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Background: Intelligent food packaging that can monitor food quality and safety is essential in modern commercial trade. Research on the fabrication of environmentally friendly colorimetric labels that can indicate the freshness of food through color changes are needed. Methods: In this study, paper-based colorimetric labels were prepared using filter paper dipped into a solution of Roselle flower extract, and their performance in monitoring shrimp spoilage was investigated. Results: The labels’ response to ammonia vapor shows a distinct color variation from red to greenish-grey, corresponding to a sharp increase in the total color difference (ΔE = 32). The labels are relatively stable during storage at 4°C for up to 20 days. In shrimp freshness monitoring, the color changes from red to purple, which corresponds to increasing levels of total volatile basic nitrogen (TVB-N), and can be observed easily with the naked eye. Conclusion: This suggests that our paper-based colorimetric labels impregnated with Roselle extract show superior performance in detecting shrimp spoilage.

Today, legal regulations, along with social awareness, have made waste management a necessity. Depending on the type of waste, technological developments have enabled an increase in the number of approaches, e.g., reusing, recycling, and manufacturing of different products. In this study, low-density boards were produced using different proportions of office waste paper, wood chips, and chopped E-glass fiber. Waste paper and glass fiber formed the middle layer of the boards and wood chips comprised the surface layers. The density, water absorption, and thickness swelling properties of the boards were investigated. Among the mechanical properties, the modulus of rupture, modulus of elasticity, and internal bond strength were determined. The use of wastepaper led to a reduction in the modulus of rupture and modulus of elasticity of the boards. An increase in the glass fiber ratio contributed positively to the water absorption and thickness swelling properties, whereas it directly led to decreases in the internal bond strength, and the modulus of rupture and modulus of elasticity values. Nonetheless, the low-density boards were able to meet the minimum modulus of rupture and modulus of elasticity specified in ANSI 208.1 standards, while only one variation met the IB requirements., U današnje je vrijeme zakonska regulativa, uz društvenu svijest, gospodarenje otpadom učinila nužnošću. Ovisno o vrsti otpada, tehnološki je razvoj omogućio povećanje broja pristupa gospodarenju otpadom, npr. pri ponovnoj uporabi, recikliranju i proizvodnji različitih proizvoda. Za ovo su istraživanje izrađene ploče niske gustoće s različitim udjelima otpadnoga uredskog papira, drvnog iverja i usitnjenih staklenih vlakana. Pritom su otpadni papir i usitnjena staklena vlakna iskorišteni za izradu središnjeg sloja, a drvno je iverje upotrijebljeno za vanjske slojeve ploča. Izrađene su ploče ispitane i utvrđena je njihova gustoća, moć upijanja vode i debljinsko bubrenje. Dodatno su određeni modul loma, modul elastičnosti i čvrstoća raslojavanja. Rezultati ispitivanja pokazali su da je uporaba otpadnog papira pridonijela smanjenju vrijednosti modula loma i modula elastičnosti. Istodobno je povećanje udjela usitnjenih staklenih vlakana imalo pozitivan učinak na vrijednosti upijanja vode i na debljinsko bubrenje, ali je izravno utjecalo i na smanjenje čvrstoće raslojavanja, modula loma i modula elastičnosti. Ipak, izrađene ploče niske gustoće zadovoljile su minimalne zahtjeve norme ANSI 208.1 glede modula loma i modula elastičnosti, a samo je jedna skupina eksperimentalno izrađenih ploča zadovoljila uvjete čvrstoće raslojavanja.

Microfluidic paper-based analytical devices (μPADs) are emerging as powerful analytical platforms in clinical diagnostics, food safety, and environmental protection because of their low cost and favorable substrate properties for biosensing. However, the existing top-down fabrication methods of paper-based chips suffer from low resolution (200 μm). Additionally, papers have limitations in their physical properties (e.g., thickness, transmittance, and mechanical flexibility). Here, we demonstrate a bottom-up approach for the rapid fabrication of heterogeneously controlled paper-based chip arrays. We simply print a wax-patterned microchip with wettability contrasts, enabling automatic and selective assembly of cellulose microfibers to construct predefined paper-based microchip arrays with controllable thickness. This paper-based microchip printing technology is feasible for various substrate materials ranging from inorganic glass to organic polymers, providing a versatile platform for the full range of applications including transparent devices and flexible health monitoring. Our bottom-up printing technology using cellulose microfibers as the starting material provides a lateral resolution down to 42 ± 3 μm and achieves the narrowest channel barrier down to 33 ± 2 μm. As a proof-of-concept demonstration, a flexible paper-based glucose monitor is built for human health care, requiring only 0.3 μL of sample for testing.

This work was developed within the scope of project i3N (LA/P/0037/2020. I.P. N. F. Santos thanks i3N for the BPD Grant BPD/UI96/5177/2020. S. O. Pereira thanks i3N for the BPD Grant BPD/UI96/5808/2017. The authors also thank Jonas Deuermeier for the XPS measurements. Publisher Copyright: © 2022 Elsevier Ltd Laser-induced graphene from paper (paper-LIG) was applied in non-enzymatic electrochemical sensing of uric acid (UA) in human urine. Paper-LIG was formed by CO2 laser modification of paper into a 3D graphene arrangement. Kinetic analysis of paper-LIG electrodes returned effective heterogeneous electron transfer standard rate constants of 1.4 × 10−3 cm s−1 and 7.8 × 10−4 cm s−1 for [Ru(NH3)6]2+/3+ and [Fe(CN)6]4−/3− redox probes, respectively. These electrodes were able to detect and quantify uric acid in PBS within the 10–300 μM range at pH between 5.6 and 7.4. At pH 7.4, a linear response (R2 = 0.999) from 10 to 250 μM was achieved, with a limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1. Paper-LIG electrodes denoted adequate selectivity in synthetic urine as well as in ascorbic acid (AA) and dopamine (DA)-containing electrolytes. Determination of urinary UA content in human samples returned a concentration of c.a. 1.8–1.9 mM, within the range for healthy individuals. Recoveries of samples spiked with 50 and 100 μM UA were 100.6% and 95.4%, respectively, with satisfactory reproducibility and stability. These cheap, lightweight, flexible, and eco-friendly paper-LIG biosensors for non-enzymatic quantification of UA in human urine pave the way to widespread application in the detection of other important biomarkers. publishersversion published

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit.

Pseudoestrogene bisphenol A (BPA) can be important ingredient of thermochromic inks, increasingly used materials in thermal printing paper, security printing, advertising, design and as temperature indicators in medicine and food industry. BPA mass fraction in thermochromic inks can be up to several percent. Hence, disposal of items with thermochromic prints pose a risk of environmental pollution. In this work BPA mass fraction was monitored during anaerobic degradation of papers with thermochromic prints in soil in both matrices: papers and soil. The degradation conditions simulated deeper layers of waste at a landfill site. Six types of papers with prints of thermochromic ink containing 2% of BPA were subjected to anaerobic degradation over up to 150 days.

As a sustainable and greener substitute for conventional paper products, hemp paper has the potential to revolutionise the paper industry. Hemp paper, which is made from hemp plant fibres, is more environmentally friendly than conventional paper made from trees and is by nature strong and resilient. Hemp paper offers a special business opportunity in light of the rising demand for eco-friendly products around the world and growing awareness of the negative environmental effects of traditional paper production. This abstract examines the advantages of hemp paper, the market's current state, and the difficulties that must be overcome to turn hemp paper into a lucrative business venture. Hemp paper has the potential to revolutionise the market by using cutting-edge production methods, addressing consumer concerns, and raising market awareness.

Oil media on paper, such as oil paintings, sketches, prints, and books, occasionally present problems associated with the effect of oil medium on the paper support, raising a composite matter of condition assessment as it depends on several factors. The present work examines the effect of linseed oil on paper and, in particular, the changes caused by three types of linseed oil on the optical, morphological, mechanical, and chemical properties of pure cellulosic paper, employing mock-ups submitted to artificial ageing in controlled conditions of relative humidity and temperature in airtight vessels. The study involved colorimetry, opacity, tensile strength, pH measurements, SEM, FTIR, and VOC analysis with GC-MS. Processing of the results has so far indicated that thermal-humid ageing caused the gradual darkening of the oil-impregnated mock-ups, as well as alterations in opacity, intense fall of pH values, and severe reductions in tensile strength, while linseed oil processing during manufacture has a significant impact. FTIR spectra have indicated that chemical changes upon ageing are in accordance with those of optical and mechanical changes, while VOC emissions are mostly associated with the drying and degradation of the different types of linseed oil.

The current data on climate change and environmental degradation are dramatic. The consequences of these changes are already having a significant impact on people's health. Physicians - as advocates of the patients, but also as citizens - have an ethical obligation to be involved in efforts to stop these changes. The European Federation of Internal Medicine (EFIM) strongly encourages the Internal Medicine societies and internists across Europe to play an active role in matters related to climate change and environmental degradation. At a national level, this includes advocating the adoption of measures that reduce greenhouse gas (GHG) emissions and environmental degradation and contributing to policy decisions related to these issues. At a hospital level and in clinical practice, supporting actions by the health sector to reduce its ecological footprint is vital. At the level of EFIM and its associated internal societies, promoting educational activities and developing a toolkit to prepare internists to better care for citizens who suffer from the consequences of climate change. In addition to advocating and implementing effective actions to reduce the ecological footprint of the health industry, recommending the introduction of these themes in scientific programs of Internal Medicine meetings and congresses and the pre- and postgraduate medical training. At a personal level, internists must be active agents in advocating sustainable practices for the environment, increasing the awareness of the community about the health risks of climate change and environmental degradation, and being role models in the adoption of environmentally friendly behaviour.

Wastewater-based surveillance of the COVID-19 pandemic holds great promise; however, a point-of-use detection method for SARS-CoV-2 in wastewater is lacking. Here, a portable paper device based on CRISPR/Cas12a and reverse-transcription loop-mediated isothermal amplification (RT-LAMP) with excellent sensitivity and specificity was developed for SARS-CoV-2 detection in wastewater. Three primer sets of RT-LAMP and guide RNAs (gRNAs) that could lead Cas12a to recognize target genes via base pairing were used to perform the high-fidelity RT-LAMP to detect the N, E, and S genes of SARS-CoV-2. Due to the trans-cleavage activity of CRISPR/Cas12a after high-fidelity amplicon recognition, carboxyfluorescein-ssDNA-Black Hole Quencher-1 and carboxyfluorescein-ssDNA-biotin probes were adopted to realize different visualization pathways via a fluorescence or lateral flow analysis, respectively. The reactions were integrated into a paper device for simultaneously detecting the N, E, and S genes with limits of detection (LODs) of 25, 310, and 10 copies/mL, respectively. The device achieved a semiquantitative analysis from 0 to 310 copies/mL due to the different LODs of the three genes. Blind experiments demonstrated that the device was suitable for wastewater analysis with 97.7% sensitivity and 82% semiquantitative accuracy. This is the first semiquantitative endpoint detection of SARS-CoV-2 in wastewater via different LODs, demonstrating a promising point-of-use method for wastewater-based surveillance.

Flexible inkjet-printed antenna is presented. The proposed antenna is designed on a synthetic paper substrate with an area of 35 × 40 mm2 to provide frequency bands for many popular wireless applications. Simulation and measurement are used to study the performances, including the frequency bands, radiation patterns, peak gains and efficiency, of the antenna in two severely bending conditions with a curvature radius of 20 mm in the forward and backward directions. The antenna printed in photo papers material could not be fully flexible due to cracks introduced to the coating material on the surface of the photo paper. Hence, the resin coated material was only suitable for curved devices. The synthetic paper material used in this paper does not have a resin coating, therefore, the antenna does not lose its flexibility and can be bent in both the forward and backward directions without any cracks. Results show that bending in these two conditions has insignificant effects on the performances of the antenna. With a curvature radius of 20 mm in the forward direction, the measured peak gain and efficiency of the antenna are in the ranges from −3 to +2 dBi and 40% to 60%, respectively. The results together with the low cost make the antenna most suitable for many flexible 5G communications devices.

This article aims to examine students' understanding of concepts in learning mathematics with the help of Folding Paper, the study in this article focuses on three factors, namely: Results of interviews with teachers of understanding mathematical concepts, results of observations of understanding mathematical concepts and the results of applying the RME learning model to fractional material. The method in this research uses descriptive qualitative. Sources of data consist of interviews with teachers, observations and tests. For data analysis techniques using quantitative and descriptive qualitative data analysis. From the results of interviews, observations and tests that students' understanding of mathematical concepts is still relatively low., Artikel ini bertujuan untuk mengkaji pemahaman konsep siswa dalam pembelajaran matematika materi pecahan yang berbantu media Folding Paper, kajian dalam artikel ini fokus tiga faktor yaitu : Hasil wawancara dengan guru pemahaman konsep matematika, hasil observasi pemahaman konsep matematika dan hasil penerapan model pembelajaran RME pada materi pecahan. Metode dalam penelitian ini menggunakan deskriptif kualitatif. Sumber data terdiri dari wawancara dengan guru, observasi dan tes. Untuk teknik analisis data menggunakan data analisis kuantitatif dan deskriptif kualitatif. Dari hasil wawancara, observasi dan tes bahwa pemahaman konsep matematika siswa masih terbilang rendah.

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

This work presents a unique approach to the design, fabrication, and characterization of paper-based origami robotic systems consisting of stackable pneumatic actuators. These paper-based actuators (PBAs) use materials with high elastic modulus-to-mass ratios, accordion-like structures, and direct coupling with pneumatic pressure for extension and bending. The study contributes to the scientific and engineering understanding of foldable components under applied pneumatic pressure by constructing stretchable and flexible structures with intrinsically nonstretchable materials. Experiments showed that a PBA possesses a power-to-mass ratio greater than 80 W/kg, which is more than four times that of human muscle. This work also illustrates the stackability and functionality of PBAs by two prototypes: a parallel manipulator and a legged locomotor. The manipulator consisting of an array of PBAs can bend in a specific direction with the corresponding actuator inflated. In addition, the stacked actuators in the manipulator can rotate in opposite directions to compensate for relative rotation at the ends of each actuator to work in parallel and manipulate the platform. The locomotor rotates the PBAs to apply and release contact between the feet and the ground. Furthermore, a numerical model developed in this work predicts the mechanical performance of these inflatable actuators as a function of dimensional specifications and folding patterns. Overall, we use stacked origami actuators to implement functionalities of manipulation, gripping, and locomotion as conventional robotic systems. Future origami robots made of paper-like materials may be suitable for single use in contaminated or unstructured environments or low-cost educational materials.

In the discipline of civil engineering, the foundation plays a crucial role in supporting and containing loads of complete structures. Therefore, a foundation needs to be strong enough to increase any structure's useful life. The soil has a direct impact on the structure's foundation. Vertisols soil is soil with unstable and weak soil that needs to be stabilized to make the soil suitable for construction purposes. The study is to determine the effectiveness of the pulverized used paper and sugarcane straw ash as stabilizers of vertisols soil in San Isidro, Nueva Ecija. Natural soil was classified as A-7-6 of AASTHO classification system and CH as group name classified by USCS classification system, indicates that the soil is high in clay. The index properties of the natural soil showed that it is poor and weak soil that is not applicable for engineering purposes. Liquid limit and plasticity index values of 60% and 35%, respectively, suggested that the soil is in high plasticity. There is a gradual decrease in the plasticity index to a value of 25% at 15% SCSA+PUP as compared to natural vertisols soil with 35%, this indicates that the soil is progressively stabilizing. In addition, there are increases in the compaction parameters and CBR value of 14.0283 kN/m3and 5.47 at 100% MDD compared to natural vertisols soil with values of 13.69476 kN/m3and 4.83 at 100% MDD, respectively. But these values fall from the requirement suggested of sub-base coarse, however, there are considerable changes in the vertisols soil using SCSA and PUP. This research aimed to determine the effectiveness of SCSA and PUP in stabilizing the vertisols soil

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The use of natural nanocomponents for increasing the mechanical strength of paper in the aerodynamic method has been investigated. Milled bacterial cellulose and a fine fraction of sulphate bleached softwood cellulose formed during grinding (secondary fines) were used as nanocomponents. The treatment with nanocomponents was carried out while moistening the fibrous layer with the use of an anti-adhesive material providing uniform one sided application of substances in the form of a suspension on the paper surface. The growth of the indicators of the mechanical strength of paper occurred due to the formation of additional hydrogen bonds and an increase in the interfacial interaction between the fibrous layer of plant cellulose and the nanocomponent. It was found that the use of a suspension of bacterial cellulose is more promising due to the low consumption of the binder with a significant increase in the mechanical strength of the paper. The application of a bacterial cellulose coating layer on aerodynamically molded eucalyptus cellulose makes it possible to increase the mechanical strength of the paper to consumer requirements with the consumption of bacterial cellulose in an amount of 0.9% to 1.5% by weight of absolutely dry eucalyptus cellulose., Исследовано применение природных нанокомпонентов для повышения механической прочности бумаги при аэродинамическом способе формования. В качестве нанокомпонентов использовали измельченную бактериальную целлюлозу и мелкую фракцию сульфатной беленой хвойной целлюлозы, образующуюся в процессе размола (вторичную мелочь). Введение нанокомпонентов проводили при увлажнении волокнистого слоя с применением антиадгезионного материала, обеспечивающего равномерное одностороннее нанесение веществ в виде суспензии на поверхность бумаги. Рост показателей механической прочности бумаги происходил за счет образования дополнительных водородных связей и возрастания межфазного взаимодействия между волокнистым слоем из растительной целлюлозы и нанокомпонентами. Установлено, что использование суспензии бактериальной целлюлозы более перспективно из-за малого расхода при значительном повышении показателей механической прочности бумаги. Нанесение покровного слоя бактериальной целлюлозы на бумагу аэродинамического формования из сульфатной беленой эвкалиптовой целлюлозы позволяет повысить значение механической прочности бумаги до потребительских требований при расходе бактериальной целлюлозы в количестве от 0.9 до 1.5% к массе абсолютно сухой целлюлозы.

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

Food safety is an issue that cannot be ignored at any time because of the great impact of food contaminants on people's daily life, social production, and the economy. Because of the extensive demand for high-quality food, it is necessary to develop rapid, reliable, and efficient devices for food contaminant detection. Microfluidic paper-based analytical devices (μPADs) have been applied in a variety of detection fields owing to the advantages of low-cost, ease of handling, and portability. This review systematically discusses the latest progress of μPADs, including the fundamentals of fabrication as well as applications in the detection of chemical and biological hazards in foods, hoping to provide suitable screening strategies for contaminants in foods and accelerating the technology transformation of μPADs from the lab into the field.