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Cellulose-based materials have recently drawn much interest due to their sustainability, biodegradability, biocompatibility, and low cost. In this present work, cellulose fiber paper (CFP) was fabricated from sugarcane leaves and used as a friction material for a triboelectric nanogenerator (TENG). Fe3O4 was incorporated to CFP triboelectric material to increase the dielectric constant of CFP for boosting power generation of TENG. The Fe3O4 filled CFP was synthesized using a facile one-pot co-precipitation technique. The effect of Fe3O4 content in CFP on dielectric property and TENG performance was investigated and optimized. The CFP filled with Fe3O4 nanoparticles exhibited the improved dielectric constant and possessed a superior TENG performance than pristine CF. The highest power density of 1.9 W/m2 was achieved, which was able to charge commercial capacitors serving as a power source for small electronic devices.

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.

A great paradigm for foremost food packaging is to use renewable and biodegradable lignocellulose−based materials instead of plastic. Novel packages were successfully prepared from the cellulose paper by coating a mixture of polylactic acid (PLA) with cinnamaldehyde (CIN) as a barrier screen and nano silica−modified stearic acid (SA/SiO2) as a superhydrophobic layer. As comprehensively investigated by various tests, results showed that the as−prepared packages possessed excellent thermal stability attributed to inorganic SiO2 incorporation. The excellent film−forming characteristics of PLA improved the tensile strength of the manufactured papers (104.3 MPa) as compared to the original cellulose papers (70.50 MPa), enhanced by 47.94%. Benefiting from the rough nanostructure which was surface−modified by low surface energy SA, the contact angle of the composite papers attained 156.3°, owning superhydrophobic performance for various liquids. Moreover, the composite papers showed excellent gas, moisture, and oil bacteria barrier property as a result of the reinforcement by the functional coatings. The Cobb300s and WVP of the composite papers were reduced by 100% and 88.56%, respectively, and their antibacterial efficiency was about 100%. As the novel composite papers have remarkable thermal stability, tensile strength, and barrier property, they can be exploited as a potential candidate for eco−friendly, renewable, and biodegradable cellulose paper−based composites for the substitute of petroleum−derived packages.

The life expectancy of power transformers is primarily determined by the integrity of the insulating oil and cellulose paper between the conductor turns, phases and phase to earth. During the course of their in-service lifetime, the solid insulating system of windings is contingent on long-standing ageing and decomposition. The decomposition of the cellulose paper insulation is strikingly grievous, as it reduces the tensile strength of the cellulose paper and can trigger premature failure. The latter can trigger premature failure, and to realize at which point during the operational life this may occur is a daunting task. Various methods of estimating the DP have been proposed in the literature; however, these methods yield different results, making it difficult to accurately estimate a reliable DP. In this work, a novel approach based on the Feedforward Backpropagation Artificial Neural Network has been proposed to predict the amount of DP in transformer cellulose insulation. Presently, no ANN model has been proposed to predict the remaining DP using 2FAL concentration. A databank comprising 100 data sets—70 for training and 30 for testing—is used to develop the proposed ANN using 2-furaldehyde (2FAL) as an input and DP as an output. The proposed model yields a correlation coefficient of 0.958 for training, 0.915 for validation, 0.996 for testing and an overall correlation of 0.958 for the model.

The radical proliferation of pathogenic bacteria and their infections causes significant issues for human health and the environment. Today, biopolymers are used to produce different nanoparticles. In the present investigation, the fabricated chitosan/agar-silver nanoparticles (Cht/Ar-AgNPs)-coated papers were tested for antibacterial applications. Agar was used as a reducing agent for the synthesis of AgNPs. Synthesized Ar-AgNPs were examined through optical, phase crystallinity and topological analysis. Cht and Ar-AgNPs solution was mixed with various ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 by weight. In addition to that, the conformity of Cht/Ar-AgNPs-coated papers was characterized by structural, spectral, and morphological analysis. However, Cht/Ar-AgNPs-coated papers were subjected to antibacterial properties. The ratio of (6:4) Cht/Ar-AgNPs-coated paper showed excellent antibacterial agent, and it can be used as extending the food product shelf life.

Generally, impregnation of solid insulation is performed to increase the dielectric strength and reduce the dielectric losses of solid insulants. This increase in dielectric strength depends on the oil’s diffusion and dielectric properties. This paper investigates the diffusion behavior of mineral oil and ester fluids (synthetic, natural, and mixed) to understand the influence of oil diffusion on paper breakdown voltage. To better understand this phenomenal influence, cellulose insulation paper of different thicknesses has been considered. Wetting characteristics of various oil-paper insulation systems were investigated with and without thermal stressing. Thermal aging was carried out as per modified ASTM D1934 at 110 °C, 140 °C, 160 °C, and 185 °C respectively for 2 weeks. The wetting characteristics and influence of different oils on paper breakdown voltage were explicitly reported. It is inferred that paper wetting characteristics are attributable to the type of oil, the thickness of paper, and the aging factor of oil-paper insulation. Importantly, the increase in paper dielectric strength and diffusion behavior for ester fluids is found to be superior to that of the mineral insulating oils.

Abstract It has been a research goal to develop macroscopic materials with an optimized surface structure to affix silver nanoparticles which could contaminate water and maximize their practical functions. Cellulose paper is a versatile biomass material valued for its abundance, low cost, biocompatibility, and natural composition. Until now, its potential application in water purification has not been adequately explored. In this study, gallic acid-modified silver nanoparticles (GA@AgNPs) were loaded onto commercial cellulose filter paper using a simple lipoic acid modification process (GA@AgNPs-LA-CP). Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to characterize the GA@AgNPs-LA-CP. The catalytic activity of the GA@AgNPs-LA-CP was evaluated by the reduction reaction of methylene blue (MB), Rhodamine B (RhB), and 4-nitrophenol (4-NP) with sodium borohydride (NaBH4). The GA@AgNPs-LA-CP exhibited excellent catalytic activity toward MB, RhB, and 4-NP, taking advantage of its high specific surface area generated by the cellulose fiber network structure. Interestingly, due to the electrostatic interactions between the cationic dyes and the GA@AgNPs, the as-prepared catalytic composite material serves as a better catalyst for MB and RhB, suggesting dual applications of the composite materials for organic wastewater treatment and the removal of harmful dyes. This implies that the immobilization of AgNPs on cellulose papers is an effective method and can be applied to efficient wastewater treatment applications. Graphical abstract

The paper presents the results of copper electroless metallization of cellulose paper with the use of a polydopamine coating and silver catalyst. The polydopamine coating was deposited via a simple dip method using a dopamine hydrochloride solution in 10 mM TRIS-HCl buffer with a pH of 8.5. The research showed that as a result of this process, cellulose fibers were covered with a homogeneous layer of polydopamine. The unique properties of the polydopamine coating allowed the reduction of silver ions from silver nitrate solution and the deposition of silver atoms on the paper surface. Deposited silver served as a catalyst in the autocatalytic electroless copper-plating process. The copper layer covered the entire surface of the paper sheet after 5 min of metallization, favorably affecting the electrical properties of this material by lowering the surface resistivity. The deposited copper layer was further characterized by good adhesive strength and high susceptibility to deformation.

The development of a solid substrate for the support and stabilization of zero-valent metal nanoparticles (NPs) is the heart of the catalyst system. In the current embodiment, we have prepared solid support comprise of alginate-coated cellulose filter paper (Alg/FP) for the synthesis and stabilization of Co nanoparticles (NPs) named as Alg/FP@Co NPs. Furthermore, Alginate polymer was blended with 1 and 2 weight percent of CoNi NPs to make Alg-CoNi1/FP and Alg-CoNi2/FP, respectively. All these stabilizing matrixes were used as dip-catalyst for the degradation of azo dyes and reduction of 4-nitrophenol (4NP). The effect of initial dye concentration, amount of NaBH4, and catalyst dosage was assessed for the degradation of Congo red (CR) dye by using Alg-CoNi2/FP@Co NPs. Results indicated that the highest kapp value (3.63 × 10−1 min−1) was exhibited by Alg-CoNi2/FP@Co NPs and lowest by Alg/FP@Co NPs against the discoloration of CR dye. Furthermore, it was concluded that Alg-CoNi2/FP@Co NPs exhibited strong catalyst activity against CR, and methyl orange dye (MO) degradation as well as 4NP reduction. Antibacterial activity of the prepared composites was also investigated and the highest l activity was shown by Alg-CoNi2/FP@Co NPs, which inhibit 2.5 cm zone of bacteria compared to other catalysts.

In this work, the design and development of a microfluidic paper-based device (μPAD) for the quantification of total phenolic compounds (TPC) in wines is described. The developed μPAD was based upon the vertical flow concept and the colour reaction used was the known Folin-Ciocalteu reaction using gallic acid as reference phenolic compound. After studying operational parameters, namely type of paper, reagents and sample volume, a dynamic range of 5–50 mg L−1 was obtained with a limit of detection of 1.2 mg L−1. The described device proved to have good precision (relative standard deviation < 5%) and no significant interferences were observed from known compounds present in wines. Furthermore, the stability of the colour product and of the device itself were assessed; the μPAD was stable for 30 days (in the dark at room temperature) and it could be scanned up to 8 h after sample introduction. The developed μPAD pose as a simple method for TPC quantification and was successfully applied to several wine samples including sparkling and table wines with two different approaches: i) using gallic acid as reference compound with standard addition; and ii) using taniraisin with external calibration. The accuracy of the proposed μPAD method was assessed by comparison with the reference spectrophotometric method according to the International Organisation of Vine and Wine (OIV) recommendations.

Novel high-performance biosensing devices, based on a microporous cellulose matrix, have been of great interest due to their high sensitivity, low cost, and simple operation. Herein, we report on the design and testing of portable paper-based immunostrips (IMS) for in-field blood typing in emergencies requiring blood transfusion. Cellulose fibrils of a paper membrane were functionalized with antibodies via supramolecular interactions. The formation of hydrogen bonds between IgM pentamer and cellulose fibers was corroborated using quantum mechanical calculations with a model cellulose chain and a representative amino acid sequence. In the proposed immunostrips, paper with a pore size of 3 µm dia. was used to enable functionalization of its channels with antibody molecules while blocking the red blood cells (RBC) from channel entering. Under the optimized test conditions, all blood types of AB0 and Rh system could be determined by naked eye examination, requiring only a small blood sample (3.5 µL). The durability of IgM immunostrips against storing has been tested. A new method of statistical evaluation of digitized blood agglutination images, compatible with a clinical five-level system, has been proposed. Critical parameters of the agglutination process have been established to enable future development of automatic blood typing with machine vision and digital data processing.

Cellulose paper has been functionalized by nanoparticles such as Ag nanoparticles, TiO2, and BaTiO3 for versatile applications including supercapacitor, sensors, photoactivity, and packaging. Herein, zinc oxide (ZnO) nanosheet-modified paper (ZnO@paper) with excellent antibacterial properties was fabricated via a mild ZnCl2-urea eutectic solvent. In this proposed method, cellulose fibers as the raw material for ZnO@paper were treated by an aqueous solvent of ZnCl2-urea; the crystalline region was destroyed and [ZnCl]+-based cations were adsorbed on the surface of cellulose fibers, facilitating more ZnO growth on ZnO@paper. A flexible paper-based triboelectric nanogenerator (P-TENG) was made of ZnO@paper paired with a PTFE film. The P-TENG presents high triboelectric output performance and antibacterial activity. For instance, the output voltage and current of the P-TENG were 77 V and 0.17 μA, respectively. ZnO@paper showed excellent antibacterial activity against E. coli and S. aureus, suggesting that a P-TENG can restrain and kill the bacteria during the working process. The results also indicated that ZnO could improve the surface roughness of cellulose paper, enhancing the output performance of a flexible P-TENG. In addition, the potential application of a P-TENG-based pressure sensor for determining human motion information was also reported. This study not only produced a high-performance P-TENG for fabricating green and sustainable electronics, but also provides an effective and novel method for ZnO@paper preparation.

Cellulose paper has been functionalized by nanoparticles such as Ag nanoparticles, TiO2, and BaTiO3 for versatile applications including supercapacitor, sensors, photoactivity, and packaging. Herein, zinc oxide (ZnO) nanosheet-modified paper (ZnO@paper) with excellent antibacterial properties was fabricated via a mild ZnCl2-urea eutectic solvent. In this proposed method, cellulose fibers as the raw material for ZnO@paper were treated by an aqueous solvent of ZnCl2-urea, the crystalline region was destroyed and [ZnCl]+-based cations were adsorbed on the surface of cellulose fibers, facilitating more ZnO growth on ZnO@paper. A flexible paper-based triboelectric nanogenerator (P-TENG) was made of ZnO@paper paired with a PTFE film. The P-TENG presents high triboelectric output performance and antibacterial activity. For instance, the output voltage and current of the P-TENG were 77 V and 0.17 μA, respectively. ZnO@paper showed excellent antibacterial activity against E. coli and S. aureus, suggesting that a P-TENG can restrain and kill the bacteria during the working process. The results also indicated that ZnO could improve the surface roughness of cellulose paper, enhancing the output performance of a flexible P-TENG. In addition, the potential application of a P-TENG-based pressure sensor for determining human motion information was also reported. This study not only produced a high-performance P-TENG for fabricating green and sustainable electronics, but also provides an effective and novel method for ZnO@paper preparation.

International audience; Despite its millennial age, cellulose paper remains the preferred material for domestic and professional printings, covering applications from simple office paperwork to fiducial solutions such as bills, passports, and head letters. The creation of robust photochromic patterns on cellulose papers for anti-counterfeiting applications is an important and still partially unaddressed challenge. In this contribution, we report the covalent printing of dibenzothienylethenes as photochromic compounds through a spatially-controlled light mediated thiol-X ligations. Photophysical and theoretical studies provide evidences for a reversible photochromism behavior, not affected significantly by the polar environment of the cellulose matrix, and demonstrates a high fatigue resistance over 18 successive write-erase cycles. The strong coloration-discoloration switch can be easily followed by a direct nakedeye readout.

Paper is a popular platform material in all areas of sensor research due to its porosity, large surface area, and biodegradability, to name but a few. Many paper-based nanocomposites have been reported in the last decade as novel substrates for surface-enhanced Raman spectroscopy (SERS). However, there are still limiting factors, like the low density of hot spots or loss of wettability. Herein, we designed a process to fabricate a silver–chitosan nanocomposite layer on paper celluloses by a layer-by-layer method and pH-triggered chitosan assembly. Under microscopic observation, the resulting material showed a nanoporous structure, and silver nanoparticles were anchored evenly over the nanocomposite layer. In SERS measurement, the detection limit of 4-aminothiophenol was 5.13 ppb. Furthermore, its mechanical property and a strategy toward further biosensing approaches were investigated.

Herein, a fully paper‐based all‐solid‐state supercapacitor with functionalized cellulose paper as electrodes, carboxymethyl cellulose gel as solid electrolyte and cellulose paper as separator was fabricated. The electrode was fabricated by a conventional papermaking process with silver‐modified fibers and graphene oxide (GO)‐modified fibers followed by reduction of GO. The Ag‐modified fibers and GO‐modified fibers were obtained by in situ growth of Ag nanoparticles and self‐assembly of GO sheets on cellulose fibers, respectively. Ag‐modified fibers act as a flexible current collector with rich three‐dimensional interconnected electron transport pathways to make the reduced GO‐modified fibers as electrode materials to achieve high conductivity (1.93 Ω sq−1) and high‐rate capability. Simple drying can reduce 40% weight of the supercapacitor to facilitate transportation and storage, and its capacitance efficiency can be recovered by wetting when needed. This work opens up a new way of developing cheap, green and high performance full‐paper flexible electronics by conventional papermaking process.

For the first time, a novel NiFe2O4/paper-based magnetoelastic (ME) biosensor was developed for rapid, sensitive, and portable detection of human serum albumin (HSA). Due to the uniquely magnetoelastic effect of NiFe2O4 nanoparticles and the excellent mechanical properties of the paper, the paper-based ME biosensor transforms the surface stress signal induced by the specific binding of HSA and antibody modified on the paper into the electromagnetic signal. The accumulated binding complex generates a compressive stress on the biosensor surface, resulting in a decrease in the biosensor&rsquo, s static magnetic permeability, which correlates to the HSA concentrations. To improve the sensitivity of the biosensor, the concentration of NiFe2O4 nanofluid and the impregnated numbers of the NiFe2O4 nanofluid-impregnated papers were optimized. The experimental results demonstrated that the biosensor exhibited a linear response to HSA concentrations ranging from 10 &mu, g∙mL&minus, 1 to 200 &mu, 1, with a detection limit of 0.43 &mu, 1, which is significantly lower than the minimal diagnosis limit of microalbuminuria. The NiFe2O4/paper-based ME biosensor is easy to fabricate, and allows the rapid, highly-sensitive, and selective detection of HSA, providing a valuable analytical device for early monitoring and clinical diagnosis of microalbuminuria and nephropathy. This study shows the successful integration of the paper-based biosensor and the ME sensing analytical method will be a highly-sensitive, easy-to-use, disposable, and portable alternative for point-of-care monitoring.

For the first time, a novel NiFe2O4/paper-based magnetoelastic (ME) biosensor was developed for rapid, sensitive, and portable detection of human serum albumin (HSA). Due to the uniquely magnetoelastic effect of NiFe2O4 nanoparticles and the excellent mechanical properties of the paper, the paper-based ME biosensor transforms the surface stress signal induced by the specific binding of HSA and antibody modified on the paper into the electromagnetic signal. The accumulated binding complex generates a compressive stress on the biosensor surface, resulting in a decrease in the biosensor’s static magnetic permeability, which correlates to the HSA concentrations. To improve the sensitivity of the biosensor, the concentration of NiFe2O4 nanofluid and the impregnated numbers of the NiFe2O4 nanofluid-impregnated papers were optimized. The experimental results demonstrated that the biosensor exhibited a linear response to HSA concentrations ranging from 10 μg∙mL−1 to 200 μg∙mL−1, with a detection limit of 0.43 μg∙mL−1, which is significantly lower than the minimal diagnosis limit of microalbuminuria. The NiFe2O4/paper-based ME biosensor is easy to fabricate, and allows the rapid, highly-sensitive, and selective detection of HSA, providing a valuable analytical device for early monitoring and clinical diagnosis of microalbuminuria and nephropathy. This study shows the successful integration of the paper-based biosensor and the ME sensing analytical method will be a highly-sensitive, easy-to-use, disposable, and portable alternative for point-of-care monitoring.

Natural oils with their price and environment-friendly behaviour are more used these days like insulation fluids in transformers. There are often based on eg. rapeseed, soy, sunflower etc. oils. Compatibility between new materials used in transformers needs to be further discussed. Few papers already describe the behaviour of insulating papers and materials like gaskets, varnishes or core steel with soy or corn oil. This paper describes the compatibility of cable ties and rubber-based gasket and part of transformer bushing. These materials were placed into insulation oils, in our case rapeseed oil-based and for comparison to mineral oil Nynas Lyra, and thermally aged in the oven for 2000 hours at 120 °C and 1000 hours at 140 °C. All polymers and oils were analysed before and after ageing. Properties as weight and dimensions change, hardness by Shore and permittivity, resistivity, dissipation factor, the viscosity of oils are discussed.

Paper-based microfluidic devices based on electrowetting principle, more specifically electrowetting on dielectric (EWOD), have attracted increasing attention due to their powerful liquid handling capability as compared to continuous-flow paper-based analytical devices (μPAD) that use capillary effects to control liquids. Here, we demonstrate fabrication of paper-based EWOD devices using cellulose paper as substrate and paraffin wax as dielectric hydrophobic layer by a simple pressing treatment for the cellulose paper and melting or spray-coating of paraffin wax. We optimized the key fabrication parameters according to the surface morphology and hydrophobicity of the obtained wax film, including the pressing pressure, thermal annealing temperature and amount of paraffin wax. Moreover, the EWOD devices fabricated by the spray-coating method demonstrate larger contact angle changes but with smaller contact angle hysteresis under DC electric field when compared with the devices fabricated by the melting method. Our study opens up potential fabrication of hybrid paper-based microfluidic device combining advantages of continuous-flow and electrowetting using cellulose paper and paraffin wax.

Organic solvents with high purity are essential in various fields such as optical, electronic, pharmaceutical, and chemical areas to prevent low-quality products or undesired side-products. Constructing methods to remove impurities such as water residue in organic solvents has been a significant challenge. Within this article, we report for the first time a new method for the preparation of hydrophobic and oleophilic filter paper (named OCFP), based on thermally induced silane dehydrocoupling between cellulose-based filter paper and octadecylsilane. We comprehensively characterized OCFP using various characterization techniques (FTIR, XPS, XRD, and EDS). OCFP showed super-hydrophobic and oleophilic properties as well as remarkable water separation and removal efficiency (&gt, 93%) in various organic solvents with sustained reusability. In addition, the analytical results both before and after filtration of an NMR solvent using OCFP indicated that OCFP has an excellent solvent drying efficiency. This work presents a new strategy for the development of super-hydrophobic cellulose-based filter paper, which has great potential for solvent drying and water separation.

We have previously reported that crystalline samples of 1-acetylaminopyrene (AAPy), 1-octanoylaminopyrene (OAPy), and 1-stearoylaminopyrene (SAPy) exhibited mechanochromic luminescence. In the present study, we have found that these 1-alkanoylaminopyrenes adsorbed onto cellulose papers also exhibited mechanochromic luminescence; however, their behaviors were essentially different from those observed for their crystalline samples. In addition, these cellulose papers were found to exhibit reversible emission color change upon alternate exposure to ethanol and water vapors. It was suggested that 1-alkanoylaminopyrene molecules were dispersed in the paper without aggregation or crystallization and that intermolecular distance of 1-alkanoylaminopyrenes in the paper was reduced by either mechanical stress or exposure to ethanol vapor, resulting in increasing the sites where excimers could be formed and/or in enhancing the efficiencies of energy migration to reach the excimer sites.

With the aim of exploring an alternative method of nano-doping in cellulose paper and improving flashover strength of oil-impregnated paper, radio frequency (RF) magnetron sputtering method is introduced into the structural modification of insulating paper for converter transformers. In this experiment, insulating paper was treated with ZnO sputtering for 0, 7.5, 15 and 30 min, respectively. The surface morphology of dry paper was observed with a scanning electron microscope. The bonding mode of sputtered ZnO particles with cellulose matrix was investigated via attenuated total reflection infrared (ATR-IR) spectroscopy and mechanical property of the sputtered samples were studied. Surface and volume conductivities of the oil-impregnated sputtered paper were measured. Moreover, the charge dissipation characteristics of sputtered insulating paper was investigated by means of surface potential decay. In addition, trap distribution and carrier mobility of specimen were further obtained. Finally, the DC flashover strength were tested. The results showed that ZnO magnetron sputtering had a distinct influence on the structure of the insulating paper, resulting in the formation of hydrogen bond and chemical bond and an increase of the surface and volume conductivities. ZnO sputtering was found to decrease the initial potential and accelerate charge decay. Moreover, appropriate sputtering enhanced the surface flashover strength.

We report an entirely new class of printed electrical gas sensors that are produced at near “zero cost”. This technology exploits the intrinsic hygroscopic properties of cellulose fibers within paper; although it feels and looks dry, paper contains substantial amount of moisture, adsorbed from the environment, enabling the use of wet chemical methods for sensing without manually adding water to the substrate. The sensors exhibit high sensitivity to water-soluble gases (e.g., lower limit of detection for NH3 < 200 parts-per-billion) with a fast and reversible response. The sensors show comparable or better performance (especially at high relative humidity) than most commercial ammonia sensors at a fraction of their price (

In this work, zinc oxide (ZnO) and titanium dioxide (TiO2) nanostructures were grown on different cellulose paper substrates, namely Whatman, office, and commercial hospital papers, using a hydrothermal method assisted by microwave irradiation. Pure ZnO and TiO2 nanostructures were synthesized, however the growth of TiO2 above the ZnO was also investigated to produce a uniform heterostructure. Continuous ZnO nanorod arrays were grown on Whatman and hospital papers, however on office paper, it could be observed the formation of nanoplates originating nanoflower structures. TiO2 nanoparticles homogeneously covered all the substrates and, in some conditions, forming uniform TiO2 films. The structural characterization was carried out by SEM coupled with EDS, XRD and Raman spectroscopy. The optical characterization of all the materials was carried out. The produced materials were investigated for multifunctional applications, like photocatalyst agents, bacterial inactivators and ultraviolet (UV) sensors. To evaluate the photocatalytic activity under UV and solar radiations, rhodamine B was the model-test contaminant indicator and the best photocatalytic activity was achieved with Whatman paper. Hospital paper with TiO2 nanoparticles showed significant antibacterial properties against Staphylococcus aureus. ZnO-based UV sensors on Whatman demonstrated a responsivity of 0.61 μA W-1.

Bacterial cellulose was combined with wood cellulose papers in order to obtain biomaterials with increased barrier properties. For this purpose, different parameters were assessed: two producing bacterial strains (Komagataeibacter xylinus and Gluconacetobacter sucrofermentans), two paper supports to hold bacterial cellulose (filter paper and eucalyptus paper), two kinds of combined biomaterials (composite and bilayer) and two drying temperatures (90 °C and room temperature). Papers with increased barrier properties (100° of water contact angle, 1220 s of water drop test and air permeability

As blood tests provide information about a person’s state of health, oil analyses provide information about the condition of a transformer. Transformer oil testing has proven to be an excellent tool for early defect identification in preventive maintenance of oil-filled transformers. It has permitted extended service life by giving a measure of both oil and solid insulation condition, and by identifying the presence of incipient thermal and dielectric faults. When performed regularly, oil analysis will help the asset manager run a cost-effective maintenance program for transformers. This column addresses some recent developments in oil analysis, such as sustainable alternatives for mineral oil, an alternative marker for analysis of paper degradation, and online transformer oil monitoring.

To reduce fire hazards and expand high-value applications of lignocellulosic materials, thin films comprising graphene nanoplatelets (GnPs) and multi-wall carbon nanotubes (CNTs) pre-adsorbed with alkali lignin were deposited by a Meyer rod process. Lightweight and highly flexible papers with increased gas impermeability were obtained by coating a protective layer of carbon nanomaterials in a randomly oriented and overlapped network structure. Assessment of the thermal and flammability properties of papers containing as low as 4 wt % carbon nanomaterials exhibited self-extinguishing behavior and yielded up to 83.5% and 87.7% reduction in weight loss and burning area, respectively, compared to the blank papers. The maximum burning temperature as measured by infrared pyrometry also decreased from 834 °C to 705 °C with the presence of flame retardants. Furthermore, papers coated with composites of GnPs and CNTs pre-adsorbed with lignin showed enhanced thermal stability and superior fire resistance than samples treated with either component alone. These outstanding flame-retardant properties can be attributed to the synergistic effects between GnPs, CNTs and lignin, enhancing physical barrier characteristics, formation of char and thermal management of the material. These results provide great opportunities for the development of efficient, cost-effective and environmentally sustainable flame retardants.

We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

Transformatori se prema izvedbi dijele na uljne i suhe transformatore. U ovome radu opisani su uljni transformatori kod kojih su namoti međusobno i prema ostalim vodljivim dijelovima izolirani čvrstom izolacijom i uljem. Ulja koja se koriste kao izolacijske tekućine mogu biti esterska i mineralna ulja. Sintetsko estersko ulje je biorazgradljivo i ima veću toplinsku postojanost u usporedbi s mineralnim transformatorskim uljem, a mineralno ulje ima veću oksidacijsku stabilnost u usporedbi s esterskim uljem. Čvrsta izolacija transformatora je celulozni papir načinjen od visoko kvalitetnih pamučnih vlakana. Djelovanjem različitih čimbenika dolazi do degradacije celuloze te do oksidacije ulja pri čemu dolazi do starenja glavne izolacije uljnog transformatora i na temelju toga se provode ispitivanja pri kojima se utvrđuje starost izolacije prije nego li dođe do kvara transformatora. Ispitivanja vezana uz stanje izolacije provode se prema normama. Karakteristična ispitivanja transformatorskog ulja i papira su: kromatografska analiza plinova (DGA), fizikalno-kemijska ispitivanja ulja, ukupni sadržaj plinova u ulju, analiza sadržaja furana (HPLC), stupanj polimerizacije papira, prekidna čvrstoća papira i mjerenje sadržaja vlage u ulju i papiru. Osim karakterističnih ispitivanja transformatorskog ulja i papira, provode se i ispitivanja ulja i papira s ostalim izolacijskim materijalima, a neka od njih su: kiselost ulja, međupovršinska napetost između ulja i vode, faktor dielektričkih gubitaka i otpor ulja, nastajanje plinova iz gumenih materijala. Također, postoje metode ispitivanja izolacijskog sustava istosmjernim i izmjeničnim naponom, te mjerenjem temperature najtoplije točke namota. The transformers can be divided into oil and dry transformers. In this paper are described oil transformers in which the windings are interconnected with other conductive parts by isolation and oil. The oils used as insulating liquids can be esters and mineral oils. Synthetic ester oils are biodegradable and have higher thermal stability compared to mineral transformer oils, and mineral oil has a higher oxidative stability compared to ester oil. Solid insulation of the transformer is cellulose paper made from high quality cotton fibers. By the action of various factors cellulose degradation and oil oxidation result in the aging of the main isolation of the oil transformer, and on this basis tests are carried out to determine the age of insulation before the transformer fails. Insulation-related tests are conducted according to standards. Characteristic tests of transformer oil and paper are: dissolved gas analysis (DGA), physico-chemical analysis of oil, total oil content in oil, high-performance liquid chromatography (HPLC), degree of polymerization of paper, tensile strength of paper and measurement of moisture content in oil and paper. In addition to the typical testing of transformer oil and paper, oil and paper testing with other insulating materials are also carried out, some of which are: oil acidity, surface tension between oil and water, dielectric loss factor and oil resistance, formation of rubber gases. Also, there are methods for testing the isolation system by DC and alternating voltage and by measuring the warmest temperature of the winding point.

Water diffusion in cellulose was studied via two-phase Karger model and the propagator method. In addition to ruling out anomalous diffusion, the mean squared displacements obtained at different diffusion times from the Karger model allowed to characterize the system’s phases by their average confining sizes, average connectivity and average apparent diffusion coefficients. The two-phase scheme was confirmed by the propagator method, which has given insights into the confining phase-geometry, found consistent with a parallel-plane arrangement. Final results indicate that water in cellulose is confined in two different types of amorphous domains, one placed at fiber surfaces, the other at fiber cores. This picture fully corresponds to the phenomenological categories so far used to identify water in cellulose fibers, namely, free and bound water, or freezing and non-freezing water.

An efficient electromagnetic interference (EMI) shielding paper with excellent water repellency and mechanical flexibility has been developed, by assembling silver nanowires (AgNWs) and hydrophobic inorganic ceramic on the cellulose paper, via a facile dip-coating preparation. Scanning electron microscope (SEM) observations confirmed that AgNWs were interconnected and densely coated on both sides of the cellulose fiber, which endows the as-prepared paper with high conductivity (33.69 S/cm in-plane direction) at a low AgNW area density of 0.13 mg/cm2. Owing to multiple reflections and scattering between the two outer highly conductive surfaces, the obtained composite presented a high EMI shielding effectiveness (EMI SE) of up to 46 dB against the X band, and ultrahigh specific EMI SE of 271.2 dB mm&ndash, 1. Moreover, the prepared hydrophobic AgNW/cellulose (H-AgNW/cellulose) composite paper could also maintain high EMI SE and extraordinary waterproofness (water contact angle &gt, 140&deg, ) by suffering dozens of bending tests or one thousand peeling tests. Overall, such a multifunctional paper might have practical applications in packaging conductive components and can be used as EMI shielding elements in advanced application areas, even under harsh conditions.

Cellulose paper, whose main component is cellulose polymer, has been widely used in oil-immersed power transformer that gradually deteriorates during transformer operation. Thermal aging is the main degradation form for cellulose paper immersed in insulation oil (oil&ndash, paper insulation) in a transformer. One of the most challenging issues in oil&ndash, paper insulation is inhibiting the aging of cellulose paper and extending its life. In this work, a comparative study was conducted on the thermal-aging characteristics of cellulose paper immersed in a novel three-element mixed insulation oil and mineral oil at 130 &deg, C for 150 days. The key parameters of cellulose paper were analysed, including the degree of polymerization (DP), thermal-aging rate, surface colour, and AC breakdown voltage. The furfural content and acidity of the oil, as well as the AC breakdown voltage of the insulation oil were also analysed. The results show that the cellulose paper immersed in novel three-element mixed insulation oil had much higher DP values than that immersed in mineral oil after the same thermal-aging time. The mixed insulation oil could significantly inhibit the thermal aging of cellulose paper and prolong its life. The thermal-aging rate of the cellulose insulation polymer immersed in mixed insulation oil is significantly lower than that immersed in mineral oil, whether in the process of oil&ndash, paper insulation continuous aging or in the process of aging after oil replacement with unused insulation oil. The furfural generated by cellulose degradation in the novel three-element mixed insulation oil was also less than that in the mineral oil. The mixed insulation oil had a higher acidity value during the thermal-aging process, which was mainly due to the natural esters in the components of the mixed insulation oil. However, the AC breakdown voltage of the mixed insulation oil was always higher than that of the mineral oil. This study offers a new perspective in inhibiting the thermal aging of cellulose polymer in insulation oil.

Surface modification of cellulosic paper is demonstrated by employing plasma assisted atomic layer deposition. Al2O3 thin films are deposited on paper substrates, prepared with different fiber sizes, to improve their barrier properties. Thus, a hydrophobic paper is created with low gas permeability by combining the control of fiber size (and structure) with atomic layer deposition of Al2O3 films. Papers are prepared using Kraft softwood pulp and thermomechanical pulp. The cellulosic wood fibers are refined to obtain fibers with smaller length and diameter. Films of Al2O3, 10, 25, and 45 nm in thickness, are deposited on the paper surface. The work demonstrates that coating of papers prepared with long fibers efficiently reduces wettability with slight enhancement in gas permeability, whereas on shorter fibers, it results in significantly lower gas permeability. Wettability studies on Al2O3 deposited paper substrates have shown water wicking and absorption over time only in papers prepared with highly refined fibers. It is also shown that there is a certain fiber size at which the gas permeability assumes its minimum value, and further decrease in fiber size will reverse the effect on gas permeability.

International audience; An Electrochemical Lateral Flow Immunosensor (ELFI) is developed combining screen-printed gold electrodes (SPGE) enabling quantification together with the convenience of a lateral flow test strip. A cellulose glassy fiber paper conjugate pad retains the marker immunoelectroactive nanobeads which will bind to the target analyte of interest. The specific immunorecognition event continues to occur along the lateral flow bed until reaching the SPGE-capture antibodies at the end of the cellulosic lateral flow strip. The rationale of the immunoassay consists in the analyte antigen NS1 protein being captured selectively and specifically by the dengue NS1 antibody conjugated onto the immunonanobeads thus forming an immunocomplex. With the aid of a running buffer, the immunocomplexes flow and reach the immuno-conjugated electrode surface and form specific sandwich-type detection due to specific, molecular recognition, while unbound beads move along past the electrodes. The successful sandwich immunocomplex formation is then recorded electrochemically. Specific detection of NS1 is translated into an electrochemical signal contributed by a redox label present on the bead-immobilized detection dengue NS1 antibody while a proportional increase of faradic current is observed with increase in analyte NS1 protein concentration. The first generation ELFI prototype is simply assembled in a cassette and successfully demonstrates wide linear range over a concentration range of 1–25 ng/mL with an ultrasensitive detection limit of 0.5 ng/mL for the qualitative and quantitative detection of analyte dengue NS1 protein.

With a large population of ageing transformers, utility asset managers are becoming increasingly interested in techniques which can help prolong the life of the transformer and optimize its efficiency in terms of economic operation and long-term performance. The performance of a transformer is affected by the condition of the insulation, which in turn affects the reliability of the network. The ageing of oil and paper results in the generation of ageing products such as moisture and acids, which further accelerate the ageing process through cyclic reactions. Thus, these ageing by-products need to be removed from the system at an appropriate stage in order to ensure the long-term performance of the transformer by slowing down the ageing process. This can be achieved through several measures, of which oil regeneration is becoming popular.In order to study the long-term effect of oil regeneration, oil samples collected from an on-site regeneration exercise performed on a 132/33 kV transformer were utilised in a laboratory-accelerated thermal ageing experiment. Oil samples collected before and after the regeneration were aged alongside new oils for comparison. Key ageing indicators, namely Total Acidity Number (TAN), moisture, Low Molecular Weight Acid (LMA) content, and High Molecular Weight Acid (HMA) content for the oil, and moisture, Low Molecular Weight Acid (LMA) content, and Tensile Index (TI) for paper were measured regularly. It was found that performance of oil after regeneration is better than that of oil before regeneration, and is even comparable to that of new oils. Slower reduction of TI of paper aged in oil after regeneration than paper aged in oil before regeneration conforms to previous findings that oil condition plays a role in determining the ageing rate of paper, and supports the statement that oil regeneration can slow down paper degradation in transformers.Oil regeneration experiment was performed on a 6.4/0.4 kV 77-year-old retired distribution transformer. Oil regeneration was conducted in two stages (stage 1 and stage 2), with the first stage aimed at ‘cleaning’ the oil and the second stage targeted at ‘cleaning’ the paper. Oil samples were collected at regular intervals throughout the process, and paper samples were collected from the transformer before oil regeneration, after stage 1, and after stage 2 of oil regeneration. It was found that oil regeneration restores oil parameters, including moisture and acidity, similar to those of new oils. Analysis of paper samples indicated a reduction in paper moisture at the end of stage 2 by nearly 40%, while LMA in paper exhibited a reduction at the end of stage 2 by around 30% on average. Similar reductions of paper moisture and acid content in the laboratory-conditioned samples provided strong evidence to the notion that oil regeneration is capable of improving the paper condition, and subsequently reduce the ageing rate of the paper insulation. It was concluded that strong evidence has been presented to show the effects of oil regeneration techniques on improving the conditions of both oil and paper under the investigated conditions. Therefore, it could be an effective way of managing the ageing asset population.

Cellulose paper specimens with and without surface modification were compared in order to study their physicochemical compatibility with quantum dots (QDs) for biochemical sensing applications. Silane and chitosan modification methods were applied. The distribution of QDs deposited on untreated paper and papers modified with silane and chitosan were investigated in order to understand the interaction between QDs and fibre. Modified papers were shown to significantly reduce the undesirable redistribution of QDs during paper drying. The retention ability and thermal resistance of QDs to the loss of fluorescence on modified papers were also studied for the purpose of determining the most suitable paper surface modification for developing QD-Paper-based analytical devices (QD-PADs). Furthermore, chitosan-modified paper was used to design QD-PADs to quantify glucose concentration in aqueous samples; the quenching effect of the enzymatic product on the fluorescent emission of QDs was used as the indicator system. The change of fluorescence of QDs was measured by a simple in-house constructed fluorescence imaging system. The detection limit of glucose was 5 mg/dL, which is comparable with other reported paper sensors for detection of glucose. Refereed/Peer-reviewed

The health of the transmission power transformers in the power system networks is critical to the reliability of electricity supply. Knowing the precise life expectancy of the transmission power transformer is of vital importance as it permits an optimised asset replacement. The traditionally regarded transmission power transformer’s life expectancy of 40 years is considered dated for the transformers in the UK according to the transformer life data in 2010. In this thesis, it is aimed to investigate the life expectancy of the transmission power transformer in the UK from three aspects: statistical analysis on historic transformer life data, thermal modelling of in-service transformers, and through the in-service transformers’ furan measurements.A detailed statistical analysis shows that deriving the transformer’s reliability at a certain age by calculating the hazard rate is inadequate, as the hazard rate at each age has a statistical range in which the confidence band width is related to the amount of the reliability data. The transformer life data in all ages are grouped together to derive a general hazard rate of 0.27%. It is concluded that the transformer life expectancy could not be derived via statistical approaches due to the limited data available at the older transformer ages.As an alternative approach, regarding the life of insulating paper as the ultimate life of a transformer, the thermal model published by the IEC transformer loading guide 60076-7 is reviewed and extended to estimate a transformer’s thermal lifetime. The model is improved in two aspects, such that Arrhenius equation is adopted to consider the paper’s practical ageing mechanism of oxidation and hydrolysis when calculating the paper’s ageing rate; and the model takes consideration of the paper’s moisture accumulation effect.The developed thermal model is used to reversely derive the generally unknown model input – hot-spot factor, by the means of regarding the scrapped transformer’s degree of polymerisation (DP) predicted thermal lives as a benchmark. Assigning the derived hot-spot factor to the field units with regard to the design family, the thermal lives of 106 in-service transformers have been estimated. To enlarge the life sample, the modelling lives are combined with the 79 scrapped transformers’ DP predicted thermal lives. The thermal life expectancy, defined as the median life of the sample set, is derived as 88 years. A series of sensitivity studies are performed to examine the derived life expectancy’s responses on the variations of load, winding-to-oil gradient, top-oil temperature rise, and the setting of winding temperature indicator.As a non-intrusive approach in transformer’s insulating paper assessment, the correlations between the 2-furaldehyde (2FAL) concentration dissolved in transformer oil and paper’s DP derived by different laboratories are reviewed which are found to differ significantly. As a first-time attempt to derive the 2FAL-DP correlation relationship for the field transformers, the paper’s DP is estimated at the age when oil was sampled using the thermal model, and is plotted with the 2FAL measurement. De Pablo’s equation is found to fit the plot of the DP estimates against the 2FAL measurements better than other function formats. The 2FAL concentrations corresponding to the paper’s critical DP levels are given using the developed 2FAL-DP correlation relationship.

Se construyó un medidor de conductividad térmica de materiales sólidos según las recomendaciones de las Normas ASTM C518 y C177. El equipo sirvió para medir la conductividad térmica como una función de la temperatura de dos materiales de desecho sólidos, cenizas de carbón y una mezcla de celulosa de papel con cemento. La conductividad de las cenizas fue tan baja como 0.073 W/mK a una temperatura de 250ºC y la conductividad de la mezcla de celulosa de papel con cemento fue de 0.241 W/mK a una temperatura de 160ºC . Esto muestra que ambos materiales tienen propiedades de aislantes térmicos como para usarse industrialmente. Las cenizas de carbón que soportan altas temperaturas pueden reemplazar la costosa fibra cerámica. A conductimeter following ASTM C518 and C177 recommendations was built in order to measure the thermal behavior of two kind of solid waste materials coal ash and cellulose paper mixed with cement. Conductivity of these materials was obtained as a function of temperature. Coal ash conductivity was as low as 0.073 W/mK at a temperature of 250ºC and the mixed cellulose paper conductivity was 0.241 W/mK at a temperature of 160ºC. It shows that both kinds of materials have competitive insulating properties. Coal ash as example can replace the expensive ceramic fiber at high temperatures.

14 pages, 10 figures, 1 table., he formation of powdered calcite from slurries containing a calcium source and carbon dioxide (industrial carbonation route) is a complex process of considerable importance nowadays. In the absence of additives, the rhombohedral morphology can be obtained in precipitation processes by using solution routes, but rarely by the industrial method where the most common morphology of precipitated calcite is the scalenohedral one. In this work, the conditions and mechanisms for producing calcite particles with various shapes and sizes have been investigated in a reaction between aqueous calcium hydroxide and compressed carbon dioxide (compressed vapour, liquid or supercritical). Influence of pressure, temperature and reaction time were analyzed. Rhombohedral calcite with a very low degree of agglomeration was obtained under supercritical conditions. The carbonation process was also applied to the in situ precipitation of calcite inside of the pores of cellulose paper., We thank Cales de Llierca S.A. for providing the slaked lime used in this work.