Search

Accurately assessing the color quality of printed products becomes intricate when optical brightening agents (OBAs) are introduced in papers, as diverse interactions occur among different ink pigments and papers containing OBAs due to variations in ink formulation chemistries. Specifically, alkali‐based pigments, commonly used as spot colors, are carefully formulated to ensure consistency across production batches. The presence of OBAs, which absorb ultraviolet light and emit it in the visible spectrum, significantly affects color perception and accuracy on paper when interacting with these inks. This research marks an initial investigation into how OBAs in paper influence the color accuracy of five distinct alkali‐based spot color paste inks using a Little Joe ink proofer. The research examines the physical, optical, and colorimetric characteristics of two paper samples‐one with OBA and one without‐ and analyzes the colorimetric changes occurring during the ink drying process. The results indicate that reflex blue, purple, and violet spot colors achieved acceptable delta E (ΔE00) value of below 3 on non‐OBA paper, with rubine red being on the borderline at 3.1 after 48 h. In contrast, purple, rhodamine red and violet achieved acceptable ΔE00 below 3 on high OBA paper. The distinct behavior exhibited by certain inks led to the conclusion that achieving a consistent proofing procedure across diverse alkali‐based ink formulations is impractical. [ABSTRACT FROM AUTHOR]

Identifying the factors that influence the citation of articles helps authors improve the impact and reach of their research. Analysis of publications in the Journal of Fish Biology between 2008 and 2021 revealed that variables such as the number of keywords, abstract length, number of authors, and page length were associated with higher impact papers. These trends applied to both review and regular papers. These findings suggest that papers that are more informative, have higher numbers of authors, and have more keywords are more likely to be cited. Adoption of some simple "best‐practice" behaviors can improve the likelihood that a paper is cited. [ABSTRACT FROM AUTHOR]

The research presented in this paper introduces a novel environmental energy‐harvesting technology that harnesses electricity from the evaporation of water using porous structural materials. Specifically, a strategy employing paper‐based hydroelectric generators (p‐HEGs) is proposed to capture the energy produced during water evaporation and convert it into usable electricity. The p‐HEGs offer several advantages, including simplicity in fabrication, low cost, and reusability. To evaluate their effectiveness, the water evaporation‐induced electrical output performance of four different p‐HEGs are compared. Among the variants tested, the p‐HEG combining wood pulp and polyester fiber exhibits the best output performance. At room temperature, this particular p‐HEG generates a short‐circuit current and open‐circuit voltage of ≈0.4 µA and 0.3 V, respectively, thereby demonstrating excellent electrical stability. Furthermore, the electrical current and voltage generated by the p‐HEG through water evaporation are able to power an LED light, both individually and in series and parallel connections. This study delves into the potential of electricity harvesting from water evaporation and establishes it as a viable method for renewable energy applications. [ABSTRACT FROM AUTHOR]

This work reports on a facile 96‐microwell paper‐based colorimetric sensor array device (PCSAD) for highly accurate pH detection toward sweat analysis. Although a pH test strip has been widely used to easily visualize pH conditions with naked eyes, its accuracy to guarantee below the decimal point in pH changes has still been a concern. In contrast, the PCSAD could detect slight pH changes because of abundant chemical information by the array design. The color gradients on the PCSAD upon changing pH conditions can be rapidly recorded by a flatbed scanner. The captured digital images of the PCSAD were treated with imaging analysis, followed by extraction of color intensities for inset data. By employing the partially overlapped detectable pH ranges of pH indicators, seamless inset data was obtained. Therefore, the PCSAD successfully discriminated against slight changes in pH conditions in human sweat with high accuracy by pattern recognition methods. [ABSTRACT FROM AUTHOR]

The global overabundance of electronic waste and ever‐increasing concerns regarding the energy‐and material‐intensive manufacturing processes associated with traditional electronics are driving the development of solution‐processed, degradable electronics. Of note, the industry‐dominating prevalence of harmful lead‐based materials in sensing and actuating devices drives the push for more eco‐friendly solution‐processed piezoelectric systems. Yet current ecofriendly multi‐material printing processes are limited by both the conventional challenges of multilayer processes as well as the low‐temperature thermal constraints of biodegradable materials. Herein, a novel approach for fabricating fully printed, sustainable piezoelectric transducers on paper substrates is presented. Low‐temperature screen‐printing processes are used to integrate non‐toxic KNbO3 layers with degradable carbon‐ or zinc‐based conductive inks into devices. The influence of electrode material on device characteristics is assessed, with effective piezoelectric coefficients reported as high as 4.6 pC N−1 and 5.1 pC N−1 for devices with carbon and zinc electrodes respectively. The potential of the developed technology is then demonstrated through the first‐ever instance of fully printed piezoelectric force sensors and acoustic speakers comprised entirely of green materials. By demonstrating entirely printable green piezoelectric devices compatible with various electrode materials, this work serves as a step towards developing more complex sustainable piezoelectric technologies in the future. [ABSTRACT FROM AUTHOR]

Automated color measurement systems have become significant components of offset lithographic printing presses for better process control and reduced job waste. Some European press manufacturers are known to offer automated color measurement equipment that is confined to polarized density readings, which is uncommon in US. Introducing polarized densitometry into an environment where unpolarized densitometry is utilized can be problematic. Print professionals are on the lookout for a solution that is evidenced by a recent feature in a post from the IDEAlliance G7 Professionals forum seeking for a methodology to convert polarized to unpolarized readings. The present study applies the Bland–Altman method together with other statistical analyses to determine if a conversion between polarized and unpolarized densitometry can be established within a limited set of parameters. Three spectrodensitometers were used to record densitometric readings of wet and dry process inks on coated and uncoated drawdown proofs. The results showed that coated papers had significantly less variation between instruments compared to uncoated papers. Wet inks had more minor variations compared to dry inks. Furthermore, pure difference values and a Mann–Whitney U test indicated differences between unpolarized and polarized densitometric readings in all cases. Finally, t‐tests performed on the resulting difference data for both unpolarized versus polarized and unpolarized versus predicted polarized that showed fixed bias by means of the computed p‐values. [ABSTRACT FROM AUTHOR]

Four photochromic spiropyran‐amylose (ASP) biobased polymers with different spiropyran (SP) grafting density, DS, ASP10 (DS = 0.12), ASP40 and ASP40PA60 (DS = 0.40), and ASP100 (DS = 0.97), are synthesized through azide‐alkyne cycloaddition of an alkynyl‐functional SP derivative onto C6‐azidated‐amylose (AN3), where the unconverted azide in ASP40PA60, ASP100, and the AN3 precursor are quenched by clicking with propargyl alcohol (PA). All ASPs are poorly soluble in trifluoroethanol, ethanol, and water but soluble in dimethyl sulfoxide, N,N‐dimethylformamide, and hexafluoroisopropanol irrespective of UV irradiation, switching reversibly the grafted SP into zwitterionic merocyanine (MC). Only ASP10 and ASP40 are slightly soluble in the low polarity tetrahydrofuran, with ASP40 showing a marked photochromism and reduction of solubility on SP→MC switching. The photochromism in solution is preserved in the solid state, although with significant differences between the still relatively fast SP→MC photoisomerization and the much slower thermal retro‐isomerization. The dynamics of both processes, evaluated in a thin spin–coated ASP100 film and a thicker ASP40 photoswitchable coating on glass and paper, is more clearly affected than in solution by the grafting density. Switching the nearly apolar SP into the zwitterionic MC does not significantly affect wettability of the slightly hydrophobic ASP40 coating. [ABSTRACT FROM AUTHOR]

Most methodologies to measure the moisture‐induced deformation (hygro‐expansion) of paper microconstituents, including fibres and interfibre bonds, are low resolution or time‐consuming. Hence, here, a novel method is proposed and validated to measure high‐resolution full‐field strain maps of paper microconstituents during hygro‐expansion, based on environmental scanning electron microscopy (ESEM). To this end, a novel climate stage enables accurate control of the relative humidity (RH) near the specimen in the ESEM from 0%–100%. The fibre surface, which is decorated a priori with a microparticle pattern, is captured during RH change. Subsequently, correlating the fibre surface using a dedicated global digital image correlation algorithm enables high‐resolution hygro‐expansion strain maps. Method optimisation involved performing contrast enhancement, scan‐correction to reduce ESEM artefacts and a background correction, resulting in a strain resolution of 6·10−4. Method validation revealed that the fibres' crystallinity is affected by the electron beam, even for minimal invasive electron beam settings. Interestingly, however, the fibres consistently exhibit conventional hygro‐expansion behaviour during the drying slopes. Using the optimised procedure, hygro‐expansion characterisation of two interfibre bonds and four interfibre bond cross‐sections revealed the competition between the low longitudinal and large transverse fibre hygro‐expansion in the bonded area. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles can improve the electrical performance of oil paper insulation. In this study, 10 nm TiO2 nanoparticles were prepared and dispersed into transformer oil, and then immerse pressboards in it to obtain nanofluid impregnated pressboards (NP). Its thermal aging was accelerated together with the reference sample at 130°C for 36 days. Analyzing the acid value in the oil, polymerization degree, surface topography, AC breakdown strength, surface flashover characteristics and surface potential decay characteristics. It was observed that TiO2 nanoparticles can reduce the acid value and improve AC breakdown strength of oil. However, the degree of polymerization and surface appearance of NP and oil impregnated pressboards (OP) during thermal aging did not differ significantly. During the aging process, the energy level of pressboard surface traps shifted first towards the shallow and then gradually towards the deep. During all the aging stages, the surface flashover voltage of NP was always higher or close to that of OP. The mechanism of TiO2 nanoparticles improving the breakdown and surface flashover characteristics of oil–paper insulation during thermal aging is discussed from the perspective of water molecules and aging by‐products adsorption and introduction of shallow traps by nanoparticles. [ABSTRACT FROM AUTHOR]

BACKGROUND: Deinking is an important part of paper recycling that involves the removal of ink particles from the paper fibres. This industrial process is important so that the fibres can be recirculated back into paper production, which enables better sustainability as fewer fresh fibres are needed. In this study, we examined five different alternative fibre materials from different agricultural residues and industrial processes for the pilot production of papers. Papers containing fibres from invasive plants (Japanese knotweed), dedicated crops (miscanthus, acacia), agricultural residues (tomato stems), and industrial waste (jute - fibres from coffee bags) were printed with water-based flexo inks and deinked with two separate processes (chemical and enzymes). Mechanical (break and tensile index, breaking length) and optical properties (ISO whiteness, brightness and CIE L*a*b* values) were measured and ink elimination IR700 and deinking efficiency was calculated for the two deinking processes. RESULTS: Enzymatic treatment improved the mechanical properties of deinked pulp in comparison with the classic chemical treatment. Mechanical strength for almost all papers increased slightly (breaking length up to 20% in tomato and jute), and the optical result (brightness) increased similarly for both processes due to the bleaching action of the colour-shaded samples, whereas the deinking efficiency showed mixed results between chemical- and enzyme-type deinking (with chemical achieving better elimination measured at 700 nm) in the typical range of ink elimination values (15-35%) for flexographic inks. This indicates further optimization of the deinking with enzymes is needed due to different alternative fibre compositions and variations of residues in the delignification processes. CONCLUSION: Using a combination of adjusted enzymatic treatment as a precursor for deinking of paper-based packaging materials sourced from alternative fibres showed promising results regarding mechanical properties, whereas the optical properties need to be improved with cellulase optimization or by using mixes of different enzymes. These kinds of paper materials printed with flexo inks were found to be successfully deinkable with the chemical ISO-based deinking protocol. [ABSTRACT FROM AUTHOR]

Nanocellulose has received enormous scientific interest for its abundance, easy manufacturing, biodegradability, and low cost. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) are ideal candidates to replace plastic coating in the textile and paper industry. Thanks to their capacity to form an interconnected network kept together by hydrogen bonds, nanocelluloses perform an unprecedented strengthening action towards cellulose‐ and other fiber‐based materials. Furthermore, nanocellulose use implies greener application procedures, such as deposition from water. The surface chemistry of nanocellulose plays a pivotal role in influencing the performance of the coating: tailored surface functionalization can introduce several properties, such as gas or grease barrier, hydrophobicity, antibacterial and anti‐UV behavior. This review summarizes recent achievements in the use of nanocellulose for paper and textile coating, evidencing critical aspects of coating performances related to deposition technique, nanocellulose morphology, and surface functionalization. Furthermore, beyond focusing on the aspects strictly related to large‐scale coating applications for paper and textile industries, this review includes recent achievements in the use of nanocellulose coating for the safeguarding of Cultural Heritage, an extremely noble and interesting emerging application of nanocellulose, focusing on consolidation of historical paper and archaeological textile. Finally, nanocellulose use in electronic devices as an electrode modifier is highlighted. [ABSTRACT FROM AUTHOR]

The absolute dating of documents is still one of the most important challenges for forensic document examiners (FDE). The potential difference between the date on a questioned document and the actual year of production of the used paper can be only 1 to 5 years. Until now, there was no analytical method with this accuracy available. This study demonstrates a method for an absolute dating of paper by using the 14C bomb peak and dating the starch in the paper. Accelerator mass spectroscopy (AMS) radiocarbon measurements were performed on starch extracts and cellulose fibers from 50 paper samples with known production year from 1950 to 2018. For most of the paper samples, the measured 14C concentration values in the starch extracts were highly correlated with the data of the 14C bomb peak calibration curve. The differences between the calibrated ages and the actual harvest years of the starch‐containing plants were only up to 3 years. The 14C concentration in the paper fibers showed a lower but significant correlation with the production year of the papers and can be used to support the dating results of the starch extracts. In order to secure the accuracy of the dating, aside from the radiocarbon measurements of the extracted starch other analytical methods or data are used, like a detailed chemical analysis of the paper composition including fiber composition and the spectroscopic analysis of the purity of the starch extracts. In practice, only starch extracts without contaminations are used for the paper dating. [ABSTRACT FROM AUTHOR]

The fabrication of the Screen‐Printed Electrode (SPE) was performed using the graphite ink to print the working (WE) and counter electrodes (CE), and silver/silver chloride path as reference electrode (RE). All the electrodes are printed in a paper substrate using screen‐printing technique. The resulting SPE is characterized using scanning electron microscopy, showing all the ink layer, and subsequently optimized. The paper sample presented the cellulose fibers entanglement, extremely rough, with highly porous network. Then the graphite ink was deposited and the surface became flat, thinner and very smooth. When the silver ink was painted on top of the graphite ink, the spherical silver particles, ranged from 2–3.5 μm in size, were observed. And finally, the silver ink was covered with a AgCl layer and the particle size becomes larger with an irregular sphere‐like phase. The images showed that the layers appear to be homogeneously distributed with good coverage. Then fabrication process was optimized concerning type of paper, the sanding process, the hydrophobic barrier, the electrode design and size. In summary, the optimized values included using the previously sanded matte paper with a mineral spirit layer. The design and size of the electrode were also tested to achieve the best electrochemical performance (design 3 with 3.5 cm). The final SPE was a miniaturized and flexible paper‐based electrochemical electrode. In order to evaluate the electrical properties, the ohmic resistance of each ink was tested using a multimeter and the obtained values were 2.18 kΩ for the graphite ink, 2.27 Ω for the silver ink and 38.33 kΩ for the silver/silver chloride ink. That can indicate the good conductivity of each ink used in the fabrication of the electrode and the correct deposition of Ag/AgCl. Finally, the electrode was used to measure the electrochemical response of K4[Fe(CN)6] in different concentrations. Then a calibration curve was obtained from the voltammograms and a linearity was observed between the current and concentration in the range of 0.50–2.00 mM. That indicates that the SPE has potential to be used as a voltammetric electrode. [ABSTRACT FROM AUTHOR]

The main insulation structure of the valve‐side winding of converter transformer bears the effect of AC and DC superimposed voltage during operation. The electric field intensity in the pressboard is much higher than that in the pressboard in the AC transformer. This condition increases the probability of failure of insulation structure. Therefore, the design and optimization of the main insulation structure of the valve‐side winding are keys to ensure the stable operation of converter transformer. This study establishes a model of the main insulation structure of the valve‐side winding of the ±1100 kV converter transformer. The influence of the insulating oil–paper configuration on the electric field distribution of the main insulation structure of the valve‐side winding is analysed, and then, an optimization idea is proposed. The oil–paper configuration includes two aspects: oil–paper insulation structural design and combination selection, that is, the influence of typical oil–paper structural design parameters and the aging state of different oil–paper combinations on the electric field distribution. Finally, the optimization idea of the oil–paper configuration for valve‐side winding of converter transformer is obtained, and the established model is optimized. [ABSTRACT FROM AUTHOR]

A precisely formulated research question is becoming increasingly important within the humanities. This applies not only to research funding applications, but also to articles, papers, and student theses. This article presents a tool allowing students to develop research questions on their own, which is open enough to allow for a wide variety of research questions, while still giving users sufficient guidance to formulate a precise question. It also offers a concrete roadmap for students to use in developing their research question. [ABSTRACT FROM AUTHOR]

The object of this study is unusual for both its material and technique. It is an oil painting on sheets of paper glued to a canvas made of linen fibres, thereby showing some execution peculiarities. It depicts the Virgin of Thessalonica in a hieratic attitude. The painting is attributed to the Salento‐born artist Giuseppe Verrio (1639) for the church of the Theatine religious Order in Lecce, Italy, in which it is still placed, on the left altar of the transept. To truly understand and appreciate a work of art, it is important to have a basic knowledge of the materials and techniques used by the artist. For a better understanding of the execution techniques and to study the original materials and those that have been added over time, the painting was examined using the following analytical techniques: microscopic examination of cross‐sections, μ‐Raman spectroscopy and pyrolysis gas chromatography‐mass spectrometry (Py‐GC‐MS). The data indicate that Verrio used different earthy, mineral and manufactured pigments, an organic dye used only on the paper, oil as a binder, and varnish as a protectant. The results demonstrate that the latter are both original and due to a subsequent restoration. [ABSTRACT FROM AUTHOR]

We propose a printed 384‐well microtiter paper‐based fluorescent chemosensor array device (384‐well microtiter PCAD) to simultaneously categorize and discriminate saccharides and sulfur‐containing amino acids for food analysis. The 384‐well microtiter PCAD requiring 1 μL/4 mm2 of each well can allow high‐throughput sensing. The device embedded with self‐assembled fluorescence chemosensors displayed a fingerprint‐like response pattern for targets, the image of which was rapidly captured by a portable digital camera. Indeed, the paper‐based chemosensor array system combined with imaging analysis and pattern recognition techniques not only successfully categorized saccharides and sulfur‐containing amino acids but also classified mono‐ and disaccharide groups. Furthermore, the quantitative detectability of the printed device was revealed by a spike and recovery test for fructose and glutathione in a diluted freshly made tomato juice. We believe that the 384‐well microtiter PCAD using the imaging analysis system will be a powerful sensor for multi‐analytes at several categorized groups in real samples. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) produced by irradiation of paper (paper‐LIG)holds substantial promise for flexible devices. This article presents paper‐LIG humidity and temperature sensors fabricated by single‐step irradiation of common filter paper with a pulsed UV laser (355 nm). The influence of the process parameters on the conversion of cellulose fibers into LIG is discussed based on the resulting morphology, structure, conductivity, and chemical composition, revealing a distinct barrier to transformation and a propagation behavior not seen under CO2 laser irradiation. The obtained material is constituted by a porous, electrically conductive network of fibers. The paper‐LIG relative humidity (RH) and temperature sensors with sensitivities of up to 1.3 × 10−3%RH−1 and ‐ 2.8 × 10−3 °C−1, respectively, are examined in terms of their linearity, reproducibility, and response time. A detailed discussion on the response mechanism is presented in the context of literature, pointing towards the absorption of water molecules in the interlayer spacing of graphene as the main reason for the increase in resistance with RH. Additionally, a contribution from variable range hopping along the ab plane of graphene at high RH is suggested. These results demonstrate the potential of paper‐LIG for low‐cost, sustainable, and environmentally friendly sensing. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to test the accommodative lag and mechanical tension theories for myopia by assessing the influence of the lag of accommodation on axial elongation by using three different near targets that are known to influence the accommodative response differently. Methods: Forty‐two young adults were recruited for the study. Axial length was measured using a non‐contact biometer, before and immediately after a 15 minute visual task, with one of the three near targets placed 20 cm from the eye: reading text from a paper, reading text from a smartphone and watching a video on a smartphone. The accommodative response was determined using an open‐field autorefractor while the participants viewed the near target monocularly. Results: Lag of accommodation was significantly different for the three tasks: watching a video (mean ± standard error of the mean [SEM] 0.92 ± 0.10 D); reading text on the smartphone (0.59 ± 0.08 D); and reading text on paper (0.24 ± 0.09 D). There was a significant (p < 0.05) increase in axial length after reading text from a paper (10.5 ± 1.9 µm after 15‐min) and reading text from a smartphone (5.2 ± 2.7 µm), but not after watching a video on a smartphone (−0.5 ± 1.7 µm, p = 0.47). Vitreous chamber depth increased significantly more with the reading tasks compared with watching a video (reading text from a paper and smartphone: 33.9 ± 4 µm and 31.7 ± 4 µm vs. watching a video on a smartphone: 14.6 ± 5 µm, p = 0.001). Conclusion: Greater changes in axial length associated with the low lag of accommodation failed to support the theory that lag of accommodation during visual tasks could be the trigger for axial elongation. Reading on paper and smartphone at the closest reading distance may stimulate high accommodative demand and axial elongation as a consequence, possibly due to increased "ciliary muscle tension" during accommodation. [ABSTRACT FROM AUTHOR]

The electrochemical literature describes a plethora of devices for various applications. Design and development of such paper‐based analytical device(PAD) for sensing applications is paramount of interest. In this work, a PAD was developed using common office‐hold items like paper, pencil, crayons and scotch tape. On a paper, a three‐electrode system was developed by simple drawing with pencils, and the accessible area was confined by creating a hydrophobic barrier using color crayons. The newly developed PAD can hold a low‐dead volume of 25 μL for the analysis and is sealed at the bottom using scotch tape. In our preliminary approach, uric acid (UA), a critical biomarker, was demonstrated as a model analyte for the application of the developed PAD as an electrochemical sensor. The sensor exhibited better analytical performance for UA sensing in a wide range (0.1–1 mM) with appreciable reproducibility, sensitivity (0.3×10−3 A M−1) and selectivity over common interferents (ascorbic acid, urea and glucose). Furthermore, the developed electroanalytical approach was validated by testing the UA in non‐invasive bio‐sample (human urine). Such a cheap, portable, disposable, biocompatible, eco‐friendly and fully‐drawn PAD paves the way for the development of affordable 'lab on paper' devices for a wide range of bioanalytical applications. [ABSTRACT FROM AUTHOR]

We report a paper-based chemosensor array device (PCSAD) for the quantitative detection of oxyanions including the herbicide glyphosate (GlyP) in aqueous media. The mechanism of the oxyanion detection relies on a coordination-binding-based sensor array. In this study, the competitive coordination binding among Zn2+, four catechol dyes, and seven oxyanions caused noticeable colour changes. The colour changes were employed for qualitative and quantitative analyses using an in-house automated image-processing algorithm with pattern recognition for digital images. A linear discrimination analysis discerned similarly structured oxyanions with 100% accuracy. The regression analysis allowed the accurate quantification of GlyP in the herbicide products with a limit of detection of 16 mg/L, which is lower than the health advisory value for children (20 mg/L) stipulated by the environmental protection agency (EPA). PCSAD is a powerful sensor device for the on-site quantification of aqueous anions for environmental assessment. [ABSTRACT FROM AUTHOR]

This work explores the design of a model predictive controller of the continuous pulp digester process consisting of the co‐current zone and counter‐current zone modeled by a set of nonlinear coupled hyperbolic partial differential equations (PDEs). The distributed parameter system of interest is not spectral, and slow–fast dynamic separation does not hold. To address this challenge, the nonlinear continuous‐time model is linearized and discretized in time utilizing the Cayley–Tustin discretization framework, which ensures system theoretic properties and structure preservation without spatial discretization or model reduction. The discrete model is used in the full state model predictive controller design, which is augmented by the Luenberger observer design to achieve the output constrained regulation. Finally, a numerical example is provided to demonstrate the feasibility and applicability of the proposed controller designs. [ABSTRACT FROM AUTHOR]

Paper evidence usually undergoes two consecutive examinations in forensic laboratories: ESDA (electrostatic detection apparatus) to detect indented impressions and a subsequent search for fingermarks by optical, physical, and chemical techniques. The ability of ESDA in visualizing fingermarks is well known. The aim of the present study is to understand better how long fingermarks can be developed with ESDA and if the different constituents of fingermarks show a different susceptibility to being developed. Several types of marks were collected from six donors on A4 standard office copy paper and tested with ESDA up to 69 days from deposition. A clear difference between natural, eccrine, and sebaceous marks emerged, being the latter ones better developed. ESDA developed standard sebaceous marks up to 16 days from deposition, whereas natural marks were visible within a few days. Eccrine marks were mainly visualized in reverse mode, despite the quality of these marks was not as good as the sebaceous marks. The appearance of the mark (standard/reverse) seemed to be correlated with time since deposition. Data suggest that the mechanism by which ESDA visualizes the fingermarks could be related to the residue (water‐soluble and/or non‐water‐soluble) available on the surface of the substrate and not yet absorbed by the paper. ESDA could act as a useful screening tool in fingermark visualization on porous surfaces, especially because it is a non‐destructive technique. Therefore, as a general procedure, it is highly recommended to acquire potential fingermarks developed by means of ESDA before proceeding with fingermark visualization. [ABSTRACT FROM AUTHOR]

Photonic and electronic devices currently face challenges in terms of improved efficiency of energy harvesting and light emission, renewable energy and materials, and the development of eco‐friendly materials. Owing to the emergence of world‐wide concerns about environmental degradation and the ensuing regulations, demand for environmentally friendly technology has been increasing in recent years. As the current technology of creating electronics and photonics devices based on semiconductors heavily relies on processes that produce a series of hazardous chemicals, development of renewable and eco‐friendly materials has become immensely important. Two of the most promising materials in this respect are silk and paper, and this progress report will investigate their unique properties for both photonic and electronic applications. These two natural materials have been intensively studied in the last decades and have shown promising aspects for use in future green technologies. [ABSTRACT FROM AUTHOR]

Transformer oil is widely used in high‐voltage transformers as a cooling and insulation medium. Electrical and thermal stresses expose transformer oil to degradation, which may produce dissolved decay products (DDPs) that are partially adsorbed on the insulation paper and accelerate the degradation of oil and paper. An evanescent field D‐shaped plastic optical fibre (POF) sensor was fabricated using the side‐polishing technique to detect DDPs in transformer oil. A laser light source and power meter were used in the prototype to measure the output power of the POF sensor. The measurement of DDPs was conducted on seven samples of insulating oil collected from the field. The sensor performance was evaluated based on different sensing areas, and the sensor sensitivity was measured. Results show an excellent correlation between the output power and DDPs. A correlation analysis was conducted amongst sensor output power, transformer oil refractive index and area under the absorbance curve. The performance of the sensor demonstrates improved linearity and sensitivity of 97.49% and 26.6779 µW/RIU, respectively. The POF sensor is easily fabricated, low cost and can be used for real‐time monitoring of high‐voltage transformers. [ABSTRACT FROM AUTHOR]

Nanoscale integration is difficult on rough surfaces despite their ubiquity and usefulness. Paper is an emerging material system because it is renewable, flexible, and lightweight. However, owing to the rough surface of paper, it is difficult to use conventional nanoscale integration methods. Herein, nanoscale printing of CdSe/ZnS quantum dots on paper using a 3D printing method with surface adaptive control of the femtoliter meniscus is demonstrated. The approach allows the direct integration of light‐emitting materials on the intact surface of paper with nanoscale lateral confinement. The 3D‐printed nanostructures can be treated as a planar pattern of the nanoscale dots when viewed from the top. The individually addressable nature of the 3D printing method enables the equalization of the printed heights, which is essential for practical use in general planar systems. This method can be used in many areas that require paper such as paper electronics, security printing, biomedical engineering, and possibly other material systems with rough surfaces. [ABSTRACT FROM AUTHOR]

The condition assessment of oil–paper insulation is a vital issue in transformer management. To investigate the effect of moisture content on the accuracy of the prediction model, accelerated ageing experiments were performed with different initial moisture content (IMC) in laboratory condition. Two types of multi-parameter lifetime prediction models, e.g. with and without consideration of IMC, were presented for comparison purpose. The authors found that a better accuracy for its prediction results could be achieved by establishing the prediction models with the consideration of IMC. Besides, models considering IMC have better economic feasibility than that without considering IMC(non-IMC) as its total cost is cheaper according to life cycle cost (LCC) calculations. In addition, failure probability based on the proposed prediction models was also calculated as a direct indicator for evaluating the oil–paper insulation status. [ABSTRACT FROM AUTHOR]

In this paper, I shall investigate whether Hegel can be considered as a sort of ancestor of McDowell's disjunctivism. If this hypothesis turns out to be plausible, then the paper offers two gains. On the one hand, it offers an innovative interpretation of the way in which Hegel conceives of our sensible epistemic access to the world. On the other hand, McDowell's own claim that his own theoretical proposal has a Hegelian sound is supported by a previously unexplored argument. I organize my analysis into three parts: I sketch McDowell's version of disjunctivism (Section 2); I analyze some passages from Hegel that I believe are important for showing some similarities between his and McDowell's argumentative strategy (Section 3); in the conclusion (Section 4), I highlight a number of core features that Hegel seems to share with McDowell's disjunctivism and I submit that they are sufficient to label Hegel the "grandfather" of McDowell's disjunctivism. [ABSTRACT FROM AUTHOR]

Nomex insulation paper has been widely used in mining dry type transformer insulation because of its excellent performance. However, the injection of space charge can affect the electrical properties of the Nomex paper and accelerate the ageing process of the insulation system, which causes the insulation system failure or even breakdown. Therefore, it is of great practical value to study the space charge characteristics of Nomex insulation paper in different hygrothermal ageing conditions. The accelerated hygrothermal ageing tests of Nomex insulation specimens with different initial moisture contents were conducted. The space charge distribution of specimens impregnated by varnish were measured by the pulsed electro‐acoustic method at different ageing stages. Simultaneously, the space charge characteristics during polarising and depolarising phases were deeply analysed. Experimental results show that negative charges accumulate between the varnish‐paper interface in specimens near the anode. The number of negative charges gradually decreases with the increase of ageing degree. Under the influence of humidity, Nomex paper can be hydrolysed, which increases the trap density and trap level. Finally, a large amount of positive and negative charges in aged specimens would result in the distortion of the local electric field, which could decrease the breakdown strength of Nomex insulation specimens and be a threat to transformer insulation. [ABSTRACT FROM AUTHOR]

Ultrasonic welding is a serious candidate in the development of methods to assemble papers and paperboards without using additional substances. However, the ultrasonic welding of papers remains a technological challenge considering the low weldability of lignocellulosic materials. This study aims to investigate on the ultrasonic welding process applied to papers in order to identify the processing conditions which favor the formation of strong welded joints. To reach such purpose, an experimental strategy was developed by combining the characterization of welded materials and the monitoring of process parameters. Experimentations were performed using a reference paper displaying a good weldability to specifically highlight the contribution of process parameters. Results indicate that the process is highly sensitive to vibration amplitude, power supplied by the high frequency generator, and sample thickness. Power seems to be a reliable indicator of the severity of the process. A strong decrease in the strength of the welded joints is observed when working with low thicknesses. It seems that the layers coated on top of papers are the main part of the material contributing in the development of adhesion at the welding joint. Overall, instrumenting the device has led to a better understanding of the ultrasonic welding of papers. [ABSTRACT FROM AUTHOR]

Paper flowers are frequently, for example as indoor decorations and in wedding bouquets. But these traditional paper flowers can only maintain static conditions, greatly affecting their sensory effects, vividness, and appreciation. The design of novel paper flowers with dynamic shape deformation could effectively broaden the application of paper flowers. Here, inspired by Chinese calligraphy, a novel polyvinyl butyral (PVB)/carbon/cellulose composite (PCC) magic paper with a sandwiched structure is prepared. The hygroscopicity difference between hydrophobic PVB and hydrophilic cellulose layer endows the PCC paper with humidity responsiveness, and the maximum bending angle is up to 91.4° upon exposure to humidity environment. Carbon in the interlayer with strong light–heat conversion capacity could further accelerate water desorption and deformation speed, resulting in highly sensitive light responsiveness. The recovery time of PCC paper from maximum bending to the original flat state is shorter than 1 s. The PCC paper has good flexibility and processability, which can be cut and assembled into flowers with different shapes, and these unique magic flowers could freely bloom and furl upon external stimulus. All these results indicate that PCC paper has great potential in the production of magic props, artworks, and intelligent household decorations fields. [ABSTRACT FROM AUTHOR]

Transformer winding hot‐spot temperature (HST) is one of the important factors affecting transformer oil–paper insulation deterioration. This study presents a three‐dimensional coupled electromagnetic‐fluid‐thermal analysis method for HST calculation in a 10 kV oil‐immersed distribution transformer, the influence of the transformer internal metal structure parts on the HST of the winding is considered in the simulation. Combining electromagnetic‐field calculation with no‐load test and load test of the transformer provides a more accurate method to determine internal losses of the transformer. Taking those power losses as heat sources, the transformer fluid‐thermal field analysis is conducted with the finite volume method. The variation of physical parameters of transformer oil with temperature is considered in the simulation. On the basis of the equivalent thermal resistance theory, the equivalent thermal conductivities of transformer windings are obtained. The simulation results deduced from the proposed method agree well with the experimental ones, which are obtained with fibre optic temperature sensors during the transformer temperature rise test, the maximum temperature difference is <3°C. The results validated the validity and accuracy of the proposed transformer HST calculation method. [ABSTRACT FROM AUTHOR]

Combining recycling of paper wastes (WPs) with extrusion‐based additive manufacturing represents a sustainable route to cellular cellulose composites tailored for lightweight construction. Particularly, shear mixing of shredded WPs with an aqueous solution of a polymer binder like polyvinyl alcohol (PVA) yields aqueous pastes suitable for 3D printing. As a shear thinning additive, both WP and microfibrillated cellulose account for enhanced shear thinning and dimensional stability. Opposite to the formation of dense WP/PVA composites by melt extrusion, 3D printing of aqueous pastes produces cellular cellulose/PVA composites exhibiting hierarchical pore architectures. In spite of low densities around 0.8 g cm−3, high Young's modulus (2.0 GPa) and tensile strength (53 MPa) are achieved. Mechanical stability, water resistance, and even flame retardancy simultaneously improve by crosslinking with glyoxal and especially by mineralization. Multimaterial 3D printing combines the 3D dispensing of cellulose/PVA pastes with the simultaneous, staged, or subsequent spraying of aqueous water glass to enable mineralization of composite surface, bulk, and interlayers. Furthermore, the glyoxal‐mediated crosslinking affords thermo‐ and moisture‐responsive cellulose/PVA composites with programmable shape change induced either by heating at 100 °C or by exposure to moisture at 37 °C. [ABSTRACT FROM AUTHOR]

Compared to bushings with lower voltage levels, the ±1100 kV converter valve‐side bushing has thicker radial insulation and longer axial insulation resulting in a more uneven temperature distribution and more severe electric field distortion, especially under high‐ambient‐temperature and high‐current conditions. Improving the distribution of the electro‐thermal coupled field of the bushing is critical for the safe operation of converter transformers. This study discusses the distribution of electro‐thermal coupled field of a typical bushing and proposes a new method to evaluate the conductivity of multiple capacitor layers under inhomogeneous axial temperatures. The effects of four bushing designs are investigated as per the adjustment of the capacitor screen structure, the replacement of the current‐carrying structure, and the modification of resin‐impregnated paper material. The results show that merely adjusting the capacitor screens is not feasible due to size limitations. By decreasing heat accumulation, adopting a single‐tube structure and increasing the thermal conductivity of resin‐impregnated paper material can reduce electric field distortion to a certain extent. Unlike the other three methods, hierarchically controlling the material resistance effectively balances the internal and external electric fields. Simulation results demonstrate the feasibility of these methods to improve the distribution of the electro‐thermal coupled field in the bushing. [ABSTRACT FROM AUTHOR]

The AC breakdown properties of Kraft paper, pressboard and the enamel insulation layer in riceoil, peanut oil and corn oil were investigated under both new and agedconditions. The ageing of paper insulators and the enamel insulation layer inoils with the open cup method was carried out at 130 oC for 500 h in an aircirculation oven. The puncture breakdown strength was determined by varying thenumber of layers and thickness of Kraft paper, while various electrode gapdistances were used to measure the surface breakdown strength. Experimentalresults show that the breakdown strength and the tensile strength of paperinsulators impregnated with these vegetable oils are comparable to that inmineral oil, and the surface breakdown strength of paper insulators is slightlyaffected by types of impregnating oils. The ageing significantly reduces boththe breakdown strength and the tensile strength of paper insulators ininvestigated oils. In addition, it was also found that the enamel layer invegetable oils withstood higher puncture breakdown strength than in mineral oil,and the ageing process significantly reduced the puncture breakdown strength ofthe enamel layer. This enamel layer was observed to markedly enhance the surfacebreakdown strength of pressboard. [ABSTRACT FROM AUTHOR]

The value of paper conductivity provides quantitative evaluation of transformer insulation health. However, proper identification of paper conductivity requires complete profile of polarisation–depolarisation current (PDC). PDC measurement being a time‐consuming offline process generally takes several hours to complete. Furthermore, magnitude of PDC becomes very low at larger value of time, which makes it sensitive to changes in environmental conditions and field noise. Hence, accuracy of paper conductivity identification can be ensured by conducting multiple measurements. This in‐turn prolongs shutdown time of equipment and become less advantageous to utilities. Here, a method is proposed which is capable of estimating paper conductivity using PDC data recorded for only 800 s. The proposed technique is tested on data collected from several real‐life in‐service transformers. In order to illustrate the accuracy of the proposed technique, paper conductivities (calculated from short duration PDC) were compared with those computed using PDC measured for 10,000 s. [ABSTRACT FROM AUTHOR]

Polarisation current profile varies non‐linearly with a magnitude of charging voltage. This implies performance parameters obtained from polarisation–depolarisation current and those measured using specialised equipment cannot always be compared. Results reported in this study suggested that the non‐linearity in insulation response can be explained in terms of the interaction between space charge and insulation conductivity. The influence of using different charging voltages and its effect on performance parameter calculation is investigated in this study with the help of laboratory samples. It is shown in this study that with the help of a trained artificial neural network, it is possible to identify the charging voltage at which insulation response exhibits minimum non‐linearity. To test the accuracy of the proposed method performance parameters measured using commercial equipment are compared with those calculated from the polarisation current profile. [ABSTRACT FROM AUTHOR]

Habitat spatial structure has a profound influence on bacterial life, yet there currently are no low‐cost equipment‐free laboratory techniques to reproduce the intricate structure of natural bacterial habitats. Here, we demonstrate the use of paper scaffolds to create landscapes spatially structured at the scales relevant to bacterial ecology. In paper scaffolds, planktonic bacteria migrate through liquid‐filled pores, while the paper's cellulose fibres serve as anchor points for sessile colonies (biofilms). Using this novel approach, we explore bacterial colonisation dynamics in different landscape topographies and characterise the community composition of Escherichia coli strains undergoing centimetre‐scale range expansions in habitats structured at the micrometre scale. The bacteria‐in‐paper platform enables quantitative assessment of bacterial community dynamics in complex environments using everyday materials. [ABSTRACT FROM AUTHOR]

To investigate the effect of aging on surface discharge of the pressboard on the shielding electrode at the end of bushing, a thermal aging preparation methods of different aging degrees of pressboard samples, surface defect model, and the associated hemisphere are designed and the step‐up method is used for subsequent experimental work. Finally, the partial discharges (PDs) under different degrees of aging are compared and combined with Fourier Transform Infrared spectra and electric field simulation. Results show that the pre‐discharge occurs mainly in the oil gap between the hemispherical electrode edge and the pressboard. The aging of the pressboard exerts no obvious effect on the discharge characteristics in the initial stage of PD; with the development of the discharge, the development of aging of pressboard leads to a higher electric field intensity acting over a greater area, the more intense the discharge, the faster the relative discharge increases and the larger its amplitude. This discharge will cause decomposition of the oil in the pores of the aging pressboard thus generating gas bubbles which will move as discharge develops. When the bubbles reach the surface of the pressboard, the local electric field intensity will increase and the discharge will become more intense. [ABSTRACT FROM AUTHOR]

The oil‐impregnated transformer is an important part of the power system. The ageing degree of the internal oil‐paper insulation determines the service life of the transformer. The low frequency of the frequency domain dielectric spectroscopy can effectively characterise the ageing degree of transformer oil‐paper insulation. For accurately and quantitatively evaluate the aging state of oil‐paper insulation of transformer, the physical process of low‐frequency electrode polarisation is theoretically analysed in this work. Considering the polarisation of the low‐frequency electrode, the theoretical expression of the dielectric response of the equivalent XY model of the transformer is obtained. Meanwhile, to verify the rationality of the theoretical expression, the accelerated thermal ageing test of the oil‐paper insulation samples were carried out under laboratory conditions. The DC conductivity, ion mobility and FDS tests of oil‐paper insulation samples were tested on ageing 5, 10 and 15 days, respectively. The test results were combined with the theoretical expression of the low‐frequency dielectric response. It is found that the difference between the calculated result and the measured result is small. Therefore, the theoretical expression of the transformer equivalent XY model can be applied to calculate the dielectric parameters of the oil‐paper insulation at low‐frequency. [ABSTRACT FROM AUTHOR]

Stretchable micropower sources with high energy density and stability under repeated tensile deformation are key components of flexible/wearable microelectronics. Herein, through the combination of strain engineering and modulation of the interlayer spacing, freestanding and lightweight MXene/bacterial cellulose (BC) composite papers with excellent mechanical stability and a high electrochemical performance are first designed and prepared via a facile all-solution-based paper-making process. Following a simple laser-cutting kirigami patterning process, bendable, twistable, and stretchable all-solid-state micro-supercapacitor arrays (MSCAs) are further fabricated. As expected, benefiting from the high-performance MXene/BC composite electrodes and rational sectional structural design, the resulting kirigami MSCAs exhibit a high areal capacitance of 111.5 mF cm−2, and are stable upon stretching of up to 100% elongation, and in bent or twisted states. The demonstrated combination of an all-solution-based MXene/BC composite paper-making method and an easily manipulated laser-cutting kirigami patterning technique enables the fabrication of MXene-based deformableall-solid-state planar MSCAs in a simple and efficient manner while achieving excellent areal performance metrics and high stretchability, making them promising micropower sources that are compatible with flexible/wearable microelectronics. [ABSTRACT FROM AUTHOR]

Induction period evaluated from time domain dielectric response of oil‐paper insulation (OPI) contains information related to heat dissipating property of oil. In the present paper, effect of aging sensitive oil properties on the value of induction period is investigated. Three types of dielectric liquids (pure mineral oil, synthetic ester, mixture of synthetic ester, and mineral oil) are considered for the present work. A neural network (NN) is used for modelling the non‐linear relationship between induction period and various oil properties. The trained network is subsequently used to study the influence of various oil properties on induction period. [ABSTRACT FROM AUTHOR]

The service life of a transformer depends on the ageing degree of the internal oil–paper insulation. In order to reliably predict the remaining service life of oil–paper insulation for a single transformer, this study proposes a method based on monitoring the performance degradation data of oil–paper insulation. In this study, the remaining life prediction model of oil–paper insulation is established according to the Wiener stochastic process. The parameters of the model are iteratively updated by using the Bayesian rule and maximum expectation algorithm. The objective of remaining service life prediction of transformer oil–paper insulation is achieved. In the laboratory, multiple groups of oil–paper insulation samples undergo an ageing test at 130°C. Certain amount of performance degradation data is obtained by continuously monitoring the oil–paper insulation. Along with the prediction method of remaining life, the accuracy of the remaining life prediction of transformer oil–impregnated paper is verified when the model parameters are updated. This is a significant guiding factor for predicting the remaining life through the performance degradation data of the continuously operating transformer. [ABSTRACT FROM AUTHOR]

The main structural component of wood fibers is cellulose, which, being highly hydrophilic, interacts with water. Cellulose‐based paper has, therefore, the same affinity with water. However, for most products such as decorative paper, this is more of a disadvantage, where water uptake both as liquid and from humid air not only weakens the paper by breaking hydrogen bonds but also alters its dimension and stability over time. The dimensional stability (ability of the paper to retain the size as its moisture content changes) is a critical parameter when the paper is submitted to printing, copying, and converting operations. Humidity can cause sheet wrinkling or warping, thus compromising the processability and the results achievable. The modification of fibers with chemical additives can be a way to improve the performance of paper against water and water vapor uptake. For this reason, several tests of horizontal diffusion of solvents were carried out to evaluate the change in uptake of as‐is paper and of papers modified by several different chemical treatments. Solvent uptake tests were performed to assess the interaction of chemically treated and untreated papers with water, dichloromethane, and ethanol. Diffusion mechanisms of the solvents flow within the fiber networks and their movement through the porous solids were analyzed. The chemical treatments of the fiber with silane, siloxane, and polyelectrolyte multilayer were found to considerably influence both solvent contact angles and absorption times of the papers, thus affecting the rate of solvent (more interestingly, of the water) diffusion into the fiber wall. By comparing all the treated and untreated samples, the contact angles with the solvents decreased by performing siloxane, oligo‐siloxane, and silane treatments. More specifically, the diffusivity rates of water decreased because of the disappearance of a fraction of the hydrophilic sites and the onset of higher crystallinity regions on the paper sheets. [ABSTRACT FROM AUTHOR]

In this work, barium sulfate (BS) fibers with a three‐level nanorod‐assembled hierarchical structure have been synthesized in a large scale by the barium oleate precursor hydrothermal method. A new kind of anti‐acid and anti‐alkali fire‐resistant BS inorganic paper has been developed using BS fibers, glass fibers and inorganic adhesive, and it has advantages such as high flexibility, good tensile strength, excellent fire‐resistant properties, excellent corrosion resistance to strong acids and strong alkalis. It is expected that the anti‐acid anti‐alkali fire‐resistant BS paper has promising applications under various high‐temperature and harsh conditions. [ABSTRACT FROM AUTHOR]

The analysis of dielectric response function obtained from the power transformer is a well‐accepted technique in insulation diagnosis. A convenient way of analysing time‐domain dielectric response φ (t) is the formulation of simple resistance−capacitance‐based circuits like the conventional Debye model (CDM) or the modified Debye model (MDM) that are capable of modelling φ (t). However, available techniques do not guarantee unique branch parameters of such circuits for a given φ (t). In fact, the branch parameters are known to depend on the curve‐fitting procedure opted during model formulation. This makes accuracy of CDM and MDM parameter‐based diagnosis techniques less reliable. Furthermore, it seems logical to analyse the time‐domain dielectric response of oil‐paper insulation using a model containing time‐varying parameters. In this study, a methodology is proposed using which such an insulation model (containing time‐varying parameters) is formulated using time‐domain insulation response. Related analysis presented suggests that the proposed model is immune to problems associated with available insulation models (containing time‐invariant parameters). The performance of the proposed model in indicating insulation condition is tested on data obtained from several real‐life power transformers. [ABSTRACT FROM AUTHOR]

Hop (Humulus lupulusL.) is an ancient perennial crop plant, native to the Northern Hemisphere. The archaeological evidence dates back to at least the sixth century ad in Europe. Hop has been used for beer brewing, in sleeping draughts, as bedding and for antibacterial purposes. Less known is that hop fibres have also been used for textiles and paper. However, it is difficult to distinguish hop from other bast fibres. Here, we present a set of fibre features, which, when found together in an archaeological/historical material within a European context, provide a strong indication that the fibres are hop. [ABSTRACT FROM AUTHOR]