linearity of ammonia in the range concentration of 0-100 mg L

The existence of pesticide residues in the hydrosphere, biosphere, and anthroposphere can cause acute or chronic diseases and deteriorate the environment. Therefore, efficient detection of pesticide residues is of great significance to prevent food poisoning, control food pollution, and protect human lives by recognizing their distribution and concentration. Herein, a novel smartphone-coupled three-layered paper-based microfluidic chip is proposed as a facile platform to detect the pesticides. The stereoscopic capillary-driven fluid transport is enabled by the three-layered microfluidic chip configuration. The detection mechanism is based on the enzyme inhibition reaction and the chromatic reaction. The detection results are obtained by a smartphone and figured out by colorimetric quantitative analysis. Taking advantages of the above merits, we demonstrate the utilization of this smartphone-coupled three-layered paper-based microfluidic chip for the effective analysis of typical pesticides (profenofo and methomyl). The linear ranges of profenofo and methomyl are 0.27-2.1 μmol L

Research on text comprehension in relation to the reading medium (paper or screen) has mainly involved undergraduate or high school students. To advance current knowledge on the effects of reading medium, this longitudinal study focused on beginner readers, specifically, the role of precursors in first graders’ comprehension of narrative and expository linear texts from reading on paper and computer screen. Working memory and inference skills as cognitive precursors and basic digital skills were measured at the end of preschool (T1); reading text comprehension and word reading, as a control variable, were measured at the end of the first grade (T2). Sixty-three children participated in total. The first graders read four texts, one narrative and one expository, on both paper and computer screen, in a counterbalanced order. Results showed no main effects of the reading medium or text genre, but the interactive effect of these variables was significant. At T2, the children had higher comprehension scores after reading narrative than descriptive texts from paper. In addition, reading from the screen was preferred at post-test, after all texts were presented. As precursors, working memory and inference skills predicted both printed and digital text comprehension. In contrast, basic digital skills predicted only digital text comprehension after controlling for medium, text genre, and word reading.

Point-of-care testing (POCT), as a portable and user-friendly technology, can obtain accurate test results immediately at the sampling point. Nowadays, microfluidic paper-based analysis devices (μPads) have attracted the eye of the public and accelerated the development of POCT. A variety of detection methods are combined with μPads to realize precise, rapid and sensitive POCT. This article mainly introduced the development of electrochemistry and optical detection methods on μPads for POCT and their applications on disease analysis, environmental monitoring and food control in the past 5 years. Finally, the challenges and future development prospects of μPads for POCT were discussed.

Paper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L−1 of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L−1 and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract

This column is intended to address the kinds of knotty problems and dilemmas with which many scholars grapple in studying health professions education. In this article, the authors address the question of why papers may be desk rejected (rejected without going out for formal peer review) and describe simple steps for authors to optimize their work so it gets past the desk reject stage. Submitted/Accepted version

A series of new coloring materials in nanoscale based on 5-(2-aminothiazol-5-yl) thiazol-2-amine and 5-(4-aminophenyl) thiazol-2-amine were synthesized. The nanoscale pigments were prepared using a grinding high˗energy ball-milling technique. X-ray diffraction and transmission electron microscopy were employed to determine the particle size of the nanoscale pigments (40–80 nm). The synthesized pigments in normal and nanoscale were applied in the printing of polyester fabrics. The fastness and colorimetric properties of the printed samples were carefully studied. Additionally, the synthesized pigments were applied as water-based flexographic ink for paper and carton. The hue of the color pigments L*, a*, b*, glossiness, and fastness to light were measured. The comparison of the new heterocyclic benzidine analogs in normal and nanoscale with commercial benzidine pigments demonstrated better results, particularly for the nanoscale pigments.

SummaryInhibitors of the cyclin-dependent kinases 4/6 (CDK4/6i) have been practice-changing and are now considered the standard of care in combination with endocrine therapy for the first- or second-line treatment in advanced hormone-receptor-positive, human epidermal growth factor receptor 2‑negative breast cancer. Recently, CDK4/6i have also emerged as an appealing targeted cancer therapy in early breast cancer, however results of large clinical trials are controversial. This position paper summarizes the evidence, and provides guidance for clinical practice.

Million tons of cellulosic paper have been used for insulating coils in oil-filled electrical power transformers, thereby assuring the electricity supply for our societies. The high working temperatures in transformers constantly degrade paper insulators throughout their service life of up to 40 years. We approached the structural changes in oil-immersed cellulosic paper samples upon thermal stress in a study that compared unbleached softwood Kraft paper used as insulator paper with pure cotton cellulose paper. The model experiments used a thermal treatment in transformer oil at 170 °C for up to 14 days. The samples were characterized by means of 13C CP/MAS NMR spectroscopy, mainly based on deconvolution of the C4 resonance. An automated, fast, and reproducible C4 resonance deconvolution employing the “Peak Analyzer” tool of OriginPro 2020 (OriginLab Corporation, USA) was developed and used to exploit 13C CP/MAS NMR spectroscopy for the characterization of thermally stressed paper samples. Our results show that thermally induced structural changes depend heavily on the composition of paper, that hornification and coalescence of fibrils take place, and that the allomorph composition of cellulose crystallites is altered under the given conditions. Graphical abstract

Water absorption is a key property in several tissue paper materials and can be a differentiating factor in terms of consumer choice. The converting modifications applied in the tissue industry can improved absorbency properties. For this purpose, the main goal of the present work is to study the influence of “deco” and “micro” embossing on water absorption capacity, Klemm capillary rise, and liquid spreading kinetics in tissue papers. An industrial never-dried bleached eucalyptus kraft pulp, a creped industrial base tissue paper, and a disintegrated fibrous suspension obtained from the same industrial paper were used to produce structures with and without “deco” and “micro” embossing patterns. The results indicate that the “micro” embossing process promoted bulky and porous structures, enhancing water absorption capacity and Klemm capillary rise properties, while the “dec” embossing pattern decreased water absorption capacity properties. The creping process also increased the water absorption capacity but decreased Klemm capillary rise properties along with the fiber mixtures. Regarding the liquid spreading kinetics, both embossing patterns decreased this property in uncreped isotropic structures, contrary to creped anisotropic structures. The eucalyptus and softwood fibers mixture improved the spreading kinetics compared to the creping process. The performance of structures with and without embossing allowed to quantify the liquid retention properties, combining ISO experimental methods and an optical system that records the liquid interaction with fibrous structures. In conclusion, this laboratory embossing method can be used as an alternative method to optimize converting operations and the final tissue paper characterization, on a laboratory scale.

Nanozymes are nanomaterials that possess intrinsic enzyme mimicking activity. In this study, the application of silver nanoparticles coated filter paper (AgNPs/FP) that exhibits a peroxidase-like catalytic activity as a potential sensor is reported. A simple chemical reduction method was used to produce AgNPs/FP. The formation of the particles on filter paper were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface-enhanced Raman spectroscopy (SERS). In the presence of hydrogen peroxide, AgNPs/FP oxidized the colorless o-phenylenediamine (OPD) and 3,3′,5,5′-tetramethylbenzidine (TMB) solutions to a yellow colored 2,3-diaminophenazine (DAP) and deep blue colored oxidized TMB (oxTMB), respectively. In the presence of thiocyanate, however, the peroxidase-like activity was inhibited in a concentration dependent manner. This makes the AgNPs/FP a promising catalyst and employed for colorimetric detection of thiocyanate via inhibition of the peroxidase-like activity. The application can be further extended to other environmentally and biologically important analytes.

The blend (wax M) of crude by-product polyolefin wax (wax K) and a fractionated commercial paraffin wax (wax J) was suggested to replace the wax J as a coating agent for wax-coated papers. The rheological properties of waxes J, K, and M were examined and compared. The correlation between viscosity and shear rate applied on these waxes maintained at 90 oC and 130 oC was identified. In particular, this paper, for the first time, presented non-Newtonian shear thinning behavior of not only wax K but also its blend of wax M in terms of their viscosity affected by shear rate at an operating temperature below their melting temperature of higher-melting-temperature DSC endothermic peaks (HMTEPs). They showed non-Newtonian behavior, so-called shear thinning behavior, at 90 oC in the light of characteristics of both suspension systems and polymer systems. In addition, the profiles of viscosity at 130 oC of all the waxes versus the shear rate exhibited Newtonian fluid behavior. Wax J also showed the behavior of a dilatant fluid. Then, the physical properties including water vapor transmission rates (WVTR), surface roughness, and coated weights, of thin papers coated with waxes J (WJP), K (WKP), and M (WMP) were evaluated, characterized, and compared. As a result, WMP had an equivalent value to that of WJP or the lowest value among wax-coated papers in terms of WVTR. The surface roughness and the barrier property of WVTR were minimized and enhanced, respectively, by blending waxes J and K. The additional physical properties, including dynamic contact angles, surface tension, wet and dry tensile strength, optical examination of the wax-coated fiber structure, and antimicrobial properties of the wax-coated papers, were evaluated. The excellent antimicrobial properties of clinoptilolite added to wax J or wax M appeared.

The pursuit for sustainability in the papermaking industry calls for the elimination or reduction of synthetic additives and the exploration of renewable and biodegradable alternatives. Cellulose nanofibrils (CNFs), due to their inherent morphological and biochemical properties, are an excellent alternative to synthetic additives. These properties enable CNFs to improve the mechanical, functional, and barrier properties of different types of paper. The nanosize diameter, micrometre length, semicrystalline structure, high strength, and modulus of CNFs have a direct influence on the mechanical properties of paper, such as tensile index, burst index, Scott index, breaking length, tear index, Z-strength, E-modulus, strain at break, and tensile stiffness. This review details the role played by CNFs as an additive to improve strength properties of paper and the factors affecting the improvement in paper quality when CNFs are added as additives. The paper also includes techno-economic aspects of the process and identifies areas that need further research.

The freshness indicator can detect the freshness of food through characteristic color changes, and has the advantages of high accuracy and visualization. However, existing freshness indicators cannot achieve low-cost mass production. Addressing this challenge, a printed colorimetric freshness indicator which can be used into the modified atmosphere packaging (MAP) of grass carp for freshness monitoring is developed. A printable ink based on natural purple cabbage pigment, carboxymethyl cellulose, and glycerin was prepared, then it was printed in the paper by screen printing and applied to MAP. Additionally, the indicator labels were used in an application trial, which was conducted to monitor the freshness of grass carp under refrigeration (4°C) and at room temperature (25°C). The color response of freshness label was consistent with the spoilage threshold of total volatile basic nitrogen (TVB-N) and trimethylamine (TMA) content in fish sample. Therefore, the paper-sensor label can be used as a simple and practical indicator for freshness monitoring of grass carp.

Graphene paper with good mechanical strength, flexibility, and high conductivity is an emerging functional material for wide applications, but its feasible and scalable preparation remains a challenge. Herein, a high strength, flexible, and conductive graphene/polypropylene (PP) fiber paper was prepared by a traditional papermaking process. In the composite paper, graphene nanosheets were well stabilized on the PP fibers forming a stable three-dimensional conductive interleaved network. Chitosan was found able to build a polar active interface on PP fibers and graphene nanosheets, which can not only promote PP fiber dispersion in water yielding a uniform pulp, but also favor the retention of graphene in the composite paper. As a result, the composite paper presents high strength (15.32 MPa), good conductivity (11,995 S/m), shielding effectiveness (31.1 dB), water resistance, fungi-proof, and thermal conductivity (10.17 W m−1 k−1) properties. This work demonstrates the feasibility of large-scale preparation of graphene composite paper with commercial synthetic fibers through a traditional papermaking process, and expands the potential industrial application of graphene materials. Graphene/chitosan co-aggregates were absorbed on the surface of graphene/chitosan/PP fiber under the electrostatic interaction of CPAM to form graphene/PP fiber.

Iron is an important micronutrient involved in several mechanisms in the human body and can be an important biomarker. In this work, a simple and disposable microfluidic paper-based analytical device (µPAD) was developed for the quantification of iron in urine samples. The detection was based on the colorimetric reaction between iron(II) and bathophenanthroline and the reduction of iron(III) to iron(II) with hydroxylamine. The developed µPAD enabled iron determination in the range 0.07–1.2 mg/L, with a limit of detection of 20 µg/L and a limit of quantification of 65 µg/L, thus suitable for the expected values in human urine. Additionally, targeting urine samples, the potential interference of the samples color was overcome by incorporating a sample blank assessment for absorbance subtraction. Stability studies revealed that the device was stable for 15 days prior to usage and that the formed colored product was stable for scanning up to 3 h. The accuracy of the developed device was established by analyzing urine samples (#26) with the developed µPAD and with the atomic absorption spectrometry method; the relative deviation between the two sets of results was below 9.5%. Graphical abstract: [Figure not available: see fulltext.]

The adsorption of locust bean gum (LBG) onto Northern Bleached Softwood Kraft (NBSK) pulp improved paper tensile and burst strength and lowered refining energy by strengthening inter-fibre bonding. Adsorption kinetics and isotherms were investigated to develop a fundamental understanding of the adsorption mechanism. The adsorption rate followed pseudo-second-order kinetics and the activation energy was 99.34 kJ·mol−1, suggesting chemisorption. The adsorption rate constant increased rapidly with temperature from 25 to 45 °C (k = 1.93 to 24.03 g·mg−1·min−1), but the amount adsorbed at equilibrium decreased (qe = 1.91 to 0.48 mg·g−1 o.d. fibre). LBG adsorption to NBSK at 25 °C was consistent with the Langmuir adsorption model for LBG n = 5.00, and the equilibrium constant Kf = 2.57 mg·g−1·(mg·L−1)−1/n at 25 °C. Favorable adsorption conditions for negatively charged LBG were identified: 25 °C for 10 min, low dosage level ( 150 r.p.m.), acidic or neutral conditions (pH 2–7) without salt addition. Graphic abstract

The pulp and paper industry discharges massive amount of wastewater containing hazardous organochlorine compounds released during different processing stages. Therefore, some cost-effective and nonpolluting practices such as enzymatic treatments are required for the potential mitigation of effluents released in the environment. Various xylanolytic enzymes such as xylanases, laccases, cellulases and hemicellulases are used to hydrolyse raw materials in the paper manufacturing industry. These enzymes are used either individually or in combination, which has the efficient potential to be considered for bio-deinking and bio-bleaching components. They are highly dynamic, renewable, and high in specificity for enhancing paper quality. The xylanase act on the xylan and cellulases act on the cellulose fibers, and thus increase the bleaching efficacy of paper. Similarly, hemicellulase enzyme like endo-xylanases, arabinofuranosidase and β-d-xylosidases have been described as functional properties towards the biodegradation of biomass. In contrast, laccase enzymes act as multi-copper oxidoreductases, bleaching the paper by the oxidation and reduction process. Laccases possess low redox potential compared to other enzymes, which need some redox mediators to catalyze. The enzymatic process can be affected by various factors such as pH, temperature, metal ions, incubation periods, etc. These factors can either increase or decrease the efficiency of the enzymes. This review draws attention to the xylanolytic enzyme-based advanced technologies for pulp bleaching in the paper industry.

Free-standing reduced graphene oxide (rGO) papers were prepared by chemical reduction, thermal reduction and combined chemical-thermal reduction, respectively. Four-point probe and nanoindentation experiments were conducted to investigate the electrical and mechanical properties of rGO papers. The rGO paper prepared by soaking in L-ascorbic acid and thermal annealing in argon at 1000 °C (labeled rGO-AsA-T) showed superior electrical and mechanical properties when compared with rGO papers prepared merely by chemical reduction or thermal reduction. The as-prepared rGO-AsA-T paper exhibited an electrical conductivity of 5.7 × 104 S/m, showing an increase of 90% compared to that in the thermally annealed rGO paper and nearly 40 times that of rGO paper reduced by L-ascorbic acid. It was also found that the rGO-AsA-T paper had the lowest elastic modulus of 288 MPa, showing enhanced flexibility. The nearly free voids in rGO-AsA-T paper proved by scanning electron microscopy (SEM) were due to the capillary action in chemical reduction and were significant in improving the electrical conductivity and flexibility of the paper. The rGO-AsA-T paper with high conductivity and flexibility has a promising application in flexible electronics.

We aimed at producing sodium carboxymethylcellulose (CMC) from waste paper cellulose. For this etherification, the raw material was waste paper, the cellulose was initially alkalized with NaOH, the etherifying agent was sodium chloroacetate, and the reaction medium was water or ethanol. The method provided by us, i e, a method for preparing CMC from waste paper, was environment-friendly, could be easily implemented, and could be conveniently applied to make waste paper efficiently used with high profit, and to expand the range of usable raw materials for CMC production. We successfully synthesized CMC and prepared CMC plastic membrane. This practice changes waste into valuables, which is beneficial to our living environment. For preparation of CMC, one of the crucial factors is appropriate pretreatment of the cellulose from waste paper. The pretreatment was done with a self-built hydrolysis method. We experimentally examined the effects of the mass ratios of reactants, reaction temperature, time, and reaction environment of homogeneous or heterogeneous on CMC yield. The innovative points of this research could be stated as follows: the reaction activity of cellulose was improved by pre-hydrolysis; synthesizing CMC with cellulose from waste paper changes waste into valuables is beneficial to our living environment; and a freezing treatment for the cellulose-alkali mixture was innovatively added. The effects were exhibited by a desired final conversion efficiency.

High per- and polyfluorinated alkyl substance (PFAS) concentrations have been detected in agricultural soils in Southwest Germany. Discharges of PFAS-contaminated paper sludge and compost are suspected to be the cause of the contamination. Perfluorinated carboxylic acids (PFCAs) have been detected also in groundwater, drinking water, and plants in this area. Recently, previously unknown compounds have been identified by high-resolution mass spectrometry (HRMS). Major contaminants were polyfluorinated dialkylated phosphate esters (diPAPs) and N-ethyl perfluorooctane sulfonamide ethanol–based phosphate diester (diSAmPAP). In this study, HRMS screening for PFAS was applied to 14 soil samples from the contaminated area and 14 impregnated paper samples which were from a similar period than the contamination. The paper samples were characterized by diPAPs (from 4:2/6:2 to 12:2/12:2), fluorotelomer mercapto alkyl phosphates (FTMAPs; 6:2/6:2 to 10:2/10:2), and diSAmPAP. In soil samples, diPAPs and their transformation products (TPs) were the major contaminants, but also FTMAPs, diSAmPAP, and their TPs occurred. The distribution patterns of the carbon chain lengths of the precursor PFAS in soil samples were shown to resemble those in paper samples. This supports the hypothesis that paper sludge is a major source of contamination. The presence of major degradation products like PFCAs, FTSAs, or PFOS and their distribution of carbon chain lengths indicate the activity of biotic or abiotic degradation processes and selective leaching processes from the upper soil horizons. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00216-021-03463-9.

Infections caused by resistant microorganisms are a complex global public health challenge, and the way to combat the increase of resistance is the development of more modern and faster techniques for resistance detection. This study aimed to evaluate the transport of inactivated bacteria impregnated in a filter paper disk to detect carbapenem resistance genes by multiplex real-time PCR (qPCR) using high-resolution melting (HRM). A total of 88 isolates of 10 different species of Enterobacterales harboring well-characterized carbapenem resistance genes were evaluated. A full 10-µL loop of fresh growth of bacteria were impregnated in a filter paper disk, which was left at room temperature for 2 days in order to simulate the time spent in transportation. Bacterial inactivation was performed with 70% ethanol at 15 min. Afterwards, the DNA was extracted from the paper disks for further analysis by qPCR HRM. The time of 15 min in 70% ethanol was enough to inactivate all the isolates tested. It was possible to correctly identify the presence of the carbapenem resistance gene by HRM qPCR in 87 isolates (98.87%) that were transported in the filter paper disks. Our results indicated that it is possible to use filter paper to transport inactivated bacteria and to identify carbapenem resistance genes by qPCR HRM. This alternative tends to facilitate the access to this technology by many laboratories which do not have the qPCR equipment.

The potential of alkaline cellulo-xylanolytic enzymes from non-pathogenic Bacillus subtilis strain was tested for deinking of photocopier waste paper. Cellulase and xylanase play a crucial role in deinking of different types of waste paper. Partial purification of cellulo-xylanolytic enzymes was carried out using ultrafiltration followed by ammonium sulfate precipitation. The ultrafiltered enzyme was used for deinking the photocopier waste paper along with chemical deinking. An enzyme dose of 0.6 IU/g and reaction time of 60 min for ultrafiltered cellulo-xylanolytic enzyme significantly increased deinking efficiency, tear index (9.52%) and folding endurance (5±2%) as compared to chemical deinking. There was improvement in strength properties such as tear index and double-fold along with freeness of pulp (18%). There was slight decrease in tensile index (0.6%) and burst index (16%) while ISO brightness remained unaffected. Enzymatic deinking (74.3%) by ultrafiltered cellulo-xylanolytic from Bacillus subtilis was found significant over conventional chemical deinking.

In this research work, we present a synthesis of silver and cobalt bimetal nanoparticles stabilized by a carboxymethyl cellulose biopolymer (CMC-AgCo) and its coating on a cellulose filter paper (CFP) to prepare the dip-catalyst. All the prepared samples were subjected to characterization by scanning electron microscopy for surface morphology, EDX, XRD and thermogravimetric analysis. The catalytic properties of the CFP/CMC-AgCo as dip-catalysts were evaluated in the reduction of organic nitroaromatic pollutants of 2,6-dinitrophenol to 2,6-diaminophenol as well as the 4-nitrophenol to 4-aminophenol. It was found that the reduction reaction advanced with the pseudo-first-order kinetics. The CFP/CMC-AgCo catalyzed the 2,6-diaminophenol and 4-nitrophenol with a reaction rate constant of 0.1244 and 0.177 min− 1, respectively. The separation of the CFP/CMC-AgCo was easy as it required a simple pulling of the strip from the reaction medium. Importantly, the catalytic reaction rates and conversion percentages of the two nitroaromatics were well-maintained for multiple times during recycling experiments.

The increasing demand for food and the need for a sustainability vision in the agri-food sector have boosted novel approaches for food management, enhancing the valorization of wastes and by-products belonging to the food industry. Herein, we present a novel paper-based origami device to assess the amount of both glucosinolate and glucose in a food waste product belonging to Brassicaceae plants, to evaluate the quality value and the correct management of waste samples. The device has been designed as an origami paper-based platform constituted of two paper-based biosensors to work synergistically in a multiplexed detection. In detail, a monoenzymatic biosensor and a bienzymatic biosensor were configured for the detection of glucose and glucosinolates, respectively, using filter paper pads preloaded with glucose oxidase and/or myrosinase. To complete the paper-based platform, the enzyme-preloaded pads were combined with office paper-based electrodes modified with Carbon black/Prussian Blue nanoparticles for the measurement of enzymatic by-product at a low applied potential (i.e., 0 V versus Ag/AgCl). Overall, this paper-based platform measured glucose and glucosinolate (i.e., sinigrin) with a linear range up to 2.5 and 1.5 mM, and detection limits of 0.05 and 0.07 mM, respectively. The repeatability corresponded to an RSD% equal to 5% by testing 10 mM of glucose, and 10% by testing 1 mM of sinigrin. The accuracy of the developed multiplex device was evaluated by recovery studies at two different levels of sinigrin, i.e., 0.25 and 0.5 mM, obtaining recoveries values equal to (111 ± 3) % and (86 ± 1) %, respectively. The multiplex detection of both glucose and glucosinolate in Brassicaceae samples evaluates the quality values of the waste sample, ensuring the quality of the re-used food product waste by using an eco-designed analytical tool. The combination of paper-based devices for quality control of food waste with the re-use of these food products represents a sustainable approach that perfectly matches sustainable agrifood practices as well as the overall approach of the circular economy. Graphical abstract

The outbreak of new viral strains promotes advances in universal diagnostic techniques for detecting infectious diseases with unknown viral sequence. Long double-stranded RNA (dsRNA), a hallmark of infections, serves as a virus marker for prompt detection of viruses with unknown genomes. Here, we report on-chip paper electrophoresis for ultrafast screening of infectious diseases. Negatively charged RNAs pass through the micro and nanoscale pores of cellulose in order of size under an external electric field applied to the paper microfluidic channel. Quantitative separation of long dsRNA mimicking poly I:C was analyzed from 1.67 to 33 ng·μL−1, which is close to the viral dsRNA concentration in infected cells. This paper-based capillary electrophoresis chip (paper CE chip) can provide a new diagnostic platform for ultrafast viral disease detection at the point-of-care (POC) level.

Environmental and health concerns are driving food packaging to reduce the use of poly- or perfluorinated compounds and petroleum-based polymers. Here, we successfully obtained good oil-proof paper by combining cellulose nanofibril (CNF) film with filter paper through film transfer. The process was not only facile but also did not require chemical reagents other than water. To achieve the kit number 12, the basis weight of the CNF film was 2.1 g/m2, which was much less than the amount required for coating. The calendering process further reduced the pores thus improving the oil resistance of the film transfer paper. At a calendering pressure of 20 N/mm, only 1.4 g/m2 of the CNF film was required for kit number 12. This study provides a new way for the application of CNF in the field of oil resistance.

We demonstrated the thermally robust reduced graphene oxide (rGO)/boron nitride nanotube (BNNT) papers and their application in electromagnetic interference shielding. In order to overcome the thermal durability shortcomings of electromagnetic wave shielding paper based on rGO nanomaterial, rGO/BNNT electromagnetic interference (EMI) shielding paper having excellent thermal durability could be manufactured using BNNT nanomaterials having excellent chemical and thermal stability at high temperature. With the addition of a little BNNT, the durability against temperature can be increased by more than two times while there is little reduction in EMI performance.

The purpose of this study was to investigate the impact of mLearning or mobile device practice on the attention and accuracy of student's use of math concepts, specifically, telling time. A single subject, alternating treatment design was used to compare mLearning to paper and pencil practice in four 3rd grade male students. Results were mixed; two children were observed to be more on-task during the mLearning practice, and two children were observed to perform similarly across both conditions. Additionally, two children performed similarly on correctly completed problems across both conditions, and two children performed better using paper and pencil practice. All students completed more math problems during the paper and pencil practice.

Excellent mechanical and electrical properties of graphene-based paper-like materials are essential for applications in flexible conductors, energy-storage devices, etc. The graphene oxide (GO) supernatant separated by centrifugation and ultrasonication has been used to prepare graphene oxide paper and reduced graphene oxide paper (rGOP) with high strength and conductivity. However, this method has cumbersome steps and low supernatant concentration, which greatly increases time and energy consumption, and is not suitable for rapid batch preparation of high-strength and high-thickness rGOP. Herein, a high-speed mechanical shearing method has been used to efficiently exfoliate graphite oxide suspension into high-concentration GO slurry with large lateral size, and rGOP has been further prepared by blade coating and HI acid chemical reduction. Compared with the product prepared by ultrasonic exfoliation method, the average area of GO sheets obtained via the mechanical shear exfoliation method can reach around 16.31 μm2. As a result, the mechanical properties and conductivity of the prepared rGOP have been increased by 30% and 23.5%, respectively, with the tensile strength and electrical conductivity of 478.2 MPa and 208.4 S/cm being obtained. The developed method is of great significance for the large-scale production and emerging applications of lightweight and high-performance rGOP.

The impact of volatile organic compounds (VOCs) and odor on indoor environment and people has attracted much attention. To reduce this problem of odorous compounds contained in wood panel, this study focused on identifying odorant compounds and exploring the influence of moisture content factors on VOCs and odor emissions. Paper mulberry (Broussonetia papyrifera (L.)Vent.) was investigated using the technology of gas chromatography-mass spectrometry/olfactory (GC–MS/O). Total volatile organic compounds (TVOC) and characteristic odor-active compounds were studied, and the emission of heartwood and sapwood of paper mulberry was compared at the same time. It was found that the main components from heartwood and sapwood were aromatics, alkanes, alkenes, aldehydes ketones, alcohols and esters. Totally, 23 kinds of odor-active compounds were identified from heartwood and sapwood of paper mulberry, among which, aromatics and aldehydes ketones were the main odorant compounds. Seven kinds of key odorant compounds were identified in this process. With the decrease in moisture content, the TVOC and total odor intensity of heartwood and sapwood generally decreased. The moisture content had a great effect on VOC release when the moisture content decreased from 70 to 50% and reduced from fiber saturation point (30%) to air saturation point (10%). The main odor impressions of paper mulberry were aromatic, fresh fruit fragrance, sweet scent and special pungent. In the whole process of moisture content decrease, the TVOC, concentration of odorant and odor intensity of sapwood were higher than that of heartwood.

Graphical abstract Enzyme-linked immunosorbent assay (ELISA) is widely used for the detection of disease biomarkers. However, it utilizes time-consuming procedures and expensive instruments, making it infeasible for point-of-care (POC) analysis especially in resource-limited settings. In this work, a multicolorimetric ELISA biosensor integrated on a paper/polymer hybrid microfluidic device was developed for rapid visual detection of disease biomarkers at point of care, without using costly equipment. This multicolormetric ELISA platform was built on multiple distinct color variants resulted from the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and the etching of gold nanorods (AuNRs). The vivid color changes could be easily distinguished by the naked eye, and their red mean values allowed quantitative biomarker detection, without using any sophisticated instruments. When this multicolorimetric ELISA was integrated on a paper/polymer hybrid analytical device, it not only provided integrated processing and high portability but also enabled fast assays in about 50 min due to the unique advantages of paper/polymer hybrid devices. The limit of detection of 9.1 ng/μL of the hepatitis C virus core antigen, a biomarker for hepatitis C, was achieved using this multicolorimetric ELISA platform. This multicolor ELISA analytical device provides a new versatile, user-friendly, affordable, and portable immunosensing platform with high potential for on-site detections of various viruses, proteins, and biomarkers for low-resource settings such as at home, public venues, rural areas, and developing nations. Supplementary Information The online version contains supplementary material available at 10.1007/s00216-021-03359-8.