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The construction industry had approached a critical limit which led to the increase of cement production. The production of cement would cause a broader environmental implication. Cement production is a major source of carbon dioxide emission. Carbon dioxide gas contributes about 63.33% of global warming since the production of one ton of cement would emit about one ton of carbon dioxide to the environment. To mitigate this issue, the research community has investigated the use of waste materials that possess similar chemical properties with cement content as a material for partial cement replacement. The use of rice husk ash has shown to be a contending candidate in the literature. Therefore, this paper attempts at reviewing the performance of rice husk ash as partial cement replacement. It could be observed from the literature that concrete with 5% up to 15% of rice husk ash showed an equivalent performance to ordinary concrete in compressive, flexural, and tensile strength. Thus, rice husk ash can be used as a material replacement in concrete and reduces pollution that originates from cement production and open burning of rice husk.

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

Graphene-based nanomaterials possess broad applications because of their excellent multi-functional properties. In this work, a facile self-assembling method was presented for preparing one kind of graphene oxide-based paper/hollow microspheres hybrid. It was found that most of the hollow microspheres can strongly anchored on the surface of graphene oxide paper (GOP) by an in-situ scanning electron microscope peeling testing combining with molecular dynamics (MD) simulation. In addition, the uniform distribution of hollow microspheres on the surface of GOP cannot only provide a better surface wettability, but also can effectively improve the interfacial stress-transfer capability between such hybrid and polymer matrix. Our work provides a guidance for the structural designs of graphene-based nanomaterials and broaden their applications.

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

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

While basic concepts of paper-based microfluidic analytical devices (μPADs) have appeared considerably, elemental technology development is worth working from different specialized points of view. Herein, we show that 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofiber (TOCN) can be reasonably used as a module of μPADs; we adopted a biochemical reaction of indigo formation by oxidation of indoxyl acetate (IDA) via its hydrolysis with acetylcholinesterase (AChE) as an example. First, we demonstrate that TOCN stably stores unstable AChE and IDA when dried and acts as a biochemical reaction field when wet. The thixotropic nature of TOCN aqueous dispersion gave inkjet printability, which will facilitate the μPADs production. The exchange of substances in the wet TOCN network took more time than in solution, but this can be read as control of reaction kinetics. Finally, we constructed semiquantitative μPADs for an organic phosphorus pesticide. We illustrate that by mounting TOCN, various functions can be incorporated on one sheet of paper to lead to the extension of design flexibility and universal use for μPADs.

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

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

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

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

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

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

Micro-cracks are inherently present in concrete, leads to debilitation of structures. Methods used for managing micro-cracks have a certain degree of toxicity and also possesses certain drawbacks that made them not completely efficient. Bacterial technique when used in fresh concretes results in calcite precipitation in voids and consequently improves the strength and lowers permeability of concrete. Bio- cement is the combination of Bacillus pasteurii 5% and nutrients Urea, Calcium Lactate 95%. In this study by adding 0.5, 1, 1.5 and 2% Bio- cement by weight of cement and observed compressive strength, flexural strength values after 7 and 28 days of curing for M25 grade of concrete.

Writing and presenting results is important for any research work. Publishing is not enough; it should be written clearly and consistently for others to read and cite. We present a review of different techniques, for improving the writing in research papers intended for publishing. These include how to write the title, whether to use active or passive voice, how long sentences should be, how to present the uncertainty, understanding the International System of Units (SI) writing conventions, how to assign authorship, how to effectively use references, how to present the work, and how to publish it in a journal. This paper is a summary of the main and most recent recommendations in the scientific field on how to write a research paper to increase its impact.

Supercapacitors are favored by researchers because of their high power density, especially with the acceleration of people's life rhythm. However, their energy density, especially from the point of view of the whole energy storage device, is far lower than that of commercial batteries. In this work, a kind of customizable full paper-based supercapacitor device with excellent self-healing ability is fabricated by simple and low-cost screen printing, electropolymerization and dip coating methods. The resultant separator-free supercapacitor device exhibits both ultrahigh gravimetric and areal specific energy (power) densities of 39 Wh kg−1 (69 kW kg−1) and 692 μWh cm−2 (236 mW cm−2), achieving excellent supercapacitor performance. Notably, the addition of vitrimers endows the whole device with outstanding self-healing properties, which is helpful for enhancing the adaptability of the device to the environment. In addition, this kind of paper-based device also displays good photothermal and electromagnetic shielding performances. These striking features make paper matrix composites attractive in the fields of supercapacitors, medical photothermal treatment and electromagnetic shielding.

Diesel Particulate filters are considered one of the most efficient technologies to reduce particulate matter emitted by diesel engines. In this paper we study the development of catalytic ceramic papers based on Mn-Ce and their applications as soot particle filters in bench scale tests. Ceramic papers were prepared by a dual polyelectrolyte papermaking method and were impregnated with Mn and Ce precursors through a wet-spray procedure using a commercial fogger. Catalytic ceramic papers were tested as catalysts for the combustion of soot, which was obtained both from the burning of diesel fuel and directly from a bench test. In addition, the filtering capacity of catalytic ceramic papers was tested through opacity measurements by placing the ceramic papers in a suitable case at the end of the engine. Mn-Ce based catalysts were active in the soot combustion. The addition of citric acid considerably improved the catalytic performance of all the systems studied. This beneficial effect of citric acid is related to an improvement in the distribution of the catalytic material onto the ceramic fibers, being the mixed equimolar oxide Mn-Ce the most active catalyst.

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10606) demonstrated that the interaction between H2 and MXene (Sc2C and Ti2C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc2C and Ti2C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc2C and Ti2C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti2C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti2C, Sc2C and their oxygen-functional counterparts, the binding energy of H2 on Sc2CO2 surface is the closest to the ideal range of 0.16–0.42 eV/H2 at ambient conditions, and thus the Sc2C with oxygen group is expected to be more suitable as hydrogen storage materials.

In recent times, it has been witnessed that wireless systems based on IoT-based have developed rapidly in various sectors. The IoT (Internet of Things) is the network in which physical devices, equipment, sensors and other objects can communicate among themselves without human involvement. The WSN (Wireless Sensor Network) is a central component of the IoT, which has proliferated into several different applications in real-time. The IoT and WSNs now have various critical and non-critical applications impacting nearly every area of our everyday life. WSN nodes are usually small and battery-driven machines. Thus, the energy effective data aggregation techniques that increase the lifespan of the network are highly significant. Various approaches and algorithms for energy-efficient data aggregation in IoT-WSN systems were presented. This paper reviews the literature with specific attention to aspects of wireless networking for the preservation of energy and aggregation of data.

Photonic crystals film that possesses periodic dielectric structure have shown great prospect in developing environmentally friendly paper alternatives due to the unique properties of dye free and non-photobleaching, but their practical application is limited by the weak interaction between colloidal particles. Although some progress has been obtained, it is still a challenge to develop photonic paper with the desired mechanical and optical properties. Herein, multifunctional hard core/soft shell nanoparticles with controlled size are fabricated by semi-continuous seed emulsion polymerization method. Compared with convention colloidal particles, these core/shell nanoparticles can facile self-assemble into large-scale dense ordered structure film via dried at room temperature due to the relatively low glass transition temperature (Tg) of the shell layers. The facile fabrication route enables the continuous high-through put production of the photonic papers. The as-formed papers not only possess the capacity to solvent (water/ethanol) rewritable and multicolor painting, but also can rapidly reversible mechanochromic. Moreover, due to the good compatibility of core/shell interface, these photonic films possess excellent mechanical properties, demonstrating that this multifunctional film makes the fabrication of novel robust rewritable papers possible and enables visual monitoring of deformation degree.

Highlights • Numerical simulations of acoustophoresis in pulp flow is conducted. • Parametric study of fiber characteristics, pulp flow regimes and acoustic parameters are conducted. • A feasibility study of industrial acoustophoresis for pulp concentration is performed. • A potential concentration gain of 15% is obtained experimentally., In pulp and paper mills, mechanical processes such as screening and washing are commonly used to remove accumulated solid suspensions and concentrate the pulp. For environmental reasons and to optimize paper production, an emerging challenge is to develop alternative methods to concentrate paper pulp between 3 % and 6 % consistency for which the mixed pulp-water flow is complex. Among the proposed solutions in the literature, solutions based on acoustic levitation, also referred as acoustophoresis, of low-consistency pulp have been demonstrated as a potential solution for efficient pulp concentration and water recirculation. However, no sensitivity analysis on the ultrasound and physical parameters was proposed, limiting the extension to a realistic application. Thus, this paper presents a numerical modeling of acoustophoresis for pulp flow concentration in a pipe. For this purpose, the pulp flow is defined as a pseudo-homogenous fluid with a turbulent Low Re k- ∊ formalism, and the pulp particles are considered spherical and deflected by two acoustic forces, namely the acoustic radiation force and the Stokes drag force, both induced by an ultrasound wave generated along the walls of a circular pipe. The combined action of these two forces in the pulp flow enables to concentrate the particles at the center of the pipe. The influences of particle size and mechanical properties, fluid properties and ultrasound parameters are analyzed within a parametric study to optimize the particle deflection and the pulp concentration. The experimental feasibility of the industrial use of acoustophoresis for the concentration of paper pulp is demonstrated with a concentration gain up to 15 %.

International audience; Despite predictions of the paperless office, global demand for printing and writing paper remains strong, and paper appears to be here to stay for some time. Not only firms, but also governments, libraries, and archives are in possession of large collections of legacy documents that still must be sorted and scanned. In this study, terahertz-based techniques are demonstrated to address several routine tasks related to the automated paper handling of unsorted legacy documents. Specifically, we demonstrate terahertz-based counting of the number of sheets in unconsolidated paper stacks, as well as locating stapled documents buried in paper stacks.

The limited CO2 content in aqueous solution and low adsorption amount of CO2 on catalyst surface lead to poor photocatalytic CO2 reduction activity and selectivity. Herein, the design and fabrication of a novel photocatalytic architecture is reported, accomplished via chemical vapor deposition of polymeric carbon nitride on carbon paper. The as-obtained samples with a hydrophobic surface exhibit excellent CO2 transport and adsorption ability, as well as the building of triphase air-liquid-solid (CO2-H2O-catalyst) joint interfaces, eventually resulting in the inhibition of H2 evolution and great promotion of CO2 reduction with a selectivity of 78.6%. The addition of phosphate to reaction environment makes further improvement of CO2 photoreduction into carbon fuels with a selectivity of 93.8% and an apparent quantum yield of 0.4%. This work provides new insight for constructing efficient photocatalytic architecture of CO2 photoreduction in aqueous solution and demonstrates that phosphate could play a key role in this process.

Ambient ionization of glycans is simply and efficiently achieved by spraying from an alkali metal salt-impregnated paper surface. Monosaccharides, oligosaccharides and ring glycans easily form abundant alkali metal adduct ions, and give simple and clean high-quality mass spectra. The enhancement is specific for glycans, compared to a wide variety of non-glycan compounds present in a matrix. In addition, molecular weight of unknown glycans can be further identified based on the ion mass difference of various alkali metal adduct ions from a certain compound when using a mixed salt-impregnated paper containing five cation salts. Successful determination of glycans and glycoconjugates in plant extracts, honey, blood and urine demonstrates the practicability of this approach to complicated matrices, especially biological matrices.

Thermal papers are replacing the conventional form of printing and are being extensively used across the globe. This study encompasses a non-destructive approach to examine thermal papers by using ATR-FTIR spectroscopy and Video Spectral Comparator (VSC), where the former technique helps in characterizing and discriminating different samples and the latter helps in deciphering the faded prints on thermal paper. The qualitative analysis of the spectroscopic data based on peak to peak comparison and quantitative analysis using chemometrics has been done to obtain high discriminating power. Multivariate analysis using HCA gave a discriminating power of 83.82% and PCA showed a variance of 95.64%. The strength of the study is portrayed through the decipherment of artificially and naturally faded thermal papers using VSC and analyzing the effect of different storing conditions on their rate of fading.

The development of low-cost analytical devices for on-site water quality monitoring is a critical need, especially for developing countries and remote communities in developed countries with limited resources. Microbial electrochemical cell-based (MXC) biosensors have been quite promising for quantitative and semi-quantitative (often qualitative) measurements of various water quality parameters due to their low cost and simplicity compared to traditional analytical methods. However, conventional MXC biosensors often encounter challenges, such as the slow establishment of biofilms, low sensitivity, and poor recoverability, making them unable to be applied for practical cases. In response, MXC biosensors assembled with paper-based materials demonstrated tremendous potentials to enhance sensitivity and field applicability. Furthermore, the paper-based platforms offer many prominent features, including autonomous liquid transport, rapid bacterial adhesion, lowered resistance, low fabrication cost (

Effluent discharged from paper industries has an unfavourable impact on all the biotic and abiotic components of the environment due to the presence of various bio-recalcitrant toxic compounds. Multiple physico-chemical treatment systems have been adopted over the last two decades for the elimination of refractory organics from paper industry effluent but with limited success. Augmentation of biological treatment through metabolic and cometabolic strategies seems to be a promising and sustainable option. This article aims at presenting a comprehensive account of treating the paper industry effluent with existing treatment strategy using potent green agents through bioaugmentation and mineralization of chlorophenols via ortho- and meta- pathways. Sequential treatment based on consortia of specialized microorganisms remove > 90% of different toxic and recalcitrant compounds present in paper industry effluent. The rapid technological development in microbial fuel cells holds the potential for simultaneous paper industry effluent treatment and energy production.

In this work, ZnO nanorods (ZnO NRs) with different sizes were hydrothermally grown on the surface of Whatman filter paper for the fabrication of a microfluidic paper-based device (μPAD) for the simultaneous detection of glucose and uric acid. As dual enzymatic reaction was employed for the colorimetric detection in this μPAD, the presence of ZnO NRs promoted the enzyme immobilization thus significantly enhancing the colorimetric signal. The coffee ring effect was effectively conquered by the uniform distribution of ZnO NR as well as a specialized double-layered μPAD design. Meanwhile, two color indicators with distinct colors were used to provide complementary results to better quantify the concentration of the analytes by naked eye. As a result, two linear calibration curves were obtained for the detection of glucose (0.01–10 mmol L−1) and uric acid (0.01–5 mmol L−1), along with a LOD of 3 μmol L−1 for glucose and 4 μmol L−1 for uric acid, respectively. The practical usefulness of the proposed μPAD was further validated by the simultaneous analysis of glucose and uric acid in serum samples and urine samples.

Flexible paper-based surface enhanced Raman spectroscopy (SERS) substrate has attracted great attention in the sensitive detection of analytes in recent years. However, due to its inherent hydrophilic surface, the nanoparticles will not be concentrated very well on the surface of the paper. This reduces the reproducibility and sensitivity of the paper-based substrate. Herein, we demonstrate flexible hydrophobic paper-based substrate using silver nanocubes loaded on polymethylhydrosiloxane modified filter paper (AgNCs@SiO2/PMHS modified filter paper) to realize high sensitivity and reproducibility. The hydrophobic filter paper was obtained by dip-soaking the filter paper into PMHS solution, resulting in increased contact angle to ~112.5°. The AgNCs@SiO2/PMHS modified paper substrate shows high analytical enhancement factor (AEF) of 6.55 × 106, which is 2.2-fold enhancement compared to AgNCs@SiO2/normal paper substrate, and a low detection limit of 0.1 nM rhodamine 6G and 0.89 nM adenine. The high SERS enhancement factor and sensitivity is attributed to the high hotspots density created in the hydrophobic surface as a result of the excellent uniformity and superior sample collection efficiency compared to the normal filter paper-based substrate. Besides, the substrate shows excellent spot-to-spot and substrate-to-substrate reproducibility, with relative standard deviation (RSD) of 6.05% and 9.22%, respectively. Moreover, the AgNCs@SiO2/PMHS modified filter paper substrate achieved good stability; the Raman signal intensity only drops by 25.88% after 3 months of exposure to air. Therefore, this flexible hydrophobic AgNCs@SiO2/PMHS modified filter paper substrate with low cost fabrication and label-free SERS detection is a promising SERS platform for analytical and biological sensing applications.

Graphene-based papers have recently triggered considerable interests in developing the application as thermal interface materials (TIMs) for addressing the interfacial heat transfer issue, but their low through-plane thermal conductivity (κ⊥), resulting from the layer-by-layer stacked architecture, limits the direct use as TIMs. Although various hybrid graphene papers prepared by combining the graphene sheets and the thermally conductive insertions have been proposed to solve this problem, achieving a satisfactory κ⊥ higher than that of commercial TIMs (>5 W m−1 K−1) remains challenging. Here, a strategy aimed at the construction of heat pathways along the through-plane direction inside the graphene paper for achieving a high κ⊥ was demonstrated through the simultaneous filtration of graphene sheets with two different lateral sizes. The as-prepared graphene paper presented a hierarchical structure composed of loosely stacked horizontal layers formed by large graphene sheets, intercalated by a random arrangement of small graphene sheets. Due to the heat pathways formed by small graphene sheets along the through-plane direction, the hierarchically structured graphene paper exhibited an improved κ⊥ as high as 12.6 W m−1 K−1 after a common graphitization post-treatment. In the practical test, our proposed paper as an all-graphene TIM achieved an enhancement in cooling efficiency of ≈ 2.2 times compared to that of the state-of-the-art TIM, demonstrating its superior performance to meet the ever-increasing heat dissipation requirement.

Microfluidic paper-based analysis devices (μPADs) have undergone tremendous development in recent years and now provide a feasible low-cost alternative to traditional laboratory tests for the diagnosis of many common diseases and disorders. As such, they are of great interest and importance in developing regions of the world with a lack of medical resources and associated infrastructures. This review examines the advances made in microfluidic paper-based diagnostic technology in the past five years and describes the application of microfluidic paper-based assays to the detection of many common human diseases using 3 non-invasive samples sources such as saliva, tears and sweat. The review commences by introducing the basic principles of fluid transport in microfluidic paper-based devices. The structures and actuation systems used in common paper-based devices are then introduced and explained. A systematic review of recent proposals for the application of paper-based devices to the diagnosis of common human diseases is then presented. The review concludes with a brief discussion of the challenges facing the microfluidics paper-based diagnosis field in the coming years and the emerging opportunities for future research.

We report an approach to waterborne and degradable latex polymers. Emulsion polymerization of vinyl acetate (VA) with the cyclic ketene acetal 2-methylene-1,3-dioxepane (MDO) yields polymer particles and latex-based coatings that are hydrolytically degradable due to the presence of backbone ester groups. Polymerization under mildly basic conditions (pH 8) and at low temperature (40 °C) is critical: if the in-process pH is too acidic or the temperature too high, MDO is lost to hydrolysis, but when the media is too alkaline, VA monomer rapidly hydrolyzes. When coated onto commercial paper, films of these degradable particle dispersions show excellent oil and grease resistance as compared to non-degradable, VA-only compositions. This new class of latex is therefore well-suited for the design of next-generation, biodegradable and compostable single-use food service products, as well as for other applications where the erosion or degradation of polymer-based films and coatings is required.

Uniformly dispersing silver nanowires (AgNWs) in polymer matrices is of paramount importance for developing high-performance electromagnetic interference (EMI) shielding materials. Herein, new flexible and robust high-efficiency bacterial cellulose (BC)-based EMI shielding papers were developed via a modified step-by-step in situ biosynthesis method, in which, AgNWs were well distributed in the BC network. The BC nanofibers and AgNWs could form an effective entangled network with hydrogen bonding, efficiently strengthening the produced BC/AgNW papers. An electrical conductivity of 608365 S m1 was achieved for a BC/AgNW paper with a AgNW content of 36.5 wt%, which is superior to almost all AgNW-containing papers reported so far. Moreover, the BC/AgNW paper could sustain mechanical deformation and vigorous washing, without losing electrical conductivity. Additionally, this paper presents an ultrahigh specific EMI shielding effectiveness of 6400 dB mm1, which is higher than almost all previously reported AgNW-based polymer composites. The proposed approach in this study provides a facile and scalable fabrication route for producing flexible and highly conductive BC/AgNW papers, which are of great potential as electrically conductive components and EMI shielding elements in advanced applications., This work was supported by the National Natural Science Foundation of China (Grant Nos. 51973058 and 31870963), Jiangxi Provincial Natural Science Foundation (Grant No. 20202ACBL214007), Key Research and Development Program of Jiangxi Province (Grant No. 20192ACB80008) and the Key Project of Natural Science Foundation of Jiangxi Province (20202ACBL204013)., info:eu-repo/semantics/publishedVersion

This paper presents a critical review of laser pyrolysis. Although this technology is almost 60 years old, in literature many researchers, both from academia and industry, are still developing and improving it. On the contrary industrial applications are struggling to take off, if not in very restricted areas, although the technology has undoubted advantages that justify future development. The aim of this work consists in analysing a representative pool of scientific papers (230) and patents (121), from the last 20 years, to have an overview about the evolution of the method and try to understand the efforts spent to improve this technology effectively in academia and in industry. This study is important to provide a complete review about the argument, still missing in the literature. The objective is to provide an overview sufficiently broad and representative in the sources and to capture all the main ways in which laser pyrolysis has been used and with what distribution. The main focuses of the study are the analyses of the functions carried out by laser technologies, the application fields, and the types of used laser (i.e. models, power and fluence). Among the main results, the study showed that the main use of laser pyrolysis is to produce nanoparticles and coatings, the main materials worked by laser pyrolysis are silicon and carbon dioxide and the main searched properties in the products of laser pyrolysis are catalysts activity and electrical conductivity. CO2 lasers are the most used and the have high versatility compared to others. In conclusion, the study showed that laser pyrolysis is a consolidated technology within its main application fields (nanoparticles and coatings) for several years. Within this context, the technology has been developed on very different sizes and processes, obtaining a very wide range of results. Finally, these results may also have stimulated new areas of experimentation that emerged mainly in recent years and which concern biomedical applications, additive manufacturing, and waste disposal. Graphical abstract

International audience; We clarify some analytical expressions existing in the literature, • Within the correct formulae we conclude that there is no need for an ad hoc improvement on the opposite to the title paper, • We highlight the symmetry properties of the function to be integrated in order to agree with the usual assumptions made to derive the Kramers-Kronig relations, • The analytical formula we provide may be used to increase the accuracy of the "Poor Man's Kramers-Kronig analysis" method and the "Kramers-Kronig constrained variational analysis" method.

The paper industry is an important sector annually consuming kilotons of nanoforms and non-nanoforms of fillers and pigments. Fillers accelerate the rate of drying (less energy needed) and product cost (increasing the load of low-cost fillers). The plastic industry is another use sector, where coloristic pigments can be in nanoform, and many food containers are made of plastic. Use of paper to wrap both wet and dry food is consumer practice, but not always intended by producers. Here we compare the release behavior of different nano-enabled products (NEPs) by changing a) nanoform (NF) characteristics, b) NF load, c) the nano-enabled product (NEP) matrix, and d) food simulants. The ranking of these factors enables an assessment of food contact by concepts of analogy, specifically via the similarities of the rate and form of release in food during contact. Three types of matrices were used: Paper, plastic ((Polylactic Acid (PLA), Polyamide (PA6), and Polyurethane (PU)), and a paint formulation. Two nanoforms each of SiO2, Fe2O3, Cu-Phthalocyanine were incorporated, additionally to the conventional form of CaCO3 that is always contained in paper to reduce cellulose consumption. Tests were guided by the European Regulation EC 1935/2004 and EU 10/2011. No evidence of particle release was observed: the qualitative similarity (the form of release) was high regarding the food contact of all NEPs with embedded NFs. Quantitative similarity of releases depended primarily on the NEP matrix, as this controls the penetration of the simulant fluid into the NEP. The solubility of the NF and impurities in the simulant fluid was the second decisive factor, as dissolution of the NF inside the NEP is the main mechanism of release. This led to complete removal of CaCO3 in acidic medium, whereas Fe and Si signals remained in the paper, consistent with the low release rates in an ionic form. In our set of 16 NEPs, only one NEP showed a dependence on the REACH NF descriptors (substance, size, shape, surface treatment, crystallinity, impurities), specifically attributed to differences in soluble impurities, whereas for all others the substance of the nanoform was sufficient to predict a similarity of food contact release, without influences of size, shape, surface treatment and crystallinity. European Union [760840] Published version The GRACIOUS project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 760840. We sincerely thank Tim Duncan of the US-FDA for providing specimen of Quantum-Dot-polymer films that enabled benchmarking of our methodology. Hubert Rauscher of EC-JRC and Danail Hristozov of GD are gratefully acknowledged for critical presubmission review. We thank Kai Werle and Svenja Berit Seiffert for performing single-particle-ICPMS analyses, Philipp Muller for supervising electron microscopy, and Elke Schumacher for performing UVVis analyses.

A flexible Pt/TiO2/γ-Al2O3 nanfiber paper (PTA) was successfully prepared by an electrospinning-coating-NaBH4 reduction method. The catalytic performance for formaldehyde (HCHO) oxidation over PTA with different Pt contents was investigated at room temperature. The results show that PTA exhibits higher catalytic activity and stability than Pt/γ-Al2O3. The TiO2 coating can promote the transformation of intermediate species and the desorption of CO2. The PTA1 with 1 wt% Pt shows the best catalytic activity and good stability. In the view of activity and cost, 0.5 wt% Pt is the optimal Pt content. The TiO2 coating not only plays an important role in improving the activity and stability of PTA, but also acts as a protective shell of γ-Al2O3 fiber, which greatly reduces the risk of alkali etching during preparation and maintains the good flexibility of PTA. The dioxymethylene (DOM), formate/carbonate species, CO are the intermediate species in HCHO oxidation over PTA. In addition, PTA exhibits good filtration performance for fine particles as well as good fluid permeability. Because of the high efficiency and flexibility of PTA composite catalytic material for HCHO oxidation with good filtration performance for fine particles, it will be a promising candidate in air purification.

The authors of the title paper (J Photochem & Photobio A:Chem 393 (2020) 112413) claim to have synthesized a toluidine tartrate (TT) crystal and examined its nonlinear optical (NLO) behavior by experimental and theoretical studies. In this critique, it is shown that the so-called TT crystal is a surface degraded material and the experimental and theoretical data contradict literature reports on the 1:1 salt of p-toluidine and l -tartaric acid.

Two-dimensional (2D) materials represent an emerging technology for transistor electronics in view of their attractive electrical and mechanical properties. This work investigates molybdenum disulfide (MoS2) based field-effect transistors (FETs) fabricated on paper substrate for designing both digital and analog circuits, such as inverter, current mirror, and Physical Unclonable Function (PUF) bitcell. Electrical measurements of fabricated devices are exploited to setup a look-up-table (LUT)-based Verilog-A model to be integrated in a commercial circuit simulator. Obtained results prove the potential of paper-based MoS2 FETs as building blocks of next-generation integrated circuits for a wide range of practical applications.

Herein, a novel paper-based chemiluminescence (CL) assay is reported using a smartphone readout for on-site and reliable analytical applications. The CL system was based on the high-performance improving effect of cobalt-imidazole metal-organic framework (CoMOF) on luminol-hydrogen peroxide (H2O2) CL emission. The CoMOF was grown on paper and used as a support for the CL reaction, which led to an intense CL emission and good reproducibility. More importantly, the stability of luminol, as the CL reagent, was greatly improved in the presence of CoMOF. This high stability, along with the high-yield CL emission, makes the device highly suitable for commercialization. Furthermore, using a smartphone as the detector for the developed device made the process easier and more accessible for public usage. In this work, the new paper-based CL smartphone device was used for the detection of the total phenolic content of food samples. Phenolic compounds (PC) are hydroxyl radical scavengers that can effectively quench the CL emission of the luminol–H2O2–CoMOF system. After optimizing the reaction conditions, the system could detect PC at the μg mL−1 level. Detection limits of 0.12, 0.28, 0.46, 0.85, and 1.23 μg mL−1 were obtained for gallic acid, quercetin, catechin, kaempferol, and caffeic acid, respectively. This work is the first report on the practical application of smartphone CL assays for the estimation of PC. The proposed assay is an easy-to-use, low-cost, portable, and suitable assay for on-site screening purposes.

In this study, eco-friendly and disposable paper-based membraneless microfluidic enzymatic fuel cells (EFCs) were developed without any mediators to reduce the toxicity and cost of EFCs. Glucose oxidase and laccase were immobilized on multi-walled carbon nanotube electrodes to catalyze the redox reaction of glucose and oxygen. Micromachining techniques well-suited for mass production were used to precisely fabricate micro-scale Y-shaped and cross-shaped EFCs. Experimental measurements showed that the concentration of glucose in the fuel solution affects the cell performance, which occurs because the flow speed of the fuel stream decreases as the concentration of glucose increases. The highest performance of power density (104.2 ± 3.35 μW cm−2) and current density (615.6 ± 3.14 μA cm−2) were obtained with the Y-shaped channel configuration at a glucose concentration of 100 mM. This performance is the best of all paper-based single EFCs reported to date. The new paper-based co-laminar flow mediatorless EFC exhibits strong potential to power miniaturized and portable on-site diagnostic devices.

Due to the rapid industrialization, heavy metals contamination in the aquatic environment has become more serious. Thus, it is urgent to develop enhanced removal technology for heavy metals. Graphene oxide (GO) based composite paper-like materials have been widely applied for adsorption of heavy metals from wastewater. Herein, we fabricated for the first time an advanced, highly-ordered and homogenous PVC/PPD/GO paper-like material using a resin-infiltration technique. This process is complimentary to layer-by-layer assembly, where the assembling components are required to interact strongly (e.g., via hydrogen bonding or electrostatic attraction). The results showed that the composite papers could achieve high removal efficiency of the heavy metals from water. The amount of Pb(II) adsorbed at equilibrium as achieved by GO, PVC/GO-0.05, PVC/GO-0.08, PVC/PPD/GO-0.05 and PVC/PPD/GO-0.08 buckypapers were 17.61, 22.17, 25.41, 33.57 and 44.80 mg g−1, respectively. In addition, the effects of experimental factors (e.g. GO content, ionic strength of heavy metal ions, temperature and solution pH) on heavy metal adsorption were discussed. Furthermore, the as-prepared PVC/PPD/GO-0.08 composite papers exhibited superior stability and could be recycled more than 900 h based on their 15 regeneration cycles. The improved heavy metal removal efficiency was attributed to the enhanced morphology and the formation of micro- and nano-channels created by the entangled PPD/GO. The findings indicated that the PVC/PPD/GO composite buckypapers could be used as promising materials for the adsorption of heavy metals from wastewater.

CaV6O16·3H2O three-dimensional (3D) tubular structure has been constructed by a simple hydrothermal method without using any surfactants or additives. The tubular structure is composed of ultralong CaV6O16·3H2O nanobelts with good tailorability. By simply cutting and drying the 3D tubular structure, a CaV6O16·3H2O paper has been successfully prepared. Electrochemical performance of the CaV6O16·3H2O paper as the self-standing cathode for lithium-ion batteries (LIBs) was investigated for the first time. It delivers an initial discharge capacity of 463.9 mAh g−1 at 50 mA g−1 and maintains at 162.3 mAh g−1 after 50 cycles. This work provides the possibility for designing high-performance, long service life and lightweight LIBs for implantable medical devices.

Rational design of photoelectrode architectures is deemed as an effective solution to enhance efficiency of photoelectrochemical water splitting for conquering increasingly prominent environmental problems. Herein, a programmable flexible photoanode with built-in tandem Z-scheme configuration fabricated by in-situ growth of MoSe2-CdS-ZnO array with ultrathin nanosheet-interlaced-nanorod structure on the Au paper electrode, is firstly reported. By taking advantages of the interwoven nanonetwork structure, high conductivity as well as larger porosity of the as-fabricated Au paper electrode, a stable light-harvesting paper chip with fast transfer/separate mediators of the charge/carriers is thus integrated. By virtue of double internal electric fields (IEFs) and photothermal effect, the developed MoSe2-CdS-ZnO photoanode exhibits incident-photon-to-current efficiency of 52 % under 460 nm of light irradiation, and the current density reaches 2.4 mA cm−2 at 0.3 V versus normal hydrogen electrode, which is comparable with respect to current state-of-the-art “type-II-scheme”, “surface-scheme”, and cocatalyst-free photocatalysts (0.03–2.4 mA cm−2). Consequently, the paper-based photoanode achieves admirable photoelectrocatalytic hydrogen generation property (39.7 μmol cm−2 h-1). The synergistic effect of tailorable tandem Z-scheme configuration with double IEFs and delineating of 3D cross-linked network structure of the proposed photoanode in this work may open an avenue for constructing high-performance photoelectrochemical water splitting devices.

We preliminarily examined whether it is possible to visualize synthetic materials applied to the surface of a base material by using near-infrared hyperspectral imaging at wavelengths of 1.0–2.35 µm. We focused on the applicability of this method for visualizing adhesives and varnishes, assessing the effect of underlying colorants on measurements, and selecting the optimal method for data analysis. Experimental samples were adhesive on a painted ceramic plate and varnish on printed paper. We performed correlation analysis, partial least squares regression analysis, linear discriminant analysis, decision tree, KNN and principal component scores 1 and 2 to evaluate the measurement data. The conventional method (visible/near-infrared spectroscopic/fluorescence photographs at wavelengths of 400–1000 nm.) could not visualize the adhesive on the painted ceramic plate or the varnish on the printed paper, whereas the new method could do so. Therefore, this method has the potential to be useful for inspecting the distribution of synthetic materials on the surface of a base material.

After ban on single-use plastics, completely bio-based coating on paper is in great demand to replace the plastics liner and other organic-inorganic hybrid coating. To resolve the issues like moisture, hydrophilicty and repulpability after use, a green, sustainable and hydrophobic bio-coating material for paper substrate has been developed. In this work, silanized castor oil (SCO) and silanized methyl ricinoleate (SMR) bio-resins are synthesized by structural modifications of epoxidized castor oil through transesterification and silanization process, Subsequently, the silylated bio-resins are hydrolysed and subjected to crosslinking with cellulosic paper substrate through condensation process. The coated papers showed hydrophobicity with water contact angle (WCA) up to 97° and strongly moisture resistant (moisture content of 2–3%) nature. Scanning electron microscopy analysis with energy dispersive X-ray spectra confirms the uniform coating of SMR resin with better texture and higher degree of silane grafting. The water vapor transmission rate (WVTR) decreased by 77.5% after coating because of blockage of pores and strong bonding with the cellulosic fibers. Further the coated papers showed adequate thermal stability and better tensile strength for commercial packaging. These coatings are removed by exposing to strong alkali solution at 90 °C and the recyclability potential of the paper is confirmed for reuse. These renewable resourced and eco-friendly coating materials are found to be suitable alternative for paper packaging and other coating applications with circular economy approach.

Paper waste generation has been rising in the past decades, with a large amount being landfilled. These paper wastes can be great energy sources after thermal treatment since they are considered carbon neutral. These wastes contain mainly cellulose, hemicellulose, lignin, and some minerals. The thermal decomposition of cellulose, hemicellulose, and lignin have been extensively studied, however, the knowledge of thermal degradation of paper wastes at lower temperatures, which are more practical for industrial applications are still lacking. In this study, paper wastes have been characterized and thermogravimetric analyses were performed from 200°C to 400°C and the char produced were analyzed by nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. Two kinetic approaches were taken while developing the kinetic model of paper waste thermal degradation: (i) reconstructing the TGA results of paper waste thermal degradation by an additive law of the degradation of cellulose, hemicellulose and lignin; (ii) considering paper waste as one material and develop a multi-step consecutive reaction mechanism that focuses on solid products at different temperatures. It was observed that there are potential interactions between cellulose, hemicellulose and lignin during paper waste degradation. Therefore, the second approach was concluded to be more plausible, and one set of kinetic parameters were determined according to the experimental results at different temperatures. These results provided insights into the degradation kinetic mechanism and solid product distribution of the paper waste. It was found that the first reaction was due to dehydration of cellulose and the 6th and 7th reaction can be attributed to the thermal degradation of lignin. The NMR and FTIR results also validated that the cellulose started degrading at lower temperatures, and lignin degradation became more pronounced at higher temperatures.

Integrating graphene with other kinds of biochemical molecules is an effective way to improve the properties of graphene film. Proteins are promising candidates for graphene hybridization. We create an effective method to prepare multifunctional graphene hybrid film by incorporation of antibacterial protamine. Protamine could be stably adsorbed on the surface of GO as both a reductant and an antibiotic to realize antimicrobial protamine/RGO conjugates. The presence of decorated protein layers makes it possible to adjust the physical performance of the composite. The obtained hybrid papers show improved hydrophilic property of reduced GO paper. These freestanding papers have a reversible humidity response shape-memory effect and great antibacterial property. The facile strategy possesses a promising way to develop multifunctional antibacterial materials.

Cellulose-based materials have attracted tremendous interest recently due to their fascinating merits of renewability, biodegradability, and low cost, holding great promise in electromagnetic protection, clean energy harvesting, and thermal management. However, the simple and effective integration of multiple functions into single cellulose material remains a challenge. Herein, we report the fabrication of a multifunctional and superhydrophobic cellulose composite paper (CCP) via coated MXene modified by in-situ polymerized polypyrrole and PDMS/candle soot on the opposite surface of the paper. CCP exhibits high-performance electromagnetic interference shielding effectiveness (~40 dB) while maintaining high electrical conductivity (1467 S/m). Moreover, the superhydrophobic surface of CCP can be used as the hydraulic triboelectric nanogenerator (H-TENG) to harvest water energy due to the liquid–solid contact triboelectrification and electrostatic induction. The hydraulic triboelectric energy can be captured and released when water droplets drop from a height of 2 cm and roll at a tilt angle of 20°, the output current can reach a peak of 0.8 nA. Furthermore, the surface saturation temperature of CCP can reach 140 °C with a low applied voltage of 6 V enabled by the Joule effect. Thus, CCP holds great potentials in applications of integrated smart electronics, clean energy harvesting, and thermal management.

Graphitic layer of carbon has been deposited on the surface of cellulose paper by simple pencil drawing approach. The edges of exfoliated multilayer graphene sheets formed during pencil drawing on the rough paper surface causes the enhancement of electrochemical capacitance. One step chemical polymerization technique has been adopted to fabricate polyaniline nanofibers on hydrophobic pencil drawn graphitic layer on the cellulose paper. These polyaniline coated pencil drawn paper electrodes were used to fabricate all-solid-state symmetric supercpapcitors with superior performance in comparison to similar pencil drawn paper electrodes without polyaniline. All-solid-state symmetric supercapacitor with paper based multilayer graphene-polyaniline nanofiber electrodes exhibits specific capacitance of 28.37 F g−1, areal capacitance of 93.64 mF cm−2, energy density of 8.32 µW h cm−2, and power density of 39.97 µW cm−2. It also shows excellent cyclic stability with initial increment to a maximum value and then decrease to 91.5 % of the maximum value after 5000 cycles. It is interesting to note that it retains 134.28 % of initial areal capacitance after 5000 cycles.

Developing 3D printable waste paper based biocomposites is a potentially greener alternative to traditional waste paper recycling methods. In this paper, waste office paper (WOP) filled polylactide acid (PLA) biocomposites were prepared as filaments for Fused Filament Fabrication (FFF). The morphology, rheology, thermal properties, and physical properties of PLA-WOP composites were investigated. Results revealed that the addition of WOP improved the composites’ melt flow abilities. The Tg and Tm of composites remained similar to the neat PLA. However, tensile strengths of the prints decreased with the increase of WOP content, which could be attributed to the heterogeneous dispersion and aggregation caused by the abundance of WOP in the system. When 5% WOP was used, the elongation at break increased in comparison with pure PLA specimens. Nonetheless, when the WOP content was increased to 15%, the elongation at break decreased. To improve the mechanical properties of the prints, a silane coupling agent (γ-methacryloxypropyltrimethoxylsilane, KH570) was used to modify WOP granules. The mechanical properties were clearly enhanced post KH570 treatment. Furthermore, FTIR analyses demonstrated that the hydrogen bonding improved interfacial adhesion between WOP fillers and the PLA matrix. Thermal decomposition showed that the PLA-WOP composites had virtually no degradation below 260 °C, indicating that the composite filaments are safe for indoor 3D printing.