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Statement of problem Quick response (QR) codes are a fast and efficient technology for linking and accessing identifying information, and their use has been proposed in forensics. The heat resistance and esthetics of denture marking methods (DMMs) have been recommended by the American Dental Association (ADA), but studies on these aspects of printed QR codes are lacking. Purpose The purpose of this study was to determine the optimal printed material with QR codes for implementation as a DMM adjusted to the recommendations of the ADA. Material and methods The behavior of 4 types of paper, bond paper, fiberglass filter paper, ultralong hydroxyapatite nanowire paper, and polyolefin and silica paper with printed QR codes was analyzed. They were exposed to temperatures between 100 °C and 1000 °C in a heat muffle for 1 hour. Each specimen was subjected to both a morphological and a thermogravimetric analysis (TGA) and scanned by using 3 different smartphones. Results The scans were positive for bond paper (33.3%), fiberglass fiber paper (50%), ultralong hydroxyapatite nanowire paper (100%), and polyolefin and silica paper (70.4%). The TGA revealed continuous decomposition curves (average 16.5 minutes at 624 °C). Conclusions Printed QR codes on ultralong hydroxyapatite nanowire paper appear to be suitable as information reservoirs, even surviving incineration, and may be implemented as a DMM conforming to the ADA recommendations.

Bio-based additives received significant attention in pulp and paper properties improvement. For this, the most cited biochemical Cellulose Nano Fibrils (CNFs) and Cationic Starch (CS) were experimentally compared with the most declared synthetic chemical, Cationic Polyacrylamide (CPAM). SEM images showed better paper surface filling by the utilization of the chemicals. The three studied polymers, in solely or combination mechanism, improved mainly bagasse pulp and paper properties compared to the blank sample, except for pulp drainage, which decreased by CNFs to lower volumes presumably due to its intrinsic characteristics. Cationic polymers (CP) compared to CP/CNFs approaches increased pulp retention and drainage but decreased paper density and strengths. The best pulp retention and drainage achieved by CS followed by CPAM, while paper air persistency, density, and strength properties evaluated highest by CP/CNFs followed by CNFs. Generally, CS revealed a more significant improvement in pulp and paper properties than CPAM either with or without CNFs.

Molybdenum sulfide (MoS2) with well-designed porous structure has the potential to be great electrode materials in sodium-ion batteries due to its high theoretical capacity and abundant resource, however, hindered by its intrinsic low conductivity and stability. Herein, MoS2 with 3D macroporous foam structure and high conductivity was obtained through SiO2 templates and integrated with carbon paper (3D F-MoS2/CP). It has showed superior specific capacity (225 mA h g−1, 0.4–3 V) and cycling stability (1000 cycles) at high rate (2000 mA g−1), with a low decay rate (0.033% per cycle) in sodium-ion batteries. The excellent electrochemical performance may originate from its unique integrated structure: 3D MoS2 macropores providing high surface area and abundant transfer channels while carbon paper enhancing the conductivity of MoS2 and avoiding unnecessary side reactions brought by binder addition.

This manuscript aimed to enhance the mechanical, thermal, and ignition properties of bagasse paper when coated with different coatings synthesized from hydroxyethyl cellulose, 1,3-di-p-toluidine-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane, Talc powder, NaHCO3, cellulose nanocrystal. The effect of these coatings on the mechanical properties was studied by measuring elongation, tensile strength, and burst strength. The stages of degradation and ash residue of the measuring specimens were determined using thermal gravimetric analysis (TGA), behind that, the ignition properties as the flame chamber (UL/94), and limiting oxygen index (LOI) was measured according to standards. These tests proved that 1,3-di-p-toluidine-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane has a direct effect on improving the mechanical characteristics and enhancing the ignition properties of the coated specimens compared to uncoated. In this study the physical, mechanical, thermal, and ignition properties of the bagasse paper sheets were enhanced by easy and low-cost method via synthesis of new coatings based on commercially available chemicals in a reasonable cost.

The construction industry had approached a critical limit which led to the increase of cement production. The production of cement would cause a broader environmental implication. Cement production is a major source of carbon dioxide emission. Carbon dioxide gas contributes about 63.33% of global warming since the production of one ton of cement would emit about one ton of carbon dioxide to the environment. To mitigate this issue, the research community has investigated the use of waste materials that possess similar chemical properties with cement content as a material for partial cement replacement. The use of rice husk ash has shown to be a contending candidate in the literature. Therefore, this paper attempts at reviewing the performance of rice husk ash as partial cement replacement. It could be observed from the literature that concrete with 5% up to 15% of rice husk ash showed an equivalent performance to ordinary concrete in compressive, flexural, and tensile strength. Thus, rice husk ash can be used as a material replacement in concrete and reduces pollution that originates from cement production and open burning of rice husk.

A novel paper-based analytical device (PAD) was prepared and applied to determine the xanthine oxidase (XOD) inhibitory activity of Salvia miltiorrhiza extracts. First, polycaprolactone was 3D printed on filter paper and heated to form hydrophobic barriers. Then the modified paper was cut according to the specific design. Necessary reagents including XOD for the colorimetric assay were immobilized on two separate pieces of paper. By simply adding phosphate buffer, the reaction was performed on the double-layer PADs. Quantitative results were obtained by analyzing the color intensity with the specialized device system (including a smartphone, a detection box and sandwich plates). The 3D-printed detection box was small, with a size of 9.0 cm × 7.0 cm × 11.5 cm. Color component G performs well in terms of linearity and detection limits and thus was identified as the index. The reaction conditions were optimized using a definitive screening design. Moreover, a 10 % glycerol solution was found to be a suitable stabilizer. When the stabilizer was added, the activity of XOD could be maintained for at least 15 days under 4 °C or -20 °C storage conditions. The inhibitory activity of Salvia miltiorrhiza extracts was investigated and compared to that of allopurinol. The results obtained with the PADs showed agreement with those obtained with the microplate method. In conclusion, the proposed PAD method is simple, accurate and has potential for point-of-care testing. It also holds promise for use in rapid quality testing of medicinal herbs, intermediate products, and preparations of traditional Chinese medicines.

Tremendous attention has been paid on high efficiency, readily available and stability of electrocatalysts. Herein, we ingenious report a one-step reaction strategy synthesis of CoFe/CP grown on three-dimensional (3D) nanoarray carbon paper (CP) containing non-precious metals for oxygen evolution reaction (OER) with low-cost and unique hierarchical porous structure. This amorphous CoFe/CP hybrid exhibits commendable electrocatalytic performance in the OER process, requiring only overpotential of 278 mV to achieve 10 mAcm−2 in 1.0 M KOH solution and a lower Tafel slope of 49.12 mVdec-1. In addition, this sample shows a long-term durability even at 200 mAcm−2 without obvious decay, which attributes to peculiar multistage graded nano structure and the change of composition at the interface of CP. Therefore, the remarkable OER activity can provide a new strategy to construct potential candidates, which will replace the state-of-the-art precious metals for OER in the future.

As a crucial biomarker for some diseases, the determination of cholesterol in human serum is of great significance for the diagnosis and prevention of these diseases. Hence, a portable cholesterol detection method is necessary for clinical and domestic applications. Here, a portable paper sensor was designed for cholesterol detection by modifying screen-printed electrode (SPE) with nanoporous gold (NPG). To achieve the reliable cholesterol detection, a synergistic strategy was proposed based on the oxidation of cholesterol by cholesterol oxidase (ChOx) and the reduction of oxidation product (H2O2) by NPG. Compared to existing electrochemical sensors, the resulting paper sensor exhibited a wider linear response in a range from 50 μM to 6 mM as well as a higher sensitivity of 32.68 μA mM−1 cm−2 with a lower detection limit of 8.36 μM. Moreover, the portable paper sensor presented strong anti-interference capability and stability in the detection of cholesterol in human serum, and the data detected by the portable paper sensor were consistent with that obtained by an automatic biochemical analyzer. These unique performances confirmed that the proposed paper sensor was a sensitive, reliable, and portable cholesterol detection method, making it a good choice for cholesterol detection.

Graphene-based nanomaterials possess broad applications because of their excellent multi-functional properties. In this work, a facile self-assembling method was presented for preparing one kind of graphene oxide-based paper/hollow microspheres hybrid. It was found that most of the hollow microspheres can strongly anchored on the surface of graphene oxide paper (GOP) by an in-situ scanning electron microscope peeling testing combining with molecular dynamics (MD) simulation. In addition, the uniform distribution of hollow microspheres on the surface of GOP cannot only provide a better surface wettability, but also can effectively improve the interfacial stress-transfer capability between such hybrid and polymer matrix. Our work provides a guidance for the structural designs of graphene-based nanomaterials and broaden their applications.

With the increased awareness of reusing solid wastes for higher sustainability and the concern of water pollution associated with phosphorus over-emission, there are strong interests in developing solid waste based adsorbents for purifying phosphorus-containing wastewater. As a rich calcium resource, paper mill sludge (i.e., a major solid waste from pulping industry) can be used as phosphorus removal adsorbent after calcination. Thus, in this work, a simple and clean thermally treating route has been proposed for preparing calcium-containing biochar from paper mill sludge. The effect of the physicochemical properties of paper mill sludge and its carbonization condition on phosphorus adsorption has been analyzed. Moreover, the influence of some key adsorption parameters, e.g., biochar dosage, initial pH of solution, co-existing anions, initial phosphorus concentration and contact time has also been investigated. The results showed that the phosphorus adsorption data could be fitted well with pseudo-second-order kinetic and Langmuir isothermal models. The calculated maximum adsorption capacity of the as-prepared optimal calcium-containing biochar could reach to 68.49 mg·g−1 at 25 °C. Combined with the characterization results, it can be reasonably inferred that the adsorption process was chemisorption-dominated. Lastly, the application of this spent adsorbent in agriculture field has also been discussed. In brief, this work provided a feasible strategy for converting paper mill solid waste to an environmental functional material (i.e., calcium-rich biochar) for remediation of eutrophic water.

This study optimizes a novel surfactant-assisted green liquor dregs (GLD) pretreatment of paper mill sludge (PMS), both of which are wastes from the kraft pulping industry, using a combined Response Surface Methodology (RSM) design. Optimized conditions give a maximal reducing sugar release of 16.38 g/L. A substantial reduction in heavy metals aluminum, chromium, cobalt, arsenic, lead, and copper after pretreatment illustrates the enhancement of substrate digestibility by reducing toxic elements. Separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) for hydrogen production are assessed. SSF produced a hydrogen yield of 3.72 mL/g, displaying a 36.26% increase from pretreated PMS compared to SHF. These findings provide insights into possible methods of reducing process duration, energy input, and costs incurred with waste disposal within the paper industry. Furthermore, improved hydrogen yield using an SSF process demonstrates the potential beneficiation of pulp and paper GLD and PMS wastes.

Developing efficient and stable non-noble metal oxygen evolution reaction (OER) electrocatalysts for sustainable overall water-splitting is extremely desirable but still a great challenge. Herein, we developed a facile strategy to fabricate Co3O4–CoOOH heterostructure nanosheet arrays with oxygen vacancies grown on carbon paper (Co3O4–CoOOH/CP). Benefiting from the unique 3D architecture, large surface area, synergistic effects between Co3O4, CoOOH and oxygen vacancies, the obtained self-supporting Co3O4–CoOOH/CP presents excellent electrocatalytic OER activity (low overpotentials of 245 and 390 mV at 10 and 100 mA cm−2) and robust long-term stability in alkaline condition. The present strategy provides the opportunities for the future rational design and discovery of high-performance non-noble metal based electrocatalysts for advanced water oxidation and beyond.

Construction sludge frequently has high alkalinity after its generation or during the intermediate treatment process. The aim of this study is to experimentally investigate the potential of combining accelerated carbonation and a paper sludge ash-based stabilizer (PSAS) to neutralize the alkalinity of construction sludge in a short period and to improve its strength for use as a recycled material. The experimental results indicate that the addition of a PSAS significantly granulated the alkaline sludge, and once granulated, the PSAS successfully accelerated the pH neutralization of the alkaline sludge. It was also found that the decrease in dry density ρd and the degree of saturation Sr of the PSAS-treated sludge was able to reduce the period required for the pH neutralization, tN. The decrease in ρd is thought to allow fresh CO2 gas to penetrate the specimen more easily. However, if Sr is below a certain limit, it does not strongly facilitate the reduction of tN. This implies that pH neutralization cannot be accelerated when the amount of water in the sludge is below a certain level. Moreover, it was found that mean particle diameter D50 also affected tN. The strength development of the PSAS-treated sludge was evaluated using a series of cone index tests. It was found that the strength of the alkaline sludge without the PSAS was significantly decreased by accelerated carbonation, but was significantly increased even after accelerated carbonation when the PSAS was present. Due to the porosities of the remaining PS ash particles, most of the contribution of the water absorption and retention performance of the PSAS to the strength development of the PSAS-treated sludge was secured after accelerated carbonation. In addition, the granulated particles of the PSAS-treated sludge retained their granular shape to some extent. Therefore, it is presumed that the friction and interlocking of the particles did not decrease significantly. It was also found that, after carbonation, the qc of the PSAS-treated sludge increased more rapidly than that of the alkaline sludge without the PSAS. A further detailed examination of the test results showed that under air-curing conditions, the qc of the treated sludge with accelerated carbonation increased relatively gradually compared to that of the treated sludge without accelerated carbonation.

Funding Information: The financial support of the Austrian Federal Ministry of Digital and Economic Affairs and the National Foundation for Research, Technology and Development , Austria, is gratefully acknowledged. We also thank the industrial partners Mondi, Canon Production Printing, Kelheim Fibres, and SIG Combibloc for their support. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Hydrophobization of cellulosic materials and particularly paper products is a commonly used procedure to render papers more resistant to water and moisture. Here, we explore the hydrophobization of unsized paper sheets via the gas phase. We employed three different compounds, namely palmitoyl chloride (PCl), trifluoroacetic anhydride/acetic anhydride (TFAA/Ac2O)) and hexamethyldisilazane (HMDS) which were vaporized and allowed to react with the paper sheets via the gas phase. All routes yielded hydrophobic papers with static water contact angles far above 90° and indicated the formation of covalent bonds. The PCl and TFAA approach negatively impacted the mechanical and optical properties of the paper leading to a decrease in tensile strength and yellowing of the sheets. The HMDS modified papers did not exhibit any differences regarding relevant paper technological parameters (mechanical properties, optical properties, porosity) compared to the non-modified sheets. XPS studies revealed that the HMDS modified samples have a rather low silicon content, pointing at the formation of submonolayers of trimethylsilyl groups on the fiber surfaces in the paper network. This was further investigated by penetration dynamic analysis using ultrasonication, which revealed that the whole fiber network has been homogeneously modified with the silyl groups and not only the very outer surface as for the PCl and the TFAA modified papers. This procedure yields a possibility to study the influence of hydrophobicity on paper sheets and their network properties without changing structural and mechanical paper parameters.

Cellulose triacetate (CTA) forward osmosis (FO) membrane from Hydration Technology Innovation (HTI), USA was tested in a locally fabricated FO system to concentrate synthetic and pulp and paper mill wastewater. The industry is among the 17 most polluted industries with intensive water consumption and wastewater generation (MoEFCC, Government of India). The CTA membrane was studied with deionized water as feed solution and 1 M NaCl as draw solution, which resulted into water flux of 5.8 L/m2h and reverse salt flux of 0.2 g/L. A concentration stepping method was used to determine the critical draw concentration with lignin solution as the model feed. There was no deviation in flux between the baseline (deionized water feed) and the lignin solution up to 1.5 M NaCl, but a marginal deviation (8% and 21% respectively at 2 M and 3 M) was seen thereafter. The average water flux after 24 h FO study with synthetic wastewater as feed solution (draw solution 2 M NaCl) was 8 L/m2h, and 80% water recovery. Similar study with pulp and paper wastewater as feed solution (draw solution of 1.5 M NaCl) was 5.4 L/m2h was with 62% water recovery. Lignin and COD rejection in pulp and paper mill wastewater was 90% and 64% respectively. The preliminary results indicate that FO is promising for water and lignin recovery from waste streams.

Paper and pulp mills generate substantial quantities of cellulose-rich sludge materials that are disposed in landfills at a large scale. For sustainability purposes, sludge materials can be bioprocessed to produce renewable fuels and useful chemicals. The enzymatic hydrolysis of cellulose is the process bottleneck that affects the conversion economics directly by using zero-cost raw materials. In order to study and optimize the process, the characteristics of the sludge raw materials should be first evaluated. In this work, sludge samples were obtained from paper mills located at different locations in Wisconsin and Minnesota. Part of the sludge samples was washed (de-ashed) with hydrochloric acid while the other part remained unwashed. The samples were subjected to multiple spectroscopic analyses techniques to evaluate the morphological properties of cellulose fibers and to estimate the total structural carbohydrate content. The results showed that the de-ashing process changed some fiber characteristics and cellulose crystallinity structure in all sludge samples. Sludge sample A (obtained from Kraft pulp and recycled paper mill region) showed a high percentage of fiber, with crystalline cellulose, compared to the other two sludge samples suggesting that sludge A is a valuable source to make value-added products. Aspen Plus mass and energy calculations performed in view of the ‘zero’ cost and the reliable supply of sludge raw materials producing 2 mol H2/mol glucose. Moreover, the results showed that extracting crystalline cellulose from these sludge samples is more profitable than crystalline cellulose made from the other lignocellulosic feedstocks. The results reported here showed that the utilization of these sludge materials would be an economically attractive and promising alternative for the production of hydrogen.

Biodiesel, as a green fuel, acts as a potential candidate to supplement conventional fossil fuels. This research study targets green environment (using biodiesel) and clean environment (reduce wastewater) by producing biodiesel through oleaginous biomasses (Yarrowia lipolytica, Metschnikowia pulcherrima and Lipomyces starkeyi) grown on pulp and paper industrial wastewater. Batch culture studies were explored for the potential feedstock of the oleaginous organism by the synthesis of single cell oil and fatty acid methyl ester (FAME) yield. Response surface methodology (RSM) was used to design the optimal experimental matrix and identify the optimal process conditions that enhance the FAME yield. To determine the inherent characteristics of the growth of oleaginous biomasses on the industrial wastewater, a data-driven adaptive neuro-fuzzy inference system (ANFIS) is implemented. Y. lipolytica strain cultured shown high biomass concentration of 32.36 g/l with biomass productivity of 5.39 g/l/d was considered for further scale-up for the transesterification process. Results indicated that the maximum yield of 0.48 (g-biodiesel/g-lipid) was obtained under the 2.5 g of lipid dosage with 0.02 g/ml of catalyst concentration by constant stirring at 70 °C. The optimum conditions to achieve maximum FAME yield of 1.154 g/g was obtained at 2.485 g, 70.87 °C and 0.021 g/ml for lipid dosage, temperature and catalyst concentrations, respectively.

Wastewater containing heavy metal ions is considered as the serious environmental problem in human society. Adsorption as the widely used method plays an important role in wastewater treatment, which is based on the physical interaction between metal ions and sorbents. Drumsticks are reported to have efficient adsorbing property. It has been found that Moringa causes alteration in testosterone levels, preventing testicular damage and hence is capable of protecting against the toxic effect of hazardous material. Based on this phenomenon of adsorption by Moringa species, we are trying to remove heavy metals from aqueous sample. The bio sorption of heavy metals by non-living biomass of plant origin is an innovative and alternative technology for the removal of the pollutants from aqueous solution and offers several advantages such as low-cost bio sorbents, high efficiency, minimization of chemical and/or biological sludge, and regeneration of the bio sorbent. Moringa oleifera (drumsticks) has a number of advantages including low cost, biodegradable sludge production and lower sludge volume, and also it does not affect the pH of the water. Apart from turbidity removal, Moringa oleifera seeds also possess antimicrobial properties. Amount of adsorption is considerably larger when activated charcoal is used. Thus, this work reports preparation of activated charcoal from drumsticks seeds and fibres. These are generally part of kitchen waste; thus, its preparation and utilisation for heavy metal toxicity not only controls water pollution but also help in reduction of kitchen waste. It will serve as an effective, cheap and robust and green tool for toxicity control. The paper reports the removal of heavy metal (Pb, Ni, Cd, As in this study) by application of prepared activated charcoal tablets via MATLAB assisted paper based sensors. These tablets will surely serve as point-of- care devices for removal of heavy metal toxicity.

Cyanide ( CN - ) is a deleterious chemical and can cause serious health effects upon exposure even at low concentrations. Different sensors have been developed to monitor cyanide in water, which, however, suffers from complex mechanisms and high-cost. Curcuma longa or turmeric is a commercially available natural dye (usually in powder form) used as medicine. The phenolic substance curcumin is responsible for its yellow color and is capable of sensing environmentally significant analytes such as CN - . In this study, a colorimetric sensor for cyanide in aqueous solution was fabricated by the immobilization of crude curcumin on ordinary filter paper. The curcumin was extracted from locally available turmeric powder using a simple extraction method. Its successful integration in the filter paper was validated by FT-IR spectroscopy. UV–Vis analysis showed that the curcumin-based paper sensor was sensitive to CN - (down to 5.0 ppm), producing a visual change from yellow to dark red. The fabricated sensor also demonstrated high selectivity towards CN - in the presence of N a + , K + , and F - . Its response time was found to be inversely proportional to the concentration of the CN - in the solution. Assessment of reusability revealed that the sensor was reusable for up 8 cycles before significant changes in colorimetric response were observed. Importantly, the fabricated sensor exhibited applicability for actual cyanide monitoring in real water samples.

Food safety is always one of the most important issues for human being. With the variety of food, it is required to develop rapid, low-cost and convenient detection techniques for food safety. As a representative, paper-based detection techniques have developed rapidly from simple test papers to various microfluidic paper-based devices. The paper-based analytical devices combining paper platform with a variety of advanced analytical methods have shown great application prospects for rapid testing of food safety. In this review, the surface functionalization and modification of paper are introduced. Then, the construction and development of various detection techniques are discussed, including colorimetric analysis, fluorescent analysis, electrochemical analysis, surface enhanced Raman spectroscopic analysis, and multimethods on paper-based platforms for the application in rapid detection for food safety. Finally, the prospects and future challenges of rapid detection techniques in food safety are also discussed.

Recently, the interest in active packaging utilization has increased with population growth, food demand and new consumer trend like food delivery services. This new system, however, requires the use of additives to extend the food product quality and safety as well as in maintaining the shelf-life. This study was to prepare the antimicrobial paper from I. cylindrica coated anionic nanocellulose crosslinked cationic to create a system with the ability to actively control microbe growth in the packaging materials. The process involved pulping of I. cylindrica using semi-chemical and soda chemical method. The antimicrobial paper was prepared by printing the pulp suspension in 60 g/m2 grammage in mold followed by the spray of anionic nanocellulose and subsequent soaking of the paper in cationic solution. The results showed the I. cylindrica paper coated anionic nanocellulose crosslinked with H+ and Al3+ cations were successfully produced. The paper produced was also observed to have antimicrobial activity against Gram-negative of E. coli and S. typhi as well as Gram-positive of S. aureus and B. subtilis bacteria. Furthermore, the best coating method was found on antimicrobial paper coated anionic nanocellulose crosslinked Al3+ as evidenced by smoother and compact surface structure.

There is a pressing need around the world to develop novel functional biodegradable materials to separate oil/water mixtures and emulsions completely. Recently, superhydrophilicity and underwater superoleophobicity materials have been attracted attention due to their high efficiency in oil/water separation. However, it is still a challenge to prepare materials that combine oil/water separation and water purification in an environment-friendly way. In this work, biodegradable starch-based nanospheres (SNPs) coated filter paper was prepared in a low-cost, simple, and environmentally friendly manner. The SNPs coating could not only help to change the wettability of the substrate material but also build the hierarchical micro and nano structures which are conducive to separation and purification process. After modification by coating SNPs, the filter paper exhibited excellent performance in a wide range of oil/water mixtures or emulsions separation and the wettability of the filter paper could be regulated by adjusting the pH value. The modified filter paper presented good recyclability after several separation process. Furthermore, the as-prepared filter paper could also remove water-soluble contaminants during the oil/water separation process, thus realizing to combine separation and purification process in one single step. This biodegradable starch-based separating material with good separation performance, stability and recyclability has significant application potential in practical separation and purification process.

Paper mulberry, a fast-growing and vigorous plant, is a potential substrate for producing lignocellulosic bioethanol and an important renewable alternative to fossil fuels. In order to improve the economic feasibility of ethanol production from paper mulberry, H3PO4/H2O2 pretreatment was selected as the most suitable pretreatment method that could produce the highest glucose concentration (131 g/L) compared with other pretreatments (73.2–89.3 g/L) at high solid loading. Whereafter, the final solid loading of H3PO4/H2O2 pretreatment was significantly increased to 40% (w/v) without any decrease in the final glucose concentration. Finally, a novel Fed-nonisothermal-simultaneous saccharification and fermentation was constructed using H3PO4/H2O2 pretreated paper mulberry, which bypassed the inhibition caused by paper mulberry solid and high temperature on the traditional simultaneous saccharification and fermentation, improving ethanol concentration (63.9 g/L), ethanol productivity (1.33 g/L/h) and ethanol yield (0.160 g/g-biomass) by 30.4%, 30.4% and 30.1%, respectively, compared to those obtained from SSF (simultaneous saccharification and fermentation) process. Thus, we have opened up a novel way to produce ethanol or other biofuels using the paper mulberry as an outstanding alternative substrate.

Starch and derivatives thereof have proven their usefulness in paper coating processes. Among these derivatives, cationic starch has been widely used in the paper industry as a flocculation, dispersion and ink fixing agent. In another context, nanoscale cellulosic materials have been shown to improve the strength, retention of fillers, the barrier properties of packaging paper products, and printing qualities. This review summarizes the recent studies on the general components used in paper coating, describes the conventional and alternative synthetic processes of cationic starches and nanocellulose, and deals with their current and potential applications in papermaking, focusing primarily on surface treatments. Moreover, environmental applications have been considered to expand the understanding and usefulness of these materials. Further research on modified polysaccharides is encouraged to replace, in a feasible way, petro-based components of coating formulations, and to provide paper surfaces with new properties.

Paper wastes form the major biodegradable fraction of the municipal solid waste. One of the best ways to treat paper wastes is using them as a feedstock for biomethane production through anaerobic digestion (AD). However, the AD characteristics, kinetics, and energy potential of different types of paper wastes are not clear. In this study, four kinds of typical paper wastes including corrugated board (CB), office paper (OP), tissue paper (TP), and magazine paper (MP) were used as feedstocks to produce biomethane at different volatile solids (VS) organic loading (OL). TP had a high cellulose content and showed high biomethane potential, while the lowest was obtained by CB, possibly due to its high lignin content. Kinetic analysis showed that Cone and modified Gompertz model could fit the biomethane production process well. Energy potential analysis revealed that biomethane yield, electric generating efficiency, and electricity price were the principal factors accounting for the profitability of biomethane production project treating paper wastes. Overall, paper wastes could be a promising feedstock for biomethane production, because paper wastes not only had high biomethane yield and biodegradability that exceeded many kinds of organic wastes but also could be continuously supplied for AD plants without the influence of seasonal changes.

This study focuses on the mineral carbonation to capture CO2 using an alkaline industrial waste, the grits, formed during the kraft pulp production process. An indirect mineral carbonation route was adopted, composed by two steps: first the extraction of calcium from the grits and second the precipitation of calcium carbonate. Firstly, four solvents were analyzed (HNO3, CH3COOH, NaOH and NH4Cl). Only HNO3 and CH3COOH have shown significant extraction efficiencies of 79.4 and 73.2 %, respectively, after 2 h at 30 °C. Kinetic tests demonstrated that equilibrium conditions are reached after 60 min. Since the nitric acid is a corrosive acid and with high associated costs, the acetic acid was selected for the dissolution of grits and extraction of calcium. The optimal conditions determined were an acetic acid concentration of 2 M, solid/liquid ratio of 30 g/L and temperature of 45 °C with an efficiency approximately of 77 %. In the second step, carbonation experiments were performed contacting the Ca-rich liquor, obtained from the extraction step, with a flux of pure CO2 gaseous in a stainless inox reactor. The optimal conditions determined were 30 °C and 30 bar, reaching a carbonation efficiency of 74 %, corresponding a CO2 sequestration capacity of 460 kg CO2/ton of grits.

Competitive immunoassays comprise the standard means of detecting small molecules. However, conventional methods using microwells are difficult to apply during point-of-care tests (POCT) because they require complicated handling and are time consuming. Although paper-based analytical devices (PAD) have received considerable focus because of their rapid and straightforward operation, only a few devices have been proposed for competitive immunoassays. Herein, we describe a novel universal PAD format with a 3-dimensional configuration for competitive immunoassays that rapidly and sensitively detects small molecules. The proposed device comprised a layered structure with uniform color formation and high capture efficiency between antigen and antibody that results in rapid and reproducible results. The device rapidly (90 s) assayed biotin as a model target, with a limit of detection (LOD) of 5.08 ng mL−1, and detected progesterone with an LOD of 84 pg mL−1 within 5 min. Moreover, sample volumes and reagent consumption rates were minimized. Thus, our device could be applied to competitive immunoassays of various small molecules in POCT.

Photocatalytic materials have been widely used to remove dyes from printing and dyeing wastewater. However, difficulty in recycling of photocatalysts is the great concern in the real catalytic applications, which significantly raises the application cost. This study developed a low-cost catalyst by loading magnetic Ni onto filter paper (FP) via an easy going in-situ reaction. The characterization results displayed that the Ni particles were uniformly anchored onto the FP. The Ni@FP material presented a strong magnetic ability which was evidenced by a saturation magnetization (Ms) of 5.014 emu·g−1, a remanent magnetization (Mr) of 2.067 emu·g−1 and a coercivity (Hc) of 133.868 Oe. Meanwhile, the magnetic Ni@FP material displayed a recyclable advantage in photocatalytic degradation of methyl orange (MO) via an external magnetic field. There existed an optimal photocatalytic degradation rate of 93.40% within 5 min when MO concentration was 15 mg·L−1 at pH 8.0. Three cycle experiments confirmed that the Ni@FP possessed a satisfied stability and recycling ability. Moreover, the Ni@FP material presented a strong antibacterial activity which can prevent it from being contaminated by microorganisms. The versatility of the newly proposed photocatalyst in this study demonstrated its great application prospect in dyeing wastewater treatment.

Made available in DSpace on 2021-06-25T10:45:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Lactose (LAC) is a disaccharide - major sugar, present in milk and dairy products. LAC content is an important indicator of milk quality and abnormalities in food industries, as well as in human and animal health. The present study reports the development of an innovative imprinted voltammetric sensor for sensitive detection of LAC. The sensor was constructed using electropolymerized pyrrole (Py) molecularly imprinted polymer (MIP) on graphite paper electrode (PE). The MIP film was constructed through the electrosynthesis of polypyrrole (PPy) in the presence of LAC (template molecule) on PE (PPy/PE). To optimize the detection conditions, several factors affecting the PPy/PE sensor performance were assessed by multivariate methods (Plackett–Burman design and central composite design). Under optimized conditions, the proposed analytical method was applied for LAC detection in whole and LAC-free milks, where it demonstrated high sensitivity and selectivity, with two dynamic linear ranges of concentration (1.0–10 nmol L−1 and 25–125 nmol L−1) and a detection limit of 0.88 nmol L−1. The MIP sensor showed selective molecular recognition for LAC in the presence of structurally related molecules. The proposed PPy/PE sensor exhibited good stability, as well as excellent reproducibility and repeatability. Based on the results obtained, the PPy/PE is found to be highly promising for sensitive detection of LAC. Analytical Chemistry Department Institute of Chemistry São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Institute of Exact and Natural Sciences of Pontal Federal University of Uberlandia, 1600 20 St., Ituiutaba, Minas Gerais State Bioenergy Research Institute (IPBEN) São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Analytical Chemistry Department Institute of Chemistry São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Bioenergy Research Institute (IPBEN) São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State FAPESP: 2017/25329–6 FAPESP: 2018/12131–6 FAPESP: 2019/13818–8 CNPq: 408783/2018–4 CNPq: 443315/2014–0 CNPq: 447668/2014–5 CAPES: 88887.368610/2019–00 FAPEMIG: APQ-02078-15 FAPEMIG: APQ-02905-15

SnO2 nanoparticles @ carbon nanoparticles (SnO2@carbon NPs) were synthesized by a facile route using SnCl2·2H2O and filter paper as precursors for lithium ion battery. The different sized nanoparticles of SnO2@carbon NPs were prepared at different temperatures (400, 450 and 500 °C). From the powder X-ray diffraction study the various size of prepared nanoparticles at different temperatures were found to be 16.5 nm (400 °C), 28.5 nm (450 °C), and 35.6 nm (500 °C). Scanning electron microscope (SEM) study reveals the particle nature of synthesized SnO2@carbon NPs. The presence of individual constituents such as Sn, O and C was confirmed by EDAX analysis. TG/DTA studies give assurance of the presence of carbon nanoparticles. FT-Raman spectral study also confirmed the phase and structure of SnO2 nanoparticles. The band gaps of SnO2@carbon NPs prepared at different temperatures (400, 450 and 500) were found to be 3.64 eV, 3.39 eV, and 3.17 eV, respectively by a UV–Vis spectral study. The capacity of SnO2@ carbon NPs prepared at 500 °C was found to be showing better electrochemical properties.

There is growing demand for simple to operate, sensitive, on-site quantitative assays to investigate concentrations of drug molecules in pharmaceutical preparations for quality assurance. Here, we report on the development of two colorimetric analysis methods for the study the antibiotic doxycycline hyclate (DOX) and the nasal decongestant oxymetazoline hydrochloride (OXY), in solution as well as in their respective formulations. We compare a UV/vis spectrophotometry method with a color change recorded on a microfluidic paper-based analytical device (μPAD). Detection is based on the pharmaceutical compounds coupling with diazotized 4-aminoacetophenone (DAAP) under alkaline conditions to produce colored azo-dye products. These azo-compounds were monitored by absorbance at 425 nm for DOX and 521 nm for OXY, with linear calibration graphs in the concentration range of 0.5–35 mg L−1 (DOX) and 1.0–40 mg L−1 (OXY) and limits of detection of 0.24 mg L−1 (DOX) and 0.32 mg L−1 (OXY). For the μPAD method, color intensity was measured from photographs and a linear increase was observed at concentrations from above approximately 15 mg L−1 for both compounds and up to 35 mg L−1 for DOX and 40 mg L−1 for OXY. The developed methods were also applied to the formulated pharmaceuticals and no interference was found from the excipient. Thus, the paper-based device provides an inexpensive, simple alternative approach for use outside centralized laboratories with semi-quantitative capability.

Paper-based colorimetric sensor array has attracted extensive attention due to its low-cost, easy-operation, powerful discrimination, good selectivity, rapid response and versatility. It combines the advantages of paper-based analytical devices and colorimetric sensor array, and extends its application fields in analytical chemistry. This review described the recent progress in paper-based colorimetric sensor array and summarized its applications in biomedicine, environmental and food safety. Moreover, the sensing materials, characteristics and performances of different paper-based colorimetric sensor arrays were investigated. The prospects of future research for the paper-based colorimetric sensor array were discussed.

In this work, we prepared novel cellulosic paper by incorporating tannin into the kraft pulp for potential application in active food packaging. The kraft pulp fibers were firstly periodate oxidized to obtain the dialdehyde cellulosic fibers, and then reacted with varied dosages of tannin to incorporate them into the fibers by covalent bondings between aldehyde groups on cellulose and active hydrogen on tannin. Handsheets were prepared using the tannin incorporated fibers through papermaking process and the properties were characterized. The percentage of tannin in the paper increased with the increase of the tannin dosage. FT-IR spectra confirmed the successful incorporation of tannin into the cellulosic fibers. It was found that paper after incorporation of tannin turned to be surface hydrophobic with contact angles higher than 90°, which may probably due to the covalent bonds between tannin and cellulose. The handsheets show high antioxidative and UV-shielding properties, which both increased with the increase of the tannin percentage in the paper. Water vapor transmission rate (WVTR) decreased after the incorporation of tannin, and this could facilitate its application in food packaging. The breaking length of tannin incorporated paper decreased insignificantly, less than 10% with the tannin percentage as high as 45%.

A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation.

Simultaneous enhancement in water flux and removal efficiency during the filtration process remains a big challenge for separation membranes. The porous structure of the filter paper can provide many channels for water transportation, but the separation performance is generally poor. The purpose of this study is to develop a new kind of filter paper consisting of ultralong hydroxyapatite (HAP) nanowires, cellulose fibers (CFs) and double metal oxide (LDO) nanosheets, and to achieve the simultaneous enhancement of both water flux and removal efficiency for high-performance dye separation. In this work, a novel kind of LDO/HAP/CF nanocomposite filter paper consisting of ultralong HAP nanowires and CFs and LDO nanosheets has been developed for rapid water filtration and highly efficient dye adsorption. Positively charged LDO nanosheets can adsorb on the surface of negatively charged ultralong HAP nanowires and embed in the porous networked structure of the LDO/HAP/CF nanocomposite filter paper, which can provide a porous structure for rapid water transportation and can adjust the pore size of the nanocomposite filter paper. As a result, the pure water flux of the LDO/HAP/CF nanocomposite filter paper can be adjusted. The optimized pure water flux of the LDO/HAP/CF nanocomposite filter paper can reach 783.6 L m-2 h-1 bar-1, which is 1.51 times that of the HAP/CF filter paper without LDO nanosheets (518.6 L m-2 h-1 bar-1). More importantly, the adsorption capacity of LDO nanosheets is high for dye molecules, the rejection percentage of Congo red (CR) by the as-prepared HAP/CF filter paper is only 59.8%, and its water flux is 534.7 L m-2 h-1 bar-1. The optimized rejection percentage and water flux of the LDO/HAP/CF nanocomposite filter paper for CR are significantly enhanced (98.3% and 736.8 L m-2 h-1 bar-1, respectively) compared to those of the HAP/CF filter paper. The size of LDO nanosheets has a significant effect on the water flux and dye rejection percentage of the LDO/HAP/CF nanocomposite filter paper. The as-prepared LDO/HAP/CF nanocomposite filter paper is promising for the applications in highly efficient purification of wastewater containing dye molecules.

Inorganic salt modified paper substrates were developed and utilized in microfluidic paper based sampling coupled with potentiometric ion sensors for the determination of heavy metals, such as Cd2+ and Pb2+. The application of paper based sampling without any paper substrate pre-treatment were characterized with super Nernstian response, while the paper substrates with inorganic salt pre-treatment were characterized with standard Nernstian response. The application of inorganic salt modified paper substrates was found advantageous when the cation of the salt in the conditioning solution was the same as the primary cations of the ion-selective electrodes (ISEs). A relatively high concentration of inorganic salts during pre-treatment of the paper substrates, namely Cd(NO3)2 or Pb(NO3)2 with subsequent measurement of cadmium(II) and lead(II), by Cd2+- and Pb2+-ISEs, respectively was needed to sustain Nernstian response of sensors. It was also found that paper substrates facilitate sorption of metal ions onto the paper substrates, with stronger binding strength given to Pb2+ over Cd2+. Moreover, the metal-paper interactions suggest concentration dependent sorption-desorption of metal ion, which can have direct limitations of the use of paper based analytics for the determination of low analyte concentration of heavy metals. Nanyang Technological University The authors would like to thank NTU-India Connect Research Internship Program for financial support of Ms Tharini Saravana Sundaram from Coimbatore Institute of Technology, India.

Serish (Eremurus) paste, made of Eremurus genus roots, is a strongly adherent substance which had traditionally been used for book binding and paper restoration in Iran for centuries. The proper pH of Serish and its quality of being reversible after long times has made it a good choice in restoring paper. However, it leaves yellow-brown stains on paper due to its own color, which had negatively affected conservator's desire to make use of this adhesive. Therefore the present study was intended to investigate the process of eliminating color from Serish, as a way of improving its quality for paper restoration. The study adopted solvent extraction method to eliminate color from Serish adherent polysaccharide. Extracted adhesives were coated on paper. Humid-thermal accelerated aging was carried out to investigate the effects of adhesives on pH, color change, tensile strength and cellulose structure of papers. It was found that stabilizing enzyme, using 70% boiling ethanol before extracting adhesive, is an effective method to inhibit enzyme operation and prevent creating new chromophores through enzymatic molecules degradation. This approach, on one hand, is useful in removing color and on the other hand proves effective in increasing pH of adhesives. Furthermore, it leads neither to paper acidification nor to damaging polymeric structure of paper after accelerated aging. The results confirmed that the adhesive extracted from the enzymatic stabilized roots by ethanol provides appropriate pH and color; it also improves the tensile strength of paper and yields more desirable results for conservation of paper-based documents, compared to the other examined samples.

This work presents an unconventional use of capacitively coupled contactless conductivity detector (C4D) for detection of gas absorption by moist paper with potential application for chemical analysis. To be suitable for measuring conductivity of moist paper absorbent, the C4D sensor was therefore designed in planar configuration. A layer of dry filter paper, only 20 mm × 25 mm in size, was placed on the C4D sensor and the device installed inside a specifically designed vaporization chamber. A vial (16 mm i.d., 8 mm high) containing a 150-μL solution of sodium bicarbonate was placed alongside. The filter paper was loaded with 110 μL of deionized water through an injection hole in the cover lid. A 100-μL aliquot of 2 M hydrochloric acid solution was directly dispensed into the vial through a second hole in the lid to generate CO2 gas from the bicarbonate solution. It was observed that the C4D sensor gave real-time response that corresponded to the absorption of the gas and subsequent production of H+ and HCO3− in the moist paper. The monitored signal reached a constant value at 160 s after the addition of the acid. Chemistry of the absorption process and equivalent circuit for the C4D are proposed. Direct measurement of cement powder was chosen to demonstrate the potential use of this device for quantifying the CaCO3 content of the cement. The calibration curve for 0.5–3 mg CaCO3 was linear for signals recorded at 160 s: Vdc = (0.172 ± 0.005) · (mg CaCO3) + (0.016 ± 0.009), with coefficient of determination of 0.9965. Linear calibrations were also observed when the signals were monitored at various time less than 160 s. The limit of quantitation (3 SD of intercept/slope) was 0.17 mg CaCO3. The method provided acceptable precision with %RSD of 4.6 (2 mg CaCO3, n = 10).

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. The enhancement of fingermarks on thermal paper can be challenging due to background staining caused by polar solvents used in fingermark enhancement techniques such as ninhydrin. This study explored a commercial one-step superglue fuming process, Lumicyano™, and Vacuum Metal Deposition (VMD) to develop fingermarks on this substrate and overcome this issue. Different sequential treatments involving Lumicyano™ and a combination of VMD methods were investigated with varying degrees of success with some sequences being highly sensitive. The VMD processes, however, were observed to generally be more effective at enhancing marks, whereas Lumicyano™ provided little or no benefit on this paper type. The results indicate that Lumicyano™ is only beneficial as a pre-treatment when the entire sequence of gold/zinc and silver/zinc is taken to completion. The gold/zinc and silver/zinc VMD processes were optimised on five different thermal papers, and the optimised techniques were then directly compared to determine which was more successful on each thermal paper type as a single treatment.

Point-of-care (POC) detection is crucial in clinical diagnosis in order to provide timely and specific treatment. Combining polyamidoamine (PAMAM) dendrimer, p-phenylene diisothiocyanate (PDITC) and superparamagnetic beads, a novel method to activate the surface of filter paper to bind DNA molecules has been developed. The method is based on the primary amination of the filter paper surface with PAMAM dendrimer, followed by generation of isothiocyanate groups via PDITC, and subsequent repetition of these two steps. Different parameters of the process have been optimized, including probe printing, preparation of target DNAs and detection. The result shows that, due to the highly porous structure of filter paper, high amounts of printed probes, target DNAs and magnetic beads can provide high signal intensities in the detection area via probe/target duplex formation. This method is suitable for rapid, specific and cost-efficient DNA detection on cellulose filter paper. It can be used as a POC device, in particular for diagnosis and treatment management of infectious diseases and identification of antimicrobial drug resistance genes.

A novel all-in-one paper-based sampling concept for mass spectrometric bottom-up protein analysis is here demonstrated in a chip format integrating instant immunocapture, protein reduction, - alkylation and tryptic digestion all in-device. Conventional laboratory grade filter paper was coated with the polymer 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (pHEMA-VDM) with a subsequent covalent immobilization of the monoclonal antibody E27 targeting the biomarker human chorionic gonadotropin (hCG). In-device protein reduction and alkylation was optimized with regards to reagent concentration and reaction pH. The sampling concept showed a high degree of performance between 10 and 1000 ng/mL (R2 > 0.99) by a five-point calibration curve sampled with hCG spiked to human serum samples and freshly collected whole blood samples, respectively. LOD (experimentally obtained at 100 pg/mL (2.64 pM/0.9 IU/L)) was demonstrated to be up to ten times lower with more than six times faster sample preparation than what has previously been reported for on-paper analysis of hCG in human serum samples.

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10–500 μg mL−1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL−1, respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL−1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.

The present study delineates the preparation, characterization, and application of (3-Aminopropyl)triethoxysilane (APTES)/Caprine liver-derived extracellular matrix (CLECM) coated paper matrix for cell delivery. Here, we exploited positively charged surface of the paper matrix (as imparted by APTES derivatization) to improve the biological responses of the cells. Our results demonstrated that the functionalized paper matrixes favored the adhesion, growth, and proliferation of multiple cell types including normal, transformed, cancerous, and stem cells as compared to the pristine paper matrix. Upon implantation into the mice model, the developed paper matrix supported infiltration of the host cells and vasculature without showing any evidence of significant systemic toxicity. Moreover, the cells cultured on the paper matrix, when delivered to the CAM and mouse models, showed an enhanced vascular network around the substrate, thereby confirming its potential to deliver the cells in vivo. Together, the study confirms that the reported paper-based platform is easy to fabricate, cheap, portable and could efficiently be applied to cell delivery applications for either tissue repair or the development of humanized animal model.

Paper based assays are paving the way to automated, simplified, robust and cost-effective point of care testing (POCT). We propose a method for fabricating three dimensional (3D) microfluidic paper based analytical devices (μPADs) via combining thin adhesive films and paper folding, which avoids the use of cellulose powders and the complex folding sequence and simultaneously permits assays in several layers. To demonstrate the effectiveness of this approach, a 3DμPADs was designed to conduct more assays on a small footprint, allowing dual colorimetric and electrochemical detections. More importantly, we further developed a 3D platform for implementing automated and multiplexed ELISA in parallel, since ELISA, a routine and standard laboratory method, has rarely been used in practical analyses outside of the laboratory. In this configuration, complex and multistep diagnostic assays can be carried out with the addition of the sample and buffer in a simple fashion. Using Troponin I as model, the device showed a broad dynamic range of detection with a detection limit of 0.35 ng/mL. Thus, the developed platforms allow for various assays to be cost-effectively carried out on a single 3D device, showing great potential in an academic setting and point of care testing under resource-poor conditions.

Microfluidic paper-based analytical devices (μPADs) for detection of hydrogen peroxide and glucose have been developed. The analytical performance of colorimetric detection using the conventional starch-iodine color reaction has been significantly improved by using gelatin as the surface modifier which retains the enzyme activity in the dry filter paper strip, improves antioxidability, as well as decreases the strong background signal. Under optimal conditions, the color intensities show a good linear relationship with glucose concentration ranging from 0.5 to 5 mM and hydrogen peroxide concentration from 0.5 to 6 mM, with the detection limit of 0.05 mM and 0.1 mM, respectively. In addition, the accuracy of colorimetric sensor has been successfully assessed in detecting glucose from real human serum samples and recovery value ranges from 95.7% to 97%, which are approaching to the glucose oxidase endpoint. The new colorimetric assay exhibits high sensitivity, good selectivity, acceptable stability and reproducibility. The present approach is promising for monitoring glucose for point of care diagnostic applications, especially in regions with resource-limited settings.

The application of microfluidics for largescale rapid analytics holds great promise in the pharmaceutical diagnostics and analytical chemistry. Here we report a paper based microfluidic substrate designed by the impregnation of Silver nanoparticles. This study demonstrates the achievement of a thousand-fold increase in the successful detection level up to 10 ppb (90.8 nM) by employing Surface Enhanced Raman Spectroscopy (SERS) for the detection of Catechol. The presented sensor exhibits the following main features: (i) high specificity of enzyme (Hemocyanin)-based sensing, (ii) effective SERS sensitivity, (iii) easiness and cost-effectiveness of a paper-based platform. We rationalize these findings using the ab initio DFT simulations using Gaussian 09 whose theoretical calculations reflect the observed experimental Raman peaks.

In this study, an internal circulation-anoxic/aerobic (IC-A/O) process followed by ultrafiltration (UF) and reverse osmosis (RO) system was applied for paper wastewater reclamation. The IC-AO system presented a stable and efficient performance, achieving high removal of chemical oxygen demand (COD), total organic carbon (TOC) and total nitrogen (TN) with methane production rate of 132.8 mL/d. Acute toxicity to Daphnia magna (D. magna) was reduced significantly (83.2%) and the spearman's rank correlation analysis indicated that the toxicity of effluents from each reactor were positively correlated with COD and TOC. Hexadecanoic acid, octadecanoic acid and benzophenone were the main toxic contributors for biological effluent. Microbial community revealed that Anaerolinea was significantly related with organic pollutants. The UF-RO system further removed pollutants and toxicity with the final effluent COD, TOC, ammonium nitrogen (NH4+-N) and TN of 32.6, 18.8, 0.3 and 9.2 mg/L, respectively, which proved that it was feasible for paper wastewater reuse. This study presented an efficient, practical and environmentally competitive system, and paved a foundation for the treatment and reuse of paper wastewater.

The facile detection of phosphopeptides is important for clinical screening and phosphoproteomic research. This work develops an instrument-free, cost-effective, convenient paper-based method for quantitative analysis of phosphorylated peptides. With a novel portable device, Phos-PAD, this method can achieve selective enrichment and colorimetric detection of phosphopeptides within 15 min TiO2 nanoparticle-based chemisorption and tetrabromophenol blue-based colorimetric assay were integrated into the single paper-based analytical device. The color change can indicate the presence of phosphopeptides and the mean pixel intensity of the red channel can be used for phosphopeptide quantification. With capability of quantifying phosphopeptides in serum samples, this Phos-PAD assisted phosphopeptide assay may attract significant attention to clinical analysis of endogenous serum phosphopeptides.

The development of greatly stable and cost-effective electrocatalysts for urea electro-oxidation reactions (UERs) is urgent and challenging for promoting urea removal in the wastewater and advanced energy conversion devices. We demonstrated that nickel-iron borate (NiFe-B) electrocatalysts supported on carbon paper (CP) for UERs through a one-pot solvothermal method. NiFe-B electrocatalysts were obtained with numerous Ni/Fe molar ratios in the precursors, and the physicochemical features of the NiFe-B were examined by X-ray diffraction, scanning and transmission electron microscope, and X-ray photoelectron spectroscopy. The optimized NiFe-B/CP exhibited a low onset potential (Eonset = 0.287 V vs. SCE) with a Tafel slope of 27.9 mV/dec on CP, demonstrating much greater performance UERs. Furthermore, the NiFe-B/CP catalysts have shown a superior activity for the UERs in alkaline solution and exhibit more than two-fold enhancement in activity than Ni-B. Facile, cost-effective fabrication and highly efficient urea oxidation create the NiFe-B electrodes as attractive materials for UERs.

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.