Search

Eco-friendly oil–water separation substrates are mostly recommended in the present context of the world. In the present work, biodegradable and more economical ultrahydrophobic composite material was synthesized by sol–gel method using silica nanoparticles (SiO2) and poly (methyl methacrylate-co-ethyl acrylate) polymer (PMMA) with 1H,1H,2H,2H Perfluorooctyltrichlorosilane (PFOTS) coupler, and coated on 40-grade cellulose filter paper with a dip-coating method. As-prepared surfaces achieved static contact angle more than 175° and sliding angle 3.8°. The microstructure and chemical composition of ultrahydrophobic filter paper were characterized by scanning electric microscopy (SEM), X-ray spectroscopy (EDX), and Flourier transformation infrared spectroscopy (FTIR), respectively. The coated filter paper accomplished 98% oil–water separation efficiency by filtering different oils. Besides, the SiO2 nanoparticles were enhanced the thermal and UV aging resistance. The coated surfaces also showed excellent chemical inertness, and mechanical durability tested. This research work can be employed yet for domestic and industrial applications at a large scale for oil–water separation and self-cleaning.

Low consistency (LC) refining of (chemi-)thermomechanical pulp (TMP) provides an energy efficient alternative to high consistency refining for pulp property development. However, the benefit of LC refining is often limited by excessive fibre shortening, lower tear strength and a reduction of bulk caused by the refining process. In this study, microfibres produced by LC refining of TMP and kraft pulp fibres were investigated for their reinforcement potential in high freeness mechanical pulp. Primary pulp at 645 mL Canadian Standard Freeness was LC refined to different energy targets as a baseline for mechanical and optical property development. In contrast, the same primary pulp was reinforced with different microfibre types in ratios that yielded the same specific energies of the baseline LC refined pulp. The study revealed that at equivalent energies, the addition of TMP microfibres to the high freeness primary pulp displayed tensile development identical to the LC refined pulp, with significantly improved tear and bulk. The addition of kraft microfibre to primary pulp produced the highest tensile and tear strength but compromised light scattering. Additionally, all microfibre composites showed improved elongation, as opposed to no notable change in elongation with conventional LC refining. This investigation proposes an alternative, cost-effective approach for developing high bulk, high strength mechanical pulp by limiting the extent of second stage refining and using LC refined microfibres for pulp reinforcement. The high tear–high bulk open construction of the composite paper is likely to benefit boxboard and packaging applications.

Coliforms are one of the most common families of bacteria responsible for water contamination. Certain coliform strains can be extremely toxic, and even fatal if consumed. Current technologies for coliform detection are expensive, require multiple complicated steps, and can take up to 24 hours to produce accurate results. Recently, open-channel, paper-based microfluidic devices have become popular for rapid, inexpensive, and accurate bioassays. In this work, we have created an integrated microfluidic coliform lysis and detection device by fabricating customizable omniphilic regions via direct printing of omniphilic channels on an omniphobic, fluorinated paper. This paper-based device is the first of its kind to demonstrate successful cell lysing on-chip, as it can allow for the flow and control of both high and low surface tension liquids, including different cell lysing agents. The fabricated microfluidic device was able to successfully detect E. coli, via the presence of the coliform-specific enzyme, β-galactosidase, at a concentration as low as ~10(4) CFU/mL. Further, E. coli at an initial concentration of 1 CFU mL(−1) could be detected after only 6 hours of incubation. We believe that these devices can be readily utilized for real world E. coli contamination detection in multiple applications, including food and water safety.

One of the most energy-intensive processes is the drying process. Therefore, an important task is to reduce heat consumption for drying. Various ways to improve the drying devices of paper and cardboard machines are identified. The main disadvantages of these improvements are given. The limiting factor of heat transfer from water vapor to paper is established. The dependence of thermal resistance on the thickness of the condensate layer is given. The authors have developed a new design for condensate drainage. The developed design allows installing movable siphons without replacement of steam inlet heads of the old type (for fixed siphons) with their insignificant modernization and cutting of an annular groove inside the drying cylinder. This will ensure a minimum level of condensate and eliminate the possibility of suction of steam into the condensate return system. Additionally, this will reduce thermal resistance, heat loss, and reduce energy consumption for paper drying as a whole. Keywords: paper drying, moisture content, drying cylinder, thermal resistance, heat transfer.

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

Around 60% of the paper worldwide is made from recovered paper. Especially adhesive contaminants, so called stickies, reduce paper quality. To remove stickies but at the same time keep as many valuable fibers as possible, multi-stage screening systems with several interconnected pressure screens are used. When planning such systems, suitable screens have to be selected and their interconnection as well as operational parameters have to be defined considering multiple conflicting objectives. In this contribution, we present a Mixed-Integer Nonlinear Program to optimize system layout, component selection and operation to find a suitable trade-off between output quality and yield.

The utilization of nitrophenols as raw materials for the synthesis of dyes, explosives, pesticides, and pharmaceuticals has increased the presence of nitrophenols as pollutants in industrial and agricultural wastewater. Similarly, the wide application range of rhodamine 6G and methylene blue enable their potential as pollutants of surface and ground waters. Both classes of chemicals can change water ecosystems dangerously. In this study, filter paper-based silver nanoparticles are prepared as catalysts for reduction of 4-nitrophenol to 4-aminophenol and for degradation of rhodamine 6G and methylene blue. This method avoids utilization of toxic reagents and is simple and inexpensive. The formation of the silver nanoparticles on filter paper was characterized using different techniques, such as scanning electron microscopy, X-ray diffraction, and surface-enhanced Raman spectroscopy. In the presence of sodium borohydride, the silver nanoparticles coated filter paper was able to reduce 4-nitophenol to 4-aminophenol within a short period of time. It has been found that, the nanocatalyst can be recycled and recovered from the reaction solutions easily without losing its high efficiency. Additionally, we demonstrated the potential of the substrate to study the in situ reduction reaction via surface-enhanced Raman spectroscopy.

Biosensors made entirely of paper are becoming increasingly popular due to their low cost, facile fabrication, and lightweight portability for in-field measurements. However, it is difficult to store nanoparticles in paper substrates without irreversibly binding them to the cellulose matrix. This makes it challenging to fabricate biosensors incorporating nanoparticle probes in paper-based reservoirs. Here, we overcome this limitation with a new method for storing protein-decorated nanoparticles on paper substrates that also allows to release them on demand. It consists of spotting nanoparticles onto pieces of filter paper previously modified with polystyrene sulfonate. Gold nanoparticles modified with avidin or antibodies can be easily transferred from the dry reservoir to a receiving wet piece of paper by simply pressing with the finger or a clamp. Paper-based immunosensors incorporating the reservoir enabled the detection of glycoprotein B from human cytomegalovirus in serum with a limit of detection of 0.03 ng mL-1 and a total assay time of only 12 min. The low limit of detection obtained with a short assay time along with the long shelf-life of the reservoirs make the proposed paper-only biosensors ideal of point-of-care diagnostics.

Environmentally recalcitrant pollutants (chromium and sulphate) from mixed effluents of tannery and paper mills were treated simultaneously using highly metal-resistant dissimilatory sulphate-reducing bacteria. The remedial efficiency of the bacteria appeared zero when the bacterial pure culture was employed without the addition of any growth substrate from external source, while the bacterial sulphate reduction and consequent metal removal appeared maximum when sodium lactate was added as growth substrate in another set of experiments. In this set of experiments, almost 100% precipitation of the chromium (700 ppm) occurred in the first 7 days of anaerobic incubation. Sulphate was also removed totally (1225 ppm) in the first 7 days of incubation. pH of the media remained in the neutral to slightly basic range throughout the experimental trial. The achievement of maximum remedial efficiency also depicts the ultimate preference of lactate as carbon source by sulphate-reducing bacteria. The outcomes of the present investigation can be fruitful for designing efficient, environment-friendly and economical bioremedial strategies.

Purpose The purpose of this paper is to study friction and wear properties of three types of steels against paper-based friction disc, including 65Mn, 20#steel and 30CrAl, so as to obtain the appropriate working conditions for different friction materials in the transmission system. Design/methodology/approach Based on actual working conditions, pin-on-disc tests are conducted on a universal material tester. The two evaluation indexes, including average friction coefficient and variation coefficient, are introduced to analyze the different friction properties among three types of steel. Furthermore, the temperature-dependent wear pattern and wear depth are subsequently studied. Findings The results show that 65Mn is more suitable for working under heavy load and low velocity, but 30CrAl and 20#steel are suitable for working under light load and high velocity. Moreover, wear primarily occurs on paper-based material and peaks at about 325. Practical implications This research of different materials and friction property for friction pairs is helpful to improve the performance and prolong the service life of transmission systems. Originality/value Suitable working conditions of different friction materials are obtained, and the correlation between wear and decomposition in high temperature is verified.

The pulp and paper industry in contrast to other manufacturing industries consumes a large amount of energy and emits pollutants along with greenhouse gases. The waste generated from the pulp and paper industry causes severe harm to the aquatic life, disturbs the food chain, and also causes various health implications. In this review, we have highlighted some of the primary pollutants released from the industry and their health hazards. Strict action and implementation of the regulatory model is required in this industrial sector for environmental compliance. The environmental pollution caused by the pollutants poses a threat to aquatic life as well as to plants and human beings. The effect of pollutants on the environment has been assessed many times, but their mitigation still has a significant challenge. This review highlights some recent techniques to reduce pollutants from the pulp and paper industries. Among these techniques, microbial fuel cells, anaerobic digestion, bleaching technologies, cleaner production, and transformation pathways are the most used techniques. These will help in understanding the risk of pollutants released from the industry and the techniques will help in tackling these pollutants for a sustainable environment development.

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

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

Lithium-ion (Li-ion) batteries have been fabricated in various ways to improve flexibility. Flexibility could be enhanced via active materials, separators, electrodes, and electrolytes, which could then be integrated to form flexible electronic devices with promising electrochemical properties compared to traditional non-flexible Li-ion batteries. Recent progress towards flexible Li- ion batteries fabrication, materials, and their electrochemical properties are investigated in this review. Additionally, recent developments in electronic devices utilizing flexible batteries and their future applications are explored. Portable and wearable electronics, as the primary beneficiaries of the flexible, rechargeable, and high-performance Li-ion batteries, are examined. In the end, various applications and challenges of flexible batteries in healthcare and various energy storage systems, considering practical implementation, are argued.

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

Studies have shown that reinforced paper-based friction material with 600 µm carbon fiber length possesses a high dynamic friction coefficient but is subjected to abrasive wear during sliding contact. This work is devoted to further investigate the effect of operating variables on this friction material subjected to high operating conditions. A pin-on-disc test was carried out to determine the tribological behavior of this friction material sliding against 65Mn steel. The friction and wear rate results from measurements were discussed. The highest friction value of about 0.3 was obtained by varying the applied load at 120 N while the lowest friction value close to 0.02 was obtained when the sliding speed was 0.026 m/s. Increasing the sliding speed above 0.30 m/s caused constant temperature (175 °C) to fluctuate due to high friction heat generation on the sliding surface. The highest wear rate was 1.42 × 10−15m3/Nm by varying the sliding speed at 1.31 m/s. In contrast, the lowest wear rate was 2.1 × 10−16m3/Nm when the temperature was at 400 °C.

In order to improve the efficiency of disease diagnosis and environmental monitoring, it is desirable to detect the concentration of proteins and metal ions simultaneously, since the current popular diagnostic platform can only detect proteins or metal ions independently. In this work, we developed a colorimetric microfluidic paper-based analytical device (µPAD) for simultaneous determination of protein (bovine serum albumin, BSA) and metal ions [Fe(III) and Ni(II)]. The µPAD consisted of one central zone, ten reaction zones and ten detection zones in one device, in which reaction solutions were effectively optimized for different types of chromogenic reactions. Fe(III), Ni(II) and BSA can be easily identified by the colored products, and their concentrations are in good accordance with color depth based on the established standard curves. The detection limits are 0.1 mM for Fe(III), 0.5 mM for Ni(II) and 1µM for BSA, respectively. Best of all, we demonstrated the efficiency of the µPAD with accurate detection of Fe(III), Ni (II) and BSA from river water samples within 15 minutes. The µPAD detection is efficient, instrument-free, and easy-to-use, holding great potential for simultaneous detection of cross type analytes in numerous diagnostic fields.

Propofol is a widely used intravenous anesthetic agent in sedation and general anesthesia. To improve the safety and maintain the depth of anesthesia, it is important to develop a rapid, sensitive, and reliable method to monitor the concentration of propofol in blood during anesthesia continuously. Here, we present a novel strategy based on paper spray ionization-mass spectrometry (PSI-MS) to detect propofol. Samples (in 10 μL) were mixed with methanol as protein precipitation solvent and 2,6-dimethylphenol as internal standard. Protein micro-precipitation was achieved with methanol by vortexing and centrifuging for 5 s each, and propofol was extracted to the supernatant. PSI-MS was performed in negative ionization mode, and MS signal lasted for 1 min. The analysis of a single sample was completed within 2 min. The area ratios of propofol to internal standard were calculated for quantification. Limit of detection of 5.5 ng mL−1 and limit of quantification of 18.2 ng mL−1 were achieved for propofol in whole blood. Calibration curve was linear in the range of 0.02–10 μg mL−1. The developed method was used successfully in monitoring the propofol concentration in 3 patients’ whole blood during anesthesia, showing its further application in controlling and feeding-back target concentration infusion.

This work describes the log-MAP (BCJR) algorithm implementation of a close to capacity dirty paper coding CODEC. The CODEC consists of eight deep pipeline processors. It decodes blocks of 975 bits in 26.9 ms using less than 9.7% of low-cost FPGA (and no DSP blocks). Two pipelines, for alpha and beta, calculate the values of gamma (of the BCJR) to reduce the storage requirements. The final log-likelihood ratio (LLR) is calculated together with alpha, reusing intermediate results. The number of bits used by the different signals of the processor is easily configurable. It was set to six bits to the channel measure signals and eight bits to log of probability signals like alpha, beta, and others. The CODEC clock was 100 MHz. The achieved bit rate is 36.2 Kbps per CODEC, but multiple CODECs can be fit into a single chip. The CODEC is 3.49 dB from the channel capacity.

PurposeCorrect and well-planned maintenance based on modern global methods directly affects efficiency, quality, direct production costs, reliability and profitability. The selection of an optimal policy for maintenance can be a good solution for industrial units. In fact, by managing constraints such as costs, working hours and human workforce causing sudden equipment failure, production and performance can increase.Design/methodology/approachTherefore, in this research a model was presented to select the best maintenance strategy at Kaghaz Kar Kasra Co of Iran. In this study, it was tried to integrate the two techniques of goal programming and the technique for order of preference by similarity to ideal solution (TOPSIS) to prioritize maintenance strategies. First, all factors affecting maintenance were identified, and based on the Best Worst Method (BWM) the degree of their importance was determined.FindingsAfter the evaluation, only 14 criteria in the 4 dimensions of cost, added value, safety and feasibility were selected. The highest points were given to the criteria of equipment cost and depreciation, equipment and personnel performance, equipment installation time and technical feasibility, respectively. In the next stage, using the TOPSIS method the item of maintenance strategy was ranked, and the 3 strategies of preventive maintenance (PM), predictive maintenance (PDM) and corrective maintenance (CM) were chosen. Modeling was performed utilizing a goal programming approach to select the optimal maintenance strategy for 13 devices. All the technical specifications, cost limits and the device time were extracted. After the model was finished and solved the best item for each device was specified.Originality/value1. Developing a goal programming model and decision-making dashboard. 2. Identifying the criteria and factors affecting the selection of the maintenance strategy for paper production Industry

Microfluidic paper-based analytical devices (μ-PADs) fabricated in Japan were employed for the determination of total chromium (Cr) in water, soil, and lettuce irrigated with wastewater in Ethiopia. The μ-PADs, which were printed by wax printing in Japan, were transported to Ethiopia and prepared for the determination of total Cr by adding appropriate reagents to the pretreatment and detection zones. Soil and lettuce samples were determined by the μ-PADs and a UV-Vis spectrophotometer in Ethiopia. A paired t-test showed that the mean total Cr concentrations determined in the soil and lettuce samples were not significantly different between μ-PADs and UV-Vis spectrophotometric analysis at the 5% level of significance. This implies that the μ-PADs have good accuracy and reliability, and could be employed to monitor Cr in environmental samples. We found that the total Cr concentrations in all soil and lettuce samples were above the permissible limit. Moreover, evaluating Cr contamination level using the geo-accumulation index indicated that the soils were contaminated with Cr moderately to heavily. Thus, the present work successfully demonstrated the potential of remote investigations of pollution in a less-equipped laboratory by transporting the μ-PADs fabricated in another laboratory.

Advancements in technology have led to the use of smartphones as biosensor detectors. However, it is difficult to obtain stable color information of colorimetric sensors using multiple smartphones owing to different light conditions and image correction operations. In this study, we attempted color detection of the colorimetric paper chip using smartphone-embedded light-emitting diode (LED) and simple transformation calculation. This method enables the acquisition of stable color information using different smartphones by reducing the influence of external light sources. Moreover, we studied characteristics such as convergence and distinction of detection result details by the manufacturers and smartphones. These findings suggested the necessity of classification criteria for the use of smartphones to achieve optimal detection. In addition, white and black references were used to set the standard for color correction of various light sources. Based on our results, we conclude that this approach presents the possibility of smartphone-based colorimetric detection in practical applications.

The use of dielectric nanofluids has been recently proposed as a method to improve the insulation system of transformers. It has been widely reported that these liquids present superior dielectric properties than conventional dielectric liquids and have a better behavior as cooling agents. Nevertheless some aspects need to be addressed before these materials are applicable to real equipment. This paper analyzes the interaction between dielectric nanofluids and the cellulose materials that constitute the solid insulation of transformers. The impregnation process of a transformer has been emulated in order to obtain samples of solid insulation impregnated with a Fe3O4 based nanofluid. The samples have been subjected to ICP testing and CryoSEM observation, complemented with the determination of the EDX sprectrum. The interaction between the nanoparticles and the cellulose fibers has been investigated finding that bonds are established between them when cellulose is impregnated with nanofluids. This research was funded by the Spanish Ministry of Economy and Competitiveness. Grant Number DPI2015-71219-C2-2-R and Spanish Ministry of Innovation. Grant Number PID2019-107126RB-C21.

Microfluidic paper-based analytical devices (μPADs) as a potentially powerful analytical platform have recently gained significant attention for on-site monitoring of heavy metal ions, which are one of the most significant environmental concern because of non-degradability and high toxicity. The commonly applied μPADs suffers from some defects, such as heterogeneous deposition of reagent, resulting in poor detection limits and low sensitivity. So, in this work, a three-dimensional origami μPAD combined with PVC Membrane was developed, which can manage problems of movement of colored products or leaching out the dye and leading to color heterogeneity in the detection zones. Furthermore, a waste layer was added to μPAD for loading of more amounts of the analyte, which results in improvement of detection limit. As a proof of concept, the μPAD was used for the analysis of Cu2+ ion. For this purpose, pyrocatechol violet and chrome azurol S as colorimetric reagents were doped into PVC membrane and injected in the detection zone. The proposed μPAD was presented good linearity in the ranges of 5.0–1400.0 and 5.0–200.0 mg L−1, and the limits of detections of 1.7 and 1.9 mg L−1 in presence of chrome azurol S and pyrocatechol violet, respectively.

A two-step process involving coagulation-flocculation followed by solar photocatalysis – based Advanced Oxidation Process (AOP) using TiO2-Reduced Graphene Oxide (TRGO) nanocomposite as catalyst ha...

As a global shift continues to occur in high burden diseases toward developing countries, the importance of medical diagnostics based on point-of-care testing (POCT) is rapidly increasing. However, most diagnostic tests that meet clinical standards rely on high-end analyzers in central hospitals. Here, we report the development of a simple, low-cost, mass-producible, highly sensitive/quantitative, automated, and robust paper/soluble polymer hybrid-based lateral flow biosensing platform, paired with a smartphone-based reader, for high-performance POCT. The testing architecture incorporates a polymeric barrier that programs/automates sequential reactions via a polymer dissolving mechanism. The smartphone-based reader with simple opto-mechanical parts offers a stable framework for accurate quantification. Analytical performance of this platform was evaluated by testing human cardiac troponin I (cTnI), a preferred biomarker for the diagnosis of myocardial infarction, in serum/plasma samples. Coupled with catalytic/colorimetric gold-ion amplification, this platform produced results within 20 min with a detection limit of 0.92 pg mL

Currently, filter paper assay (FPA) is used to measure the hydrolytic potential of cellulase enzyme mixtures that are used to hydrolyze a range of cellulosic substrates. However, some of the Whatma...

Paper is envisioned as an alternative to plastics in certain applications to overcome the problems associated with the excessive use of plastics. Water and oil repellency is one of the key requirem...

A sonication of graphite in polysaccharide (pullulan, chitosan and alginate) is one of the viable methods for the preparation of few-layer graphene. However, the effect of these adsorbed polysaccharides on the electrical performance of the produced graphene so far is not yet clear. In order to investigate the present effect of pullulan, chitosan and alginate on the electrical characteristic of resulted graphene, we have produced few-layer graphene using bath sonication of graphite in pullulan, chitosan and alginate medium for the application as electrical conductive ink in strain-sensitive. Data from the TEM reveals the appearance of folded few-layer graphene flakes after sonication for 150 min while the XPS data shows that the chitosan-based graphene possesses the highest carbon-oxygen ratio of 7.2 as compared to that of the pullulan and alginate-based graphene. By subjecting the produced graphene as the ink for paper-based strain sensor, we have discovered that the chitosan-graphene has the best resistivity value (1.66 × 10-3 Ω⋅cm) and demonstrate the highest sensitivity towards strain (GF: 18.6). This result interestingly implies the potential of the reported chitosan-based conductive ink as a strain-sensitive material for future food packaging.

A simple and effective ratiometric fluorescence sensor of CdTe QDs/GCNNs for on-site and rapid analysis of Cu2+ has been established by mixing physically CdTe QDs and graphite carbon nitride (GCNNs). Two emissions peaks of CdTe QDs at 572 nm and GCNNs at 436 nm are both excitated at 340 nm. Under a UV lamp, fluorescent of traffic yellow CdTe QDs is linearly quenched by Cu2+ (as the detection signal), while blue GCNNs remains unchanged (as the reference), resulting in a distinguishable color change gradually from pink yellow to blue. The limit of detection (LOD) of this new sensor for Cu2+ is as low as 0.47 ng mL-1 with 1.4 % RSD. The established method has been successfully applied to detection of Cu2+ in various drinks with satisfactory results. Moreover, a paper-based sensor, which has been prepared by soaking cellulose acetate membrane in CdTe QDs/GCNNs sensor solution, has a wide semiquantitative detection range for Cu2+ (0.01 ~ 5.0 μg mL-1 ). It has realized successfully on-site and rapid determination of Cu2+ in red wine without any pretreatment procedure and is of great promotion and application value in determination of Cu2+ in liquid samples.

Cellulose-based material has been increasingly used as a suitable substrate for depositing metal–organic frameworks (MOFs) in recent years. In this work, MOFs (Cu-BTC) were deposited onto carboxymethylated filter paper (CMP) using four different preparation procedures: one-pot, two-step, layer-by-layer-organic (LbL-org), and layer-by-layer-water-organic (LbL-wtr-org). The products (Cu-BTC@CMP) were comparatively characterized by SEM, ATR FT-IR, XRD, and BET specific surface area analyses. The Cu-BTC crystals were immobilized on the CMP surface, where different deposit ratios (1.31% for one-pot, 4.23% for two-step, 31.49% for LbL-org, and 39.38% for LbL-wtr-org, respectively) were obtained when different preparation procedures were used under the precondition of the same chemical dosage and reaction time. The Cu-BTC crystals were found to grow in the main solution rather than on the substrate surface and the layer-by-layer method would contribute to a remarkable quantity of MOFs depositing onto the substrate surface. The crystals on Cu-BTC@CMP surface prepared by LbL-wtr-org procedure presented a much larger particle size and rougher surface compared to those prepared by the LbL-org procedure due to the aqueous solution of copper precursor. Depositing more Cu-BTC onto CMP surface also endowed the composite prepared by LbL-wtr-org procedure with the highest gas adsorption capacity (1.59 × 102 m2/g of BET specific surface area). Hence, the LbL-wtr-org procedure will be an optimal pathway for depositing metal–organic frameworks onto cellulose-based materials with the advantages of saving organic solvents and best gas adsorption ability.

Nano-dielectrics, which were discovered more than 20 years ago, were once considered as promising insulators. Adding or hybridizing inorganic oxides into polymer matrices inevitably results in poor compatibility between multiphase materials and thus results in limited breakdown strength improvement (generally lower than 20%). Therefore, we bypassed the traditional nano-doping method and proposed the direct construction of matrix materials on nanostructures, that is, a ceramic fiber-porous silica composite insulating paper. The breakdown strength of prepared dielectric was remarkably improved by 120.5%. To the best of our knowledge, such a high improvement in electrical performance has not been reported in previous studies.

Purpose To determine the measurement equivalence of computer touch screen assessment (CTSA) and paper based assessment (PBA) of the oral health impact profile (OHIP-14). Patients and Methods A randomized crossover trial was conducted. Sixty participants were randomized to either i) Arm A: completed CTSA then PBA of OHIP-14, or ii) Arm B: PBA and then CTSA of OHIP-14 within the same day. User preference and time taken to complete the assessments were recorded. Agreement between CTSA and PBA was determined using directional difference (DD), absolute difference (AD), and intraclass correlation coefficient (ICC). Results There was no significant difference in CTSA and PBA OHIP-14 scores (P>0.05). The magnitude of the DD in scores between assessment methods was small for overall scores and all domains (

There is a growing interest on recycling of waste fibres as an alternative to landfill disposal. The aim of the study was to investigate the durability and mechanical properties of waste paper–cement composite panels reinforced with varying kenaf fibre content (FC, 2–10%). The panels produced were evaluated for properties including modulus of rupture (MOR) and apparent modulus of elasticity (MOE). The resistance of the panels was tested in the field for both termite damage and fungi decay for a period of 24 weeks. Accelerated decay test was also performed on selected samples. The results showed that the mean MOR ranged from 3.17 MPa for samples with 10% FC to 4.84 MPa for samples with 8% FC. The mean MOE ranged from 248 MPa for samples with 10% FC to 1298.1 MPa for samples with 8% FC. Statistical analysis showed that the effect of the fibre content was significant on the properties evaluated (p

In this work, the mechanical properties of Kraft paper (KP) coated with a coating formulated with recycled polystyrene dissolved in the solvent lime limonene (rEPS/LL) are investigated. These mechanical properties are compared with those of KP coated with three different commercial coatings: oil-based alkyd coating (ALKY), oil-based phenolic coating (PHEN) and water-based acrylic coating (ACRY). The morphology characterization via scanning electron microscopy showed the KP coated with rEPS/LL resembles a layered structure, in which, part of the coating remained on the surface and part of the coating was absorbed by the KP. The KP coated with rEPS/LL exhibited the highest tensile stiffness and compression strength when compared to the uncoated KP and KP coated with commercial coatings. The remarkable compression properties of the KP coated with rEPS/LL coating may be explained by the bending and crushing mechanisms observed during the ring crush test. The excellent mechanical performance of rEPS/LL combined with an environmentally friendly process to obtain recycled EPS using a bio-based solvent presents several advantages for coating applications. These results warrant further research to fully understand the properties of KP coated with rEPS/LL.

A green analytical paper based assay of Cu (II) has been developed using egg white protein as a natural reagent. Either crayon and pencil graphite, or laser engraver may be used to effectively crea...

Cotton is cheap, easily available and widely used as surgical material. Therefore, cotton would be good raw material to design a scaffold for tissue engineering applications. In this work, the gelatin-coated microfibrous paper scaffold was fabricated successfully by a papermaking process. Microfibers-based scaffold could overcome the limitations of nanofibrous material-based scaffold for tissue engineering application. The physicochemical and mechanical properties of the scaffolds were characterized. The results revealed that the gelatin contributed to the enhanced cell attachment and proliferation over the scaffolds, whereas cellulose as a strong backbone in the scaffold to support it for keeping its appearance. Their tensile strength and water absorption capacity were improved, but pore size and porosity were decreased after incorporation of gelatin. Hence, results suggested that fabricated scaffolds have huge prospective as a bioactive, well-designed and economical scaffold stand for tissue engineering application.

The incompatibility of most organic solvents with acetylcholinesterase (AChE) inhibition assay normally limits pesticide extraction efficiency in sample pretreatment, which might cause false negatives in real world sample assessment. Herein, a novel method has been developed for an improved AChE inhibition assay via organic solvent extraction combined spontaneous in situ solvent evaporation on microfluidic paper-based analytical devices. Enzyme pre-immobilization procedure was spared and AChE was added to the system after sampling step until a complete in-situ solvent evaporation process was performed on chip. IC50 levels of the six investigated organophosphate and carbamate pesticides indicated a completely eliminated influence of solvents on AChE behavior with the new method. Most importantly, analytical performances were significantly improved in food sample measurements. Reduction in matrix effect was observed when acetonitrile was adopted for lettuce sample pretreatment instead of water. Studies on different pesticides suggested a remarkably decreased discrimination effect on recoveries from sample pretreatment with the new developed method. The recovery level for phoxim spiked head lettuce samples reached (107.5 ± 14.2) %, in comparison with that of (18.6 ± 1.4) % from water-based extraction. Spiked water and apple juice samples with carbaryl concentration of as low as 0.02 mg L−1 were also successfully recognized with the present method by visual detection. This is the first report on direct sampling of organic extracts for AChE inhibition assay on-chip and it might provide a new perspective for real world sample assessments involving bio-reagents.

Herein we report the first two distance-based microfluidic paper-based analytical devices (μPADs) using fluorescence to quantify aluminum. In addition to their read-by-eye quantification, the devices are simple to fabricate, require no sample pretreatment or preconcentration, and have a shelf life of >5 months. The first device is designed in a “chemometer” format where the length of a fluorescent band linearly responds to an Al(III) concentration. The second device uses a radial design where the fluorescent diameter also linearly responds to an Al(III) concentration. The chemometer device has a detection limit of 2.5 ppm (100 μM) and a linear range from 2 to 54 ppm Al(III) (100 μM–1 mM), R2 = 0.989). The radial device has a detection limit of 0.9 ppm (33 μM) and a linear range from 2 to 24 ppm Al(III) (100–900 μM, R2 = 0.968). The utility of the μPADs were successfully demonstrated by measuring Al(III) in two water effluent samples from the Gold King Mine near Silverton, CO.

There has been an increase in the discovery and usage of sensors for the detection of chemical compounds in the field of analytical chemistry since the last several years. This has led to progressive research in nanotechnology for developing efficient nanomaterials for bio-chemical sensing applications. Thereby, a deft synthesis of silver nanoparticles (Ag NPs) under microwave irradiation was achieved using sodium alginate as a reducing and capping agent in a fast and cost-effective approach. As per the X-ray diffraction analysis, the average particle size of Ag NPs was found to be 10 nm. X-ray photoelectron spectroscpopy analysis showed characteristic peaks at binding energies of 368.10 and 374.11 eV indicating the formation of Ag NPs. The synthesized Ag NPs-alginate composite was further used to develop a paper-based sensor for the detection of H

Biohydrogen and biomethane production via two stage sequencing system from paper mill effluent (PME) was evaluated to enhance its COD reduction. Heat-shock pretreatment of anaerobic sludge at 90 °C for 15 min was chosen to obtain a mixed microbial inoculum for dark fermentative hydrogen production. The effect of initial pH (5, 6 and 7) on the efficiency of hydrogen fermentation at different concentrations of substrate (3, 5 and 7 g-COD/L) was investigated, which the maximum hydrogen yield was obtained at initial pH 5. After that, the effects of substrate concentration (3, 5, 7, 10 and 15 g-COD/L) and fermentation temperature (37 and 55 °C) were investigated on the hydrogen production yield. The efficiency of dark hydrogen fermentation for all substrate concentrations was higher at 55 °C. The hydrogen production was enhanced as substrate concentration increased up to 5 g-COD/L, but then it was reduced, and the optimum hydrogen yield of 38.8 mL H2/g-CODinitial was obtained at substrate concentration of 5 g-COD/L at 55 °C. The highest hydrogen (35.1 mL H2/g-CODinitial) was obtained at 5 g-COD/L and 55 °C and the highest methane (553.8 mL CH4/g-CODinitial) was obtained at 3 g-COD/L and 37 °C. Maximum COD reduction of 88.1% was obtained in two-stage sequencing dark fermentation/anaerobic digestion system at 3 g-COD/L and 37 °C.

A study was undertaken to make greaseproof packaging paper using banana pseudostem fiber. Kraft pulp produced from banana fiber was beaten to the freeness of 60°SR and 70°SR, and handsheets (40 ± 1...

A low-cost, sensitive, and disposable paper-based immunosensor for instrument-free colorimetric detection of a pancreatic cancer biomarker PEAK1 was reported for the first time by capitalizing the catalytic properties of gold nanoparticle in colour dye degradation. This simple signal amplification method enhances the detection sensitivity by about 10 folds.

Binding protein scaffolds, such as rcSso7d, have been investigated for use in diagnostic tests; however, the functional performance of rcSso7d has not yet been studied in comparison to antibodies. Here, we assessed the analyte-binding capabilities of rcSso7d and antibodies on cellulose with samples in buffer and 100% human serum.

The wide spread of smartphones and QR codes for various end-user applications has had an impact beyond traditional fields of use, recently also reaching point-of-care testing (POCT). This work presents the integration of QR code recognition into paper-based analytical devices (PADs) with "distance-based" colorimetric signalling, resulting in semiquantitative readout fully relying on straightforward barcode reader solutions. PADs consist of an array of QR codes arranged in series inside a paperfluidic channel. A mask dye concept has been developed, which enables utilisation of colour changing indicators by initially hiding QR codes. The colour change of the indicator induced by the presence of an analyte of interest results in gradual unmasking of QR codes, which become recognisable by the smartphone barcode reader app. To reproducibly fabricate devices, all fabrication steps were performed by commercial desktop solid ink and inkjet printing. The QR code masking function was optimised by controlling the amount of printed mask dye through adjusting the opacity of printing patterns during the inkjet deposition process. For proof-of-concept, a model assay in the form of colorimetric copper ion (Cu2+) detection in the concentration range of 0.4 mM to 3.2 mM was evaluated. Consistent results independent of the smartphone model and environmental light condition were achieved with a free barcode reader app. To the best of our knowledge, this work is the first demonstration of a semiquantitative assay approach fully relying on QR code readout without digital colour analysis, customised app or hardware modification.

Filtration products containing silver nanoparticles (Ag-NPs) have been used for water purification to provide drinking water for humans. However, it is unclear if differences in water chemistry influence their effectiveness or whether the presence of Ag in the filtrate (drinking water) impacts the gut microbiome. Using water samples differing markedly in chemical properties, we have found that ≥99.89% of E. coli were killed in all cases, regardless of the water chemistry. However, in the first 25 mL of filtration, concentrations of Ag in most of the water samples (0.14–45.2 mg L−1) exceeded the limit for drinking water (0.1 mg L−1), differing depending upon water chemistry. Synchrotron-based X-ray absorption spectroscopy analysis revealed that up to 36% of the Ag in the filter paper was present as AgNO3 and 64% as Ag-NPs, with this AgNO3 likely contributing to the high Ag concentrations in the filtrate. Finally, we also examined the impacts of oral gavage of the Ag-containing filtrate on the mouse gut microbiome. It was found that Ag from the filtrate accumulated mainly in the liver and kidneys. In female mice, we also found that the Ag-containing filtrate increased the relative abundance of Bacteroidetes in the faeces, whilst decreasing that of Firmicutes. Our data indicate that although Ag-NP-containing filter products have excellent antimicrobial properties, the high concentrations of Ag in the filtrate are potentially of concern for the gut microbiome and further work is required in this regard.

Infections caused by foodborne microorganisms are a great threat to the global environment and public healthcare today. Thus, rapid, portable and sensitive assays that can realize the identification of foodborne bacteria are highly desired. In this study, a smart fluorescent and colorimetric dual-readout sensing system has been established for simple and rapid E. coli determination by utilizing the Cu2+-triggered oxidation of o-phenylenediamine (OPD). Initially, Cu2+ can oxidize OPD to OPDox, resulting in an orange-yellow fluorescence and visible pale-yellow color. However, E. coli can effectively reduce Cu2+ into Cu+, inhibiting the Cu2+-triggered oxidation of OPD to OPDox. Consequently, the introduction of E. coli can turn off both the fluorescence and the UV-vis absorbance signals of the OPD-Cu2+ system, illustrating an original mechanism for fluorescent and colorimetric dual-channel detection of E. coli. Moreover, a filter paper-based visual sensor was built and coupled with OPD-Cu2+ solution under the assistance of a UV lamp. The as-prepared sensor can detect E. coli quantitatively with the help of a typical smartphone color-scanning application (APP). Thus, this study offers a valid dual-mode assay for sensitive and on-site visible detection of E. coli, guaranteeing the reliability of the results and is more attractive for practical use. Graphical Abstract Schematic illustration of the smartphone-integrated sensing system for fluorescent and colorimetric dual-channel detection of E. coli based on the Cu2+-OPD system.

The poor barrier properties and hygroscopic nature of cellulosic paper impede the wide application of cellulosic paper as a packaging material. Herein, a polyvinyl alcohol (PVA)-based polymer coating was used to improve the barrier performance of paper through its good ability to form a film. Alkyl ketene dimer (AKD) was used to enhance the water resistance. The effect of the absorptive characteristics of the base paper on the barrier properties was explored, and it was shown that surface-sized base paper provides a better barrier performance than unsized base paper. Nanoclay (Cloisite Na+) was used in the coating formulation to further enhance the barrier performance. The results show that the coating of PVA/AKD/nanoclay dispersion noticeably improved the barrier performance of the paper. The water vapor transmission rate of the base paper was 533 g/m2·day, and it decreased sharply to 1.3 g/m2·day after the application of a double coating because of the complete coverage of the base paper by the PVA-based polymer coating. The coated paper had excellent water resistance owing to its high water contact angle of around 100°. The grease resistance and mechanical properties of the base paper also improved after coating. This work may provide inspiration for improving the barrier properties of packaging paper through the selection of a suitable base paper and coating formulation.

Rising concern about the use of non-permitted colourants, in common food items such as dals and green vegetables sold in Indian markets, have led to a demand for low-cost point-of-use chemical analysis tools. Conventional food-analysis techniques involving tedious sample preparation protocols are not suited for in-field applications. Surface Enhanced Raman Spectroscopy (SERS) is an analytical technique that is well-suited for point-of-use chemical analysis with molecular level detection capability, which can also serve as a quality assurance tool for businesses. Effective and rapid signal collection from a large-area sample within a field-setting using disposable, low-cost SERS substrates is a key challenge in implementing such a solution. Herein, we demonstrate the use of inkjet-printed thin films comprising of robust nanostructured-silver as flexible, paper-based SERS (P-SERS) swabs for the direct detection of Metanil Yellow (MY) from toor dal (yellow split pigeon peas) samples and Malachite Green (MG) from green peas and green chillies. The macroscopic uniformity of these thin-films in combination with a portable Raman spectrometer equipped with orbital raster scanning (ORS™) technology for signal collection results in an unprecedented precision (RSD ∼ 1.6%) upon characterizing samples saturated with Rhodamine-6G (R6G), a standard Raman probe. As several food-cleansing products have appeared in the marketplace, the adulterant removal efficacy of some commercially available ‘washes’ as well as products such as ‘ozoniser’, which was determined by SERS characterization of swabs before and after use, is also reported.

Many organic residues are being wasted since they are not given a comprehensive management; anaerobic digestion is an alternative to reduce the impact of these residues, and to produce biogas. The chapter includes the state of art about biogas and energy production, and later, the analysis of a study case focusing on the use of pulp and paper wastes to produce biogas. The study was carried out through anaerobic digestion at a bench scale using three temperature phases to treat primary and secondary sludge, establishing operational parameters such as temperature, retention time, and organic loadings. Monitoring of volume, methane concentration in the biogas, volatile solids reduction, volatile fatty acids during the process, the performance of the process in function of methane produced per volatile solids removed is calculated. This case study shows that it is feasible to use the sludge from the company’s wastewater treatment plant (WWTP) for the generation of biogas, thus reducing waste management problems.