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• A Bi 7 O 9 I 3 /carbon paper composite was fabricated using an in-situ annealing method. • Flexible Bi 7 O 9 I 3 /carbon paper possesses hierarchical structure. • Bi 7 O 9 I 3 /carbon paper exhibited improved photocatalytic performance. • Improved carrier separation and hierarchical structure are key to performance enhancement. Although Bi 7 O 9 I 3 is an oxygen-rich bismuth oxyiodide with higher photocatalytic activity than BiOI, its applicability for photocatalytic oxidation is limited by the rapid recombination of photogenerated carriers and poor reusability. Depositing Bi 7 O 9 I 3 on flexible macro-sized carbonaceous materials is a promising approach for promoting photogenerated electron migration and improving reusability. In this study, a composite consisting of Bi 7 O 9 I 3 supported on graphitic carbon paper (Bi 7 O 9 I 3 -CP) was synthesized via the in situ transformation of a BiOI-deposited carbon paper precursor (BiOI-CP). The as-prepared Bi 7 O 9 I 3 -CP exhibited higher visible-light-driven photocatalytic activity than both Bi 7 O 9 I 3 and BiOI-CP precursor for phenol removal. The improved photocatalytic activity of Bi 7 O 9 I 3 -CP was attributed to its hierarchical structure and promoted carrier separation, as revealed by photoluminescence, pore structure, and reactive radical analyses. Moreover, owing to its macroscale size and flexibility, the Bi 7 O 9 I 3 -CP composite could be easily operated and reused, which are favorable for practical applications. [ABSTRACT FROM AUTHOR]

The ability to draw molecules based on a given IUPAC name is a fundamental skill in organic chemistry. University students need to acquire appropriate and automated cognitive schemata to master drawing molecules before they can be considered to meaningfully be introduced to face up to reaction equations, cascades, or mechanisms. Similar to experts in organic chemistry, organic chemistry books and digital drawing tools predominantly use skeletal formulas to communicate about organic chemistry. Students must acquire the ability to use this specific representation type as part of their professional development. The present study investigates (1) which representation form beginners in organic chemistry use to draw molecules when they can choose, (2) whether errors between a paper–pencil format (free choice of representation form) and digital format (skeletal formula requested) differ, and (3) to which extent answer correctness and occurrence of error types change when a student’s preferred representation form is not available. For this investigation, a within subject design is used. The results show that the skeletal formula is used when it is automatically suggested (in the digital format) but that alternative formulas are drawn when a representation form is freely chosen (in the paper–pencil format). Violations of the octet rule appear less frequently for digital molecule-drawing tasks, but missing answers are more prominent.

This work demonstrates sensitive and low-cost piezoelectric sensors on skin-friendly, ultrathin, and conformable substrates combined with organic electrochemical transistors (OECTs) for the detection and amplification of alternating low-voltage input signals. The fully screen-printed (SP) piezoelectric sensors were manufactured on commercially available tattoo paper substrates, while the all-printed OECTs, relying on an extended gate electrode architecture, were manufactured either by solely using SP or by combining SP and aerosol jet printing (AJP) on PET substrates. Applying a low-voltage signal (±25 mV) to the gate electrode of the SP+AJP OECT results in approximately five times higher current modulation as compared to the fully SP reference OECT. The tattoo paper-based substrate enables transfer of the SP piezoelectric sensor to the skin, which in turn allows for radial pulse monitoring when combined with the SP+AJP OECT; this is possible due to the ability of the conformable sensor to convert mechanical vibrations into voltage signals along with the highly sensitive current modulation ability of the transistor device to further amplify the output signal. The results reported herein pave the way toward all-printed fully conformable wearable devices with high sensitivity to be further utilized for the real-time monitoring of electrophysiological signals.

Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0–7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.

Osteoporosis, characterized by reduced bone strength and density, poses a significant health threat, especially to the elderly, impacting their quality of life. Osteoprotegerin (OPG) acts as a decoy receptor in the RANK/RANKL/OPG system, inhibiting bone resorption. The existing methods, such as dual X-ray absorptiometry (DXA) and enzyme-linked immunosorbent assay (ELISA), have limitations, making them unsuitable for point-of-care testing (POCT). This highlights the need for molecular-level OPG testing, where microfluidic paper-based analytical devices ( $\mu $ PADs) show promise. This study presents an innovative method for OPG detection using a rotating paper-based microfluidic chip housed in a 3D-printed casing, coupled with a modified ELISA colorimetric technique. Integrating paper-based ELISA (P-ELISA) with a rotational design, the platform provides a portable point-of-care (POC) solution for OPG analysis. The system exhibits key features, including low cost (approximately 1 per test), operational simplicity, stability, and high sensitivity (2.5 pg/mL), akin to commercial ELISA kits. Notably, the device incorporates a complex trilayer architecture and an independent rotational mechanism, enabling flexible analysis of 1–12 samples based on specific requirements. This innovation offers a promising avenue for efficient OPG detection in clinical settings, surmounting current diagnostic limitations.

The evolution and mutation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are urgent concerns as they pose the risk of vaccine failure and increased viral transmission. However, affordable and scalable tools allowing rapid identification of SARS-CoV-2 variants are not readily available, which impedes diagnosis and epidemiological surveillance. Here we present a colorimetric nucleic acid assay named MARVE (multiplexed, preamplification-free, single-nucleotide-resolved viral evolution) that is convenient to perform and yields single-nucleotide resolution. The assay integrates nucleic acid strand displacement reactions with enzymatic amplification to colorimetrically sense viral RNA using a metal ion-incorporated DNA probe (TEprobe). We provide detailed guidelines to design TEprobes for discriminating single-nucleotide variations in viral RNAs, and to fabricate a test paper for the detection of SARS-CoV-2 variants of concern. Compared with other nucleic acid assays, our assay is preamplification-free, single-nucleotide-resolvable and results are visible via a color change. Besides, it is smartphone readable, multiplexed, quick and cheap ($0.30 per test). The protocol takes ~2 h to complete, from the design and preparation of the DNA probes and test papers (~1 h) to the detection of SARS-CoV-2 or its variants (30–45 min). The design of the TEprobes requires basic knowledge of molecular biology and familiarity with NUPACK or the Python programming language. The fabrication of the origami papers requires access to a wax printer using the CAD and PDF files provided or requires users to be familiar with AutoCAD to design new origami papers. The protocol is also applicable for designing assays to detect other pathogens and their variants.

On 7 September 1847, in Melbourne in the Port Phillip District of the Colony of New South Wales, David John Thomas (1813–1871) presented a paper, ‘On the inhalation of the vapour of Æther, with cases’, at an ordinary monthly meeting of the Port Phillip Medical Association. This is the earliest known presentation of a paper on etherisation in Australia. The partial publication of the manuscript in October 1847 in the Australian Medical Journalmay have led to it being returned to Thomas in Melbourne. The handwritten manuscript is now preserved in the Medical History Museum, University of Melbourne, Melbourne, Victoria. A transcript of the complete manuscript is now recorded with relevant historical notes.

The rapid advancement of modern power equipment and high-power devices has imposed increasingly stringent demands upon the mechanical and dielectric properties of electrical insulation materials. Herein, we report a poly(m-phenylene isophthalamide) (PMIA) composite insulating paper with excellent dielectric breakdown strength, reliable mechanical properties, and high thermal stability. Enhanced surface activity of PMIA is achieved through surface modification, facilitating the synergistic integration of modified PMIA (MPMIA), bovine serum albumin (BSA)/silica (SiO2), and cellulose nanofiber (CNF) into composite paper using dynamic covalent bonds and hydrogen bonding. The prepared MPMIA–BSA/SiO2–CNF composite paper exhibits a laminated stacked structure with high tensile strength (32.68 MPa) and strain at break (9.57%). Meanwhile, MPMIA–BSA/SiO2–CNF composites have excellent dielectric breakdown strength (24.75 kV/mm) and good temperature resistance. Therefore, the MPMIA–BSA/SiO2–CNF composite paper has a broad application prospect in the field of high-voltage and high-power electrical equipment insulation.

Rapid quantitative testing of illegal drugs is urgently needed for precisely cracking down on drug crimes. Herein, an optimized paper-based surface-enhanced Raman spectroscopy (SERS) platform with patterned printing of plasmonic nanoparticles was constructed for the on-site quick testing of illegal drugs in urine. The filter paper was first coated with a layer of positive-charged chitosan, so as to reduce its roughness by filling the holes of the cellulose matrix and enhance the adhesion of negative-charged silver ink. Subsequently, hydrophobic modification was performed based on the binary silylation reaction, which could obviously improve the sensitivity of the paper-based SERS substrate by concentrating the amount of analyte. Meanwhile, SERS-active silver ink was fabricated and further printed on the surface of the above modified paper with custom-designed pattern (3 × 6). The performance of this SERS platform was assessed by using crystal violet (CV) as a model tag, and the obtained results proved it possesses excellent sensitivity and reproducibility, in which the relative standard deviation (RSD) dropped remarkably. More importantly, as a proof of concept, rapid detection of standard methylamphetamine (MAMP), one of the most widely abused drugs, was achieved with a limit of detection (LOD) of 1.43 ppb using a portable Raman spectrometer. And it also had a good capability in human urine sample detection, with a correlation index (R2) up to 0.9927. This optimized paper-based SERS platform was easily manufactured, cheap, and portable, providing a new strategy for the on-site detection of illicit drugs.

In this work, a chemiluminescent sensing paper has been developed using a peroxidase biomimetic metal–organic framework as a versatile host platform. For the first time, we have explored the use of in situ growth of Prussian Blue nanoparticles (PB-NPs) onto the MIL-101(Fe) structure for the assembly of a ready-to-use sensing paper. In situ growth of PB-NPs has been performed on the surface of the MIL-101(n) family. This novel composite, named PB-NPs@MIL-101(Fe), has been successfully used to develop a sensing paper for one-step detection of H2O2in real samples (commercial disinfectant solutions and tap water samples). The as-prepared material was fully characterized, including X-ray analysis, Fourier transform infrared, scanning and transmission electron microscopies, nitrogen isotherms, and elemental analysis. After the characterization, the analytical performance of the PB-NPs@MIL-101(Fe) sensing paper was evaluated. The low-cost sensor (0.15 euro per unit) was able to detect down to 8.2 μM (corresponding to 8.2 × 10–11mol) H2O2using only 10 μL of sample with satisfactory reproducibility (relative standard deviation 17%).

Successful integration of point-of-care testing (POCT) into clinical settings requires improved assay sensitivity and precision to match laboratory standards. Here, we show how innovations in amplified biosensing, imaging, and data processing, coupled with deep learning, can help improve POCT. To demonstrate the performance of our approach, we present a rapid and cost-effective paper-based high-sensitivity vertical flow assay (hs-VFA) for quantitative measurement of cardiac troponin I (cTnI), a biomarker widely used for measuring acute cardiac damage and assessing cardiovascular risk. The hs-VFA includes a colorimetric paper-based sensor, a portable reader with time-lapse imaging, and computational algorithms for digital assay validation and outlier detection. Operating at the level of a rapid at-home test, the hs-VFA enabled the accurate quantification of cTnI using 50 μL of serum within 15 min per test and achieved a detection limit of 0.2 pg/mL, enabled by gold ion amplification chemistry and time-lapse imaging. It also achieved high precision with a coefficient of variation of <7% and a very large dynamic range, covering cTnI concentrations over 6 orders of magnitude, up to 100 ng/mL, satisfying clinical requirements. In blinded testing, this computational hs-VFA platform accurately quantified cTnI levels in patient samples and showed a strong correlation with the ground truth values obtained by a benchtop clinical analyzer. This nanoparticle amplification-based computational hs-VFA platform can democratize access to high-sensitivity point-of-care diagnostics and provide a cost-effective alternative to laboratory-based biomarker testing.

Contamination with tropane alkaloids in cereals is expected to increase globally. However, current identification tools (e.g., liquid chromatography–mass spectrometry) for tropane alkaloids are time-consuming and expensive. Furthermore, their miniaturized alternatives lack sensitivity and robustness. Therefore, there is a pressing need for inexpensive and effective screening methods. Here, an on-site applicable modular workflow for tropane alkaloid detection in buckwheat is presented. The modular workflow combines paper microfluidics and interconnectable 3D-printed sample preparation tools and was evaluated for different tropane alkaloids, including atropine and scopolamine. Furthermore, integration with an indirect competitive lateral flow immunoassay (icLFIA) for atropine detection at relevant levels was demonstrated. In the modular workflow, to minimize matrix coextraction, tropane alkaloids were extracted from the milled buckwheat cereals by a mixture of alkaline aqueous and immiscible organic solvents (extraction recoveries: 66–79%). The tropane alkaloids were subsequently concentrated with a newly developed paper-immobilized liquid-phase microextraction (PI-LPME, extraction recoveries: 34–60%, concentration factor to immobilized solution in paper: 60–108×). After the PI-LPME, with an integrated 3D-printed setup, the tropane alkaloids were directly eluted (elution recoveries: 83–93%) and detected with the icLFIA. Digital read-out of the icLFIA, by employing a hand-held reader, enabled semiquantification of atropine (IC50= 0.56 ng mL–1in standard solutions). The modular workflow was validated by analyzing 24 blank and spiked buckwheat cereal samples with 5 and 10 μg kg–1atropine. A cutoff value was established with an estimated false negative rate of 1% and estimated false positive rate of 0.68%. Therefore, the modular workflow can aid in fast, inexpensive, and on-site atropine detection by nonexperts, and when integrated with a scopolamine-specific icLFIA expanded toward scopolamine detection. Moreover, the developed sample extraction and concentration method (PI-LPME) is suitable for the analysis of many other compounds with pH-dependent polarity.

ABSTRACTFrom the late 1920s through the early 2000s, artists sometimes utilized chemically developed shading papers, or “chemigraphic” papers, to add dimensional effects to their drawings. These papers were precoated with patterns that were selectively revealed by applying a liquid developer. Drawings on these types of papers often show signs of deterioration, such as discoloration and fading of the developed patterns and staining of the paper support in areas where the developer was applied. This study investigates samples made from Grafix DuoShade chemigraphic papers and developers manufactured in the 1990s. These samples were analyzed to better understand their chemical makeup, deterioration, and preservation needs. The samples were characterized using macro X-ray fluorescence scanning and complementary spectroscopic techniques. To determine optimal storage environments, samples were artificially aged in different storage enclosures and colorimetry was used to compare the artificially aged samples to unaged controls. To determine optimal display environments, the light sensitivity of the samples before and after artificial aging was measured using microfadeometry. Based on the results, preservation recommendations for handling, storage, and display are provided.

Oil-paper insulation is the primary insulation material utilized in transformers, including converter transformer. As an environmentally friendly liquid dielectric, vegetable insulating oil is considered a good substitute for mineral insulating oil, but it still lacks application in converter transformers. Converter transformers mostly use multiple layers of insulating paper and insulating oil, leading to the existence of oil-paper interfaces. In the vegetable oil-paper sample, there is an overshoot phenomenon of charge accumulation at the oil-paper interface under the applied dc voltages. Owing to discrepancy in the mobility of injected charges and ionization charges, the initial equilibrium value of the interface charge is 12%–36% higher than the final equilibrium value. Due to the existence of the interface barrier, the interface charges remain at the high initial equilibrium value for a long time before decreasing to the final equilibrium value, which may potentially lead to the risk of partial discharge. Mitigating the fiber defects in the insulating paper aids in reducing the interface barrier and enabling charges that migrate to the vicinity of the oil-paper interface to cross the interface easily and recombine with the heteropolar charge on the other side, which not only facilitates the faster attainment of the final equilibrium value of interface charge under dc voltage but also enables the rapid dissipation of the accumulated charge shortly after the removal of the applied voltage. This characteristic is beneficial to the operation stability of converter transformers, especially in the condition of polarity inversion.

Oil-paper insulation is the “heart” of power transformer, and frequency-domain spectroscopy (FDS) is an efficient method to evaluate the insulation state of it. Nevertheless, traditional FDS test voltage is still at 200 V, and the insulation characteristics of FDS at high voltage (HV) levels are worth exploring. Therefore, this article studies the FDS characteristics of oil-paper insulation at various test voltages and proposed an evaluation method of moisture and aging degree of oil-immersed pressboard based on HV FDS. The results show that with the increase of test voltage, the ${C}'$ of mineral oil increases from 1 mHz to 10 Hz, while oil-immersed pressboard and “liquid-solid” oil-paper insulation decrease below 10 Hz; tan $\delta $ of all samples increases significantly with the increase of test voltage. The tan $\delta $ value at 0.1, 1, and 10 Hz is selected as a characteristic parameter to evaluate the moisture content of oil-immersed pressboard, tan $\delta $ at HV is more sensitive to moisture content compared with that at low voltage, and tan $\delta $ at 0.1 Hz and 7000 V increases 1130 times compared 75 times at 0.1 Hz and 200 V. The integral of tan $\delta $ , ${S}_{\tan \delta }$ , from 0.1 to 10 Hz is selected as parameters to evaluate the aging degree. The oil-immersed pressboard and distribution transformer are tested and evaluated by the above evaluation method, and the results show that the error of moisture content and aging degree evaluation result is less than 10%.

Bubbles in oil-paper insulation migrate and may finally accumulate, posing enormous insulation risks. Accurate simulation of bubble migration and accumulation is of vital importance. The cross-scale nature of micrometer-millimeter bubble movement in meter-scale oil-paper insulation structures makes macroscopic simulation methods often ignore the microscopic details of bubbles, which makes calculation accuracy hard to guarantee. In this study, bubble dynamics in oil-paper insulation are analyzed by the Euler–Lagrange approach, in which the distributed interaction on the bubble interface is simplified to lumped interfacial forces. The lumped bubble-oil drag force and bubble-paper friction are standardized measured, and effectively modeled combining the microscopic behaviors of bubbles. The accuracy of the Euler–Lagrange method with modeled interfacial forces is finally verified by experiment. Results show that the deformation of a steady-rising bubble in oil intensifies as bubble size increases, which has an enhanced effect on the drag force. The bubble-paper contact state and paper friction are affected by bubble-paper contact pressure and bubble motion inertia. The bubble slides in close contact with the paper when contact pressure dominates while sliding without contact when bubble inertia dominates. Both the drag force and paper friction are effectively modeled considering these bubble microscopic behaviors. The agreement between simulation results and experimental results of bubble trajectories and accumulation behaviors in a horizontal oil channel is satisfactory, verifying the accuracy of the simulation method with modeled interfacial forces. This method can be further coupled with multifield simulation realizing the precise bubble distribution analysis in oil-immersed power equipment.

Meta-aramid insulating paper, comprising precipitated fibers as the matrix and chopped fibers as the reinforcing skeleton, exhibits tremendous potential as a next-generation insulating material in high-voltage systems. However, its insulating performance is hampered by severe interface defects, thus limiting its industrial applications. To address this issue, an interface modification method is proposed based on the tunable electrical polarity of chopped fibers, achieved through a practical PDDA treatment, which converts the originally negative potentials of chopped fibers in pulp water to a positive state. As a result, a compact and cross-connected paper structure is formed, wherein the precipitated fibers and chopped fibers exhibit opposite electrical polarities, promoting strong intermolecular attraction and significantly reducing interface defects. We systematically investigate the electrical insulation and mechanical tensile properties of the modified papers, demonstrating remarkable improvements of up to 31% for breakdown strength and 35% for tensile strength. In addition, molecular simulations reveal enhanced compatibility at the fiber interface, driven by the modification of electrical polarity. This study presents an effective approach for designing high-performance meta-aramid paper, while also opening up possibilities for interface modification in various fiber-reinforced composite materials.

The oil-paper insulation’s aging can deteriorate the mechanical and electrical performance of the electrical power device; thus, it is necessary to evaluate the aging state of oil-paper insulation. Based on the electro-mechanical impedance technology, a novel aging state evaluation method of oil-paper insulation is proposed in this letter, which utilizes the piezoelectricity caused by the insulating paper attached to the piezoelectric material (PZT). The electro-mechanical model of the paper-PZT system is established considering the electric-vibration coupling effect and its characteristics are analyzed using the principle of stationary action. The insulating paper with different aging states, indicated by the degree of polymerization (DP), is selected to obtain the impedance characteristics of the paper-PZT system. The experimental results show the impedance amplitudes of the paper-PZT system increase with the aging degree, which can help in the nondestructive aging evaluation of the oil-paper insulation.

Moisture content significantly impacts the electrical strength of oil-paper insulation. Acquiring moisture content accurately and promptly at different points in oil-paper insulation is crucial to assess the risks associated with oil-filled equipment. Moisture primarily resides in the insulating paper within oil-paper insulation, and the change in moisture content in pressboard is a dynamic process, especially after localized dampening. Besides the exchanges between oil and paper, the predominant movement of moisture occurs within different regions of the insulating paper. Previous studies have primarily focused on moisture exchange at the interface between insulating paper and insulating oil. Due to the lack of nondestructive testing methods, exploration of the migration and diffusion of moisture within the internal structure of insulating pressboard is limited. This aspect is pivotal for accurately assessing moisture distribution within the insulation, thereby directly influencing the evaluation of insulation risks. In this study, the rapid and nondestructive sensing capabilities of terahertz (THz) spectroscopy are used to quantify moisture content in solid insulation. The integral value of the absorption coefficient spectrum within the frequency range of 0.3–1 THz serves as a characteristic parameter for quantifying moisture content in insulating paper. A 2-D moisture-diffusion model for localized dampening in pressboard is established based on the Fick model. Using this approach, the diffusion behavior of localized dampening in new and aged oil-impregnated pressboard is demonstrated, and the diffusion coefficient within the pressboard is calculated. A relationship between this coefficient and moisture concentration is determined. Finally, the obtained diffusion coefficient is used to numerically deduce 3-D localized moisture-diffusion behavior within the pressboard.

The insulating paper in oil-paper insulated transformers is subjected to significant mechanical vibration and mechanical shock, putting considerable demands on the insulating paper’s strength and resistance to deformation. Therefore, effective enhancement and accurate prediction of mechanical properties are crucial in the application of cellulose-insulating paper. In this article, modified insulating paper with different mass fractions of cellulose nanowhiskers (CNWs), nanofibrillated cellulose (NFC), and microfibrillated cellulose (MFC) are prepared. The microscopic morphology, stress-strain curves, and Young’s modulus of the modified insulating paper are measured. The modification effects of microcellulose/nanocellulose with different aspect ratios on the mechanical properties of the insulating paper are compared. 10 wt% mass fraction of CNW-modified paper exhibits the highest Young’s modulus with an enhancement of 11.99%. The mechanism of microcellulose/nanocellulose modification on insulating paper is analyzed in terms of its strength, morphology, interface, and agglomeration. The prediction of Young’s modulus of modified insulating paper under different doping concentrations is realized based on the Halpin-Tsai model for filler modification under ideal conditions, considering the effects of agglomerated and interfacial phases, on the basis of detailed experimental results and comprehensive analysis. Experimental validation shows that the error of the proposed prediction model is less than 1.57%. This study is very beneficial for nano-modification and mechanical property enhancement of cellulose paper.

Metamaterials, characterized by their unique artificial periodic structures, exhibit extraordinary abilities in controlling electromagnetic waves not found in natural materials. Metamaterial absorbers, for example, have been developed by patterning solid conductive materials on dielectric surfaces. However, the foldability limitations of solid conductors make them unsuitable as foldable metamaterial absorbers since they lose those desirable properties when folded. To address this challenge, various methods using liquid metals have emerged, but they either require often necessitate structural frames or are primarily suited for hard surfaces, limiting their foldability potential. This study proposes an innovative solution involving the deposition of liquid metal onto paper surfaces to overcome foldability constraints. We design a metamaterial absorber with a circular pattern using three sheets of printing paper bonded with a film, leveraging these adhesive properties of oxidized gallium-based liquid metal to waterproof agent coated printing paper while preventing adhesion to laser-printed toner surfaces. The experimental results show that this absorber achieves an absorption rate of more than 90% in the frequency range of 10.36–10.76 GHz while being insensitive to polarization and incidence angle. Surprisingly, our proposed absorber retains its excellent performance even after being folded and unfolded up to 50 times. This foldable metamaterial absorber made of liquid metal is a promising solution for electromagnetic wave management applications requiring flexibility and adaptability.

•CCS as wet-end additive enhances BC paper properties, improving tensile strength and achieving 97.3 % brightness.•Enhanced BC paper demonstrates suitability for use as a separator in battery fabrication processes.•CCS offers sustainable alternative in paper production with improved efficiency and structure over wood-based papers.

In this paper, four new metal–organic frameworks (MOFs) were synthesized by the solvothermal method based on two imidazolidyl flexible ligands, named, CUST-662–665, [Zn(pbbm)(HBTC)]·3H2O (CUST-662), [Cd2(pbbm)2(BTC)(NO3)·H2O]·2H2O (CUST-663), [Cd3(bbbm)3(BTC)2·4H2O]·3H2O (CUST-664), and [Zn2(bbbm)2(BTC)(HCOO)]·3H2O (CUST-665). All four MOFs with blue fluorescence show excellent performance in the detection of pollutants including Fe3+, Cr2O72–, trinitrophenol (TNP), and tetracycline antibiotics. Furthermore, the color of CUST-664 and CUST-665 changes from blue to yellow when detecting tetracycline (TC) and oxytetracycline (OTC), which can be further developed as simple and rapid field visual test paper as antibiotic detection devices. The detection limits of TNP, OTC, and TC can reach 0.36, 0.90, and 1.39 ppb, respectively, which are better than that of most of the reported fluorescence sensing materials. Moreover, CUST-662–665 display high selectivity, sensitivity, stability, and recycling efficiency. The competitive absorption between the crystals and pollutants was an important factor affecting fluorescence quenching. This work provides an experimental basis for subsequent fluorescence visualization field detection.

Commercial pH paper is a quick and simple tool for measuring a solution’s acidity/basicity, but it only provides qualitative or semi-quantitative results, and the synthetic indicator dyes within can be toxic or carcinogenic. Although pH meters enable more accurate and quantitative analysis, they are less convenient to operate and are tedious to calibrate. This presents a need for an alternative pH testing method for applications where it is not easy or possible to use a pH meter, yet quantitative results are desired. We report herein the fabrication of a pH test strip made from superhydrophobic paper and agarose-anthocyanin film discs. In the proposed method, test strips are dipped into samples and then imaged with a portable scanner (or a smartphone). The color of the film is extracted with ImageJ software (or a mobile app), using the RGB color system. By generating a calibration curve relating the film color to the sample pH using standard buffer solutions, we are able to quantify the pH of beverages and other liquids with an accuracy and precision comparable to that of a pH meter. The test strips offer the same convenience as conventional pH paper, with the added capabilities of quantitation and multiplexed testing, which presents a practical tool for point-of-need pH analysis.

Objective: Although point of care ultrasound (POCUS) use has become prevalent in medicine, clinicians may not be familiar with the evidence supporting its utility in patient care. The objective of this study is to identify the top five most influential papers published on the use of cardiac POCUS and lung POCUS in adult patients. Methods: A 14-member expert panel from the Canadian Association of Emergency Physicians (CAEP) Emergency Ultrasound Committee and the Canadian Ultrasound Fellowship Collaborative used a modified Delphi process. Panel members are ultrasound fellowship trained or equivalent, are engaged in POCUS scholarship, and are leaders in POCUS locally and nationally in Canada. The modified Delphi process consisted of three rounds of sequential surveys and discussion to achieve consensus on the top five most influential papers on cardiac POCUS and lung POCUS. Results: A total of 66 relevant papers on cardiac POCUS and 68 relevant papers on lung POCUS were nominated by the panel. There was 100% participation by the panel members in all three rounds of the modified Delphi process. At the end of this process, we identified the top five most influential papers on cardiac POCUS and lung POCUS. Papers include studies supporting the use of POCUS for accurately assessing left ventricular systolic function, diagnosing pericardial effusion, clarifying its test characteristics for pulmonary embolism, identifying pulmonary edema and pneumonia, as well as consensus statements on the use of cardiac and lung POCUS in clinical practice. Conclusion: We have created a list of the top five influential papers on cardiac POCUS and lung POCUS as an evidence-based resource for trainees, clinicians, and researchers. This will help trainees and clinicians better understand how to use POCUS when scanning the heart and lungs, and it will also help researchers better understand where to direct their scholarly efforts with future research.

Rice straw is an agricultural by-product that is considered to have the potential to be processed into pulp and various kinds of its derivative products. Pulping condition is an essential prior step to isolate cellulose from fibers. In this study, atmospheric hot soda pulping (AHSP) and soda pulping (SP) methods were successfully used to manufacture pulp and paper from rice straw residues. Pulp modification using water-soluble chitosan was performed aimed at increasing the hydrophobicity of the pulp and paper. X-ray diffraction analysis (XRD) results revealed an increased degree of crystallinity of pulp after both treatments compared to native rice straw. The significant effect of pulping process and chitosan concentration on paper hydrophobicity and its mechanical properties were conducted by performing ANOVA and Duncan tests. According to the statistical results, pulping types, chitosan concentration, and their interaction significantly affected the hydrophobicity but not the mechanical properties of paper (p< 0.05). The best hydrophobicity properties were obtained from AHSP 2% chitosan paper (water absorption of 24.23 ± 1.32% and contact angle (θe) 122.852 ± 0.268) while the best tensile properties of paper were obtained from SP 2% chitosan (tensile strength (S) 1401 N/m). However, the thermal stability was not affected by chitosan concentration. According to the micrographs by Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM–EDS) images, chitosan addition in the paper created changes in surface characteristics compared to the unmodified pulp possibly due to fiber–fiber and fine-fiber flocculation phenomenon Besides, the presence of chitosan can be seen in the N element of the EDS result.

Corn stalk is employed as a raw material to produce tissue paper and glucose for biofuel. Corn stalk pulp has a high amount of fines which makes it a problematic material for paper making as well as tissue paper. In this study, pulp was produced from whole corn stalk by soda-anthraquinone process, which contained 32% fines, generated from the pith of the starting raw material. High fines content resulted the tissue paper to have low bulk, poor water absorbance, and swelling. The fines were separated from the pulp by fiber classifier. The fines-free pulp was used for tissue paper and fines were subjected to enzymatic hydrolysis using cellulase to produce glucose for bioethanol production. The bulk, water absorbency, and porosity of pulp sheets increased with the removal of fines from the whole pulp. One-stage enzymatic saccharification treatment using cellulase enzyme was evaluated for the conversion of cellulosic fines to monomeric sugars by varying treatment time, consistency, and pH. Maximum fines conversion was observed at a temperature of 40°C, 5.0 pH, and consistency of 6% for 6-h reaction. Efficacy of the cellulase activity was evaluated by measuring sugar yield and residual dry weight of fines.

Traditional food packaging coated paper is not environmentally friendly, and there have been many studies on oil- and water-resistant paper for food packaging. However, preparing oil- and water-resistant paper that is plastic-free, fluorine-free, and environmentally friendly is still a significant challenge. In this study, oil- and water-resistant paper for food packaging are prepared by layer-by-layer assembly and mixing coating methods. The layer-by-layer assembly coated paper exhibits excellent water resistance (Cobb 60 value of 20.5 g/m2, water contact angle value of 132°). The mixed coated paper not only has good water resistance (Cobb 60 value of 27.1 g/m2, water contact angle value of 131°), but also has excellent oil resistance (kit rating value of 8/12). The oil-resistant and waterproof mechanism of the coated paper is confirmed through scanning electron microscopy. In addition, the mechanical performance and coating adhesion of the mixed coated paper are the best, with an increase in the tensile index of 73.1 %. This study provides a feasible strategy for preparing biodegradable, plastic-free, and fluorine-free food packaging oil- and water-resistant paper, which is beneficial for reducing plastic pollution.

A composite silicone emulsion-biomass polymer paper-based barrier coating material with high barrier performance was prepared by double-layer coating, and the material was tested for oil repellency. The composition-structure-property data set of the paper-based barrier materials was constructed based on the experimental data. An adaptive neuro-fuzzy inference system (ANFIS) was used to construct a prediction model of the coating structure in high-temperature environments to achieve quantitative analysis of the barrier performance in high-temperature environments. The ANFIS prediction model was constructed based on two algorithms, the grid partitioning algorithm and the subtractive clustering algorithm, and the accuracy of the model determined by the two algorithms was compared for training, validation and testing of this experimental data. The results showed that the prediction model of the grid partitioning method had a better fit with the experimental data, with a root mean square error (RMSE) value of 7.00383 and a R-squared (R2) of 0.9644 between the model prediction data and the actual data.

As a cultural carrier of historical inheritance, paper has high cultural, historical and scientific research value. But with the passage of time and the change of the environment, many paper are aging and damaged. In order to protect the paper, CMC-β-CD composite material for paper protection was synthesized by carboxymethyl cellulose as substrate, epichlorohydrin (ECH) as crosslinking agent, sodium hydroxide (NaOH) as catalyst and solvent, and water as medium, β-cyclodextrin as grafter. Through single factor experiment, the synthetic condition was obtained. The structure of the synthesized materials was characterized by infrared spectroscopy; CMC-β-CD was applied to paper reinforcement. The effects of solution concentration on the tensile strength, tearing degree, folding times, whiteness and gloss of paper were tested, and the suitable conditions for coating paper were found. The results show that the mass concentration of 2 % CMC-β-CD is coated on paper, its mechanical properties are greatly improved, the gloss is slightly increased, and the whiteness is basically unchanged, which is in line with the principle of “repairing the old as the old”.

Acidification is an important factor in the aging of paper literature. Since most of the paper is sized and the surface tension of water is high, it is usually difficult for aqueous phase deacidification agent to penetrate the paper resulting in uneven deacidification. The addition of surfactant can effectively reduce the liquid surface tension and enhance the effect of deacidification with wetting properties improvement. In this paper, polysorbate-80 and polyether-modified trisiloxane surfactants were added to sodium propionate aqueous deacidification agent separately, researching the effect of wettability on the paper literature deacidification by ultrasonic atomization. The results show that SP-TRSE is effective, the maximum enhancement of deacidification agent absorption after adding wetting additives is 238.20 %, the minimum standard deviation of water content and alkali reserve after treatment is 3.87 and 0.005 respectively, the maximum increase in the internal mass fraction of sodium is 0.29 %.

After inkjet printing onto uncoated and unsized paper, the ink is first imbibed into the interfiber pores and subsequently absorbed by the cellulose fibers. The achievable print quality depends on the rate of this pore-fiber transport. The latter is accompanied by mechanical expansion of the fibers and the paper sheet. Therefore, we systematically monitored the swelling dynamics of several paper types as a function of ink composition by means of four different measurement techniques. Using aqueous cosolvent solutions as model inks, we found an approximately exponential relation of the time scales of pore-fiber transport with the cosolvent concentration and an approximately linear relation with its molecular weight. Addition of surfactants can substantially speed-up pore-fiber transport.

This study explores the fusion of a field-effect transistor (FET), a paper-based analytical cartridge, and the computational power of deep learning (DL) for quantitative biosensing via kinetic analyses. The FET sensors address the low sensitivity challenge observed in paper analytical devices, enabling electrical measurements with kinetic data. The paper-based cartridge eliminates the need for surface chemistry required in FET sensors, ensuring economical operation (cost < $0.15/test). The DL analysis mitigates chronic challenges of FET biosensors such as sample matrix interference, by leveraging kinetic data from target-specific bioreactions. In our proof-of-concept demonstration, our DL-based analyses showcased a coefficient of variation of <6.46% and a decent concentration measurement correlation with an r2value of >0.976 for cholesterol testing when blindly compared to results obtained from a CLIA-certified clinical laboratory. These integrated technologies have the potential to advance FET-based biosensors, potentially transforming point-of-care diagnostics and at-home testing through enhanced accessibility, ease-of-use, and accuracy.

The urgent need for real-time and noninvasive monitoring of health-associated biochemical parameters has motivated the development of wearable sweat sensors. Existing electrochemical sensors show promise in real-time analysis of various chemical biomarkers. These sensors often rely on labels and redox probes to generate and amplify the signals for the detection and quantification of analytes with limited sensitivity. In this study, we introduce a molecularly imprinted polymer (MIP)-based biochemical sensor to quantify a molecular biomarker in sweat using electrochemical impedance spectroscopy, which eliminates the need for labels or redox probes. The molecularly imprinted biosensor can achieve sensitive and specific detection of cortisol at concentrations as low as 1 pM, 1000-fold lower than previously reported MIP cortisol sensors. We integrated multimodal electrochemical sensors with an iontophoresis sweat extraction module and paper microfluidics for real-time sweat analysis. Several parameters can be simultaneously quantified, including sweat volume, secretion rate, sodium ion, and cortisol concentration. Paper microfluidic modules not only quantify sweat volume and secretion rate but also facilitate continuous sweat analysis without user intervention. While we focus on cortisol sensing as a proof-of-concept, the molecularly imprinted wearable sensors can be extended to real-time detection of other biochemicals, such as protein biomarkers and therapeutic drugs.

Paper-based electronics offer a simple and cost-effective means to fabricate reconfigurable devices. In response to the problem of fixed shape and single function of most antennas, which limits their applications, a reconfigurable paper-based metamaterial antenna with 2D and 3D forms is presented for tunable operating frequency. The proposed antenna consists of two square split resonant rings fed by a coplanar waveguide. The working frequency of the 2D antenna is adjusted by the length, width, and opening size of the internal open resonant ring. While the folding angle of the antenna turns from 0° to 90°, the operating frequency of the paper-based metamaterial antenna changes from 2.759 to 4.223 GHz. In terms of 3D form, an additional resonant peak is generated by bending the paper-based metamaterial antenna, thus further realizing dual-band antenna design. After a simple process flow, a series of proposed antennas are fabricated and evaluated. The simulated and measured results both demonstrate that the proposed antenna has a good performance in turning the working band. The environment-friendly nature and pliability of paper, as well as simple fabrication procedures, make paper-based metamaterial promising candidates for future green electronics.

•Significantly improves the water and oil repellency of the paper and reduces the water vapor transmission rate.•Lignin nanoparticles were prepared by a simple method.•Enhanced barrier properties using lignin nanoparticles and cationic starch.•High value utilization of black liquor in paper industry.

Background and Aims: Highly cited papers (HCPs) can influence both research and clinical practice. They help to identify core literature and important advances in a field. This study aimed to assess the current status and prospects of South Asia COVID-19 research from the HCPs using bibliometric indicators.Methodology: COVID-19 literature from South Asia published between December 2019 and 29 November 2023 in the Scopus database was analysed. The top HCPs, having more than 200 citations, were evaluated. Information about citation counts, authors and organisations and their affiliations, year of publication, source journal, geographical origin, subject, article type, funding details, etc. were retrieved and analysed. Data and visualisation analysis was undertaken using Microsoft Excel and other bibliometric software.Results: The 298 South Asia HCPs were published from 2020 to 2023 and were cited 200–3,596 times, with a mean average of 413.9 citations per paper (CPP). Around 24.5% and 51.3% of HCPs received external funding support and were involved in international collaboration, respectively. The most productive organisations were the Postgraduate Institute of Medical Education and Research, Chandigarh, and the Indian Institute of Technology, New Delhi, while the most impactful organisations were Bai Jerbai Wadia Hospital for Children, Mumbai, and Kokilaben Dhirubhai Ambani Hospital & Medical Research Institute, Mumbai. The most productive journals were Diabetes and Metabolic Syndrome: Clinical Research & Reviews.Conclusions: This study has identified core and significant authors, organisations, journals, subject fields and significant keywords, collaborators and funding agencies involved in South Asia’s COVID-19 research.

The non-wood pulp fibers in the paper and printing industry have been in demand for economic and environmental necessity. In this communication, the agro-processing waste sugarcane bagasse (SCB) and amla pomace was used to develop a packaging application paper. The physical and mechanical properties of non-wood pulp remain an issue for further application. The synergistic effect of nanoparticle TiO2and amla pomace addition into the SCB was investigated. The developed SCB paper evaluated the physical, mechanical, and barriers to moisture. The molecular interaction between the constituents of paper was investigated with FTIR. The paper’s morphological crystallinity and surface topology behavior were observed in FESEM, XRD, and AFM analysis. The analysis results indicate that the SCB utilization approach could bring a sustainable solution for non-wood pulp. The mechanical properties of the paper have not been considerably affected by the addition of TiO2. The water vapor barrier quality improved as compared to the control bagasse paper. The microstructural topology of the paper is well elaborated through FESEM and AFM. The crystallinity of the paper has been significantly affected by the addition of TiO2. The EDX analysis confirms the elemental composition of cellulose and TiO2particles in the paper sheets. In conclusion, the results may not have significantly affected the paper’s performance. The antibacterial effectiveness of paper was determined by analyzing its ability to inhibit the growth of E. coli. It was discovered that the antibacterial activity of paper increased as TiO2concentration increased. Still, the approach to developing paper from agro-processing waste sources with nanoparticles can take a step toward a sustainable packaging solution.

• A modified PBAT pellet with qualified physical performances has been manufactured by appropriate prescription. • A waste paper fiber-reinforced PBAT composite film has been manufactured with the modified PBAT pellet, T-Die extrusion, and blade-coating process. • Lab-made modified PBAT film D exhibits excellent physical characteristics. • The feasibility of food package with lab-made modified PBAT film D has been evaluated. • Lab-made modified PBAT film D is a highly potential food package film. With polyethylene glycol-modification of waste paper fiber as the hydrophilic enhancer and prescription of polybutylene adipate terephthalate as well as antistatic agent/processing aid, a food package film with great transparency, good antistatic property, and high oxygen barrier capability have been prepared by T-Die extrusion and blade-coating procedure. To evaluate its feasibility for food package, the prototype of food container has been also manufactured, eventually examining its anti-corrosion capability for the milk. Experimental results elaborate that lab-made food package film can efficiently obstruct the entry of oxygen in the air into the food container, consequently dramatically extending the expiration date of milk. [ABSTRACT FROM AUTHOR]