Search

Background Measuring concentrations of metabolites of estradiol and progesterone in urine, instead of measuring serum concentrations, is common in research and also is used in patient care. The primary aim of this study was to demonstrate that analysis of urine samples dried on filter paper by gas chromatography with tandem mass spectrometry (GC–MS/MS) provides results similar to serum analyzed by radioimmunoassay (RIA). Secondary aims were to show that collection of four samples during the day (4-spot method) can be substituted for a 24-h collection, and that analysis of urine from dried samples is equivalent to liquid urine samples. Methods This prospective observational study compared results of urine and serum analyses. Urine samples from women throughout the menstrual cycle and single samples from postmenopausal women were evaluated. Urine was collected onto filter paper and dried. Dried urine was extracted, hydrolyzed, and derivatized prior to analysis by GC–MS/MS. Hormone concentrations were normalized to creatinine. Single samples were used to compare results of 24-h urine collection to the 4-spot method from a separate population of women and men. A subset of these samples were used to compare results from dried urine to liquid urine. Results The primary study showed good reliability in the comparisons between the dried urine and serum assays. During the menstrual cycles of a subset of four women, urine metabolite concentrations followed the same pattern as serum concentrations. Comparison of 4-spot to 24-h urine collections and of dried to liquid urine measurements had intraclass correlation coefficients (ICC) greater than 0.95, indicating excellent agreement. Conclusions For estradiol and progesterone, the dried urine assay is a good surrogate for serum testing. The 4-spot method can be used instead of 24-h urine collections and dried urine results are comparable to liquid urine. The dried urine assay is useful for some clinical assessments of hormone disorders and may be useful in large epidemiologic studies due to ease of sample handling. Electronic supplementary material The online version of this article (10.1186/s13065-019-0539-1) contains supplementary material, which is available to authorized users.

Bulk graphitic carbon materials with expanded interlayer spacing and abundant defects may serve as efficient anodes with high areal capacities for sodium-ion batteries (SIBs). However, obtaining long-range order in bulk graphitic carbon materials with expanded interlayer spacing is extremely difficult. Herein, an explosive decomposition method is demonstrated to realize thermally reduced graphene oxide (rGO) paper with tuned interlayer spacing. The in-situ temperature-dependent X-ray diffraction (td-XRD) was utilized to establish the correlation between heating rate and interlayer spacing. Based on td-XRD results, free-standing graphene paper (FSG) was synthesized at 450°C under a high heating rate of 70°C/min. The FSG exhibits a highly porous structure made of graphene flakes with abundant surface epoxy groups with an overall interlayer spacing of 0.38–0.39 nm. The rGO flakes in FSG are separated by large voids that provide fast mass transport pathways and allow expansion/contraction of crystallites upon reversible Na intercalation. The FSG was utilized directly as anodes without any binder and conductive agent and delivered an excellent reversible capacity of 290 mAh/g at a current density of 50 mA/g. Moreover, the FSG exhibited excellent foldability and rollability to create high areal density anodes, delivering an areal capacity of 0.62 mAh/cm2 at a current density of 100 μA/cm2. These results open the door to fabricate graphene material-based carbon anodes with tunable interlayer spacing for high-performance SIBs.

Paper sludge is a solid waste by-product abundantly produced in the paper industry and contains fine minerals and lignocellulosic biomass. In this contribution, the ex-situ catalytic fast pyrolysis of paper sludge with a high mineral content of ca. 71 wt% is reported for the first time and demonstrated in a pilot-scale unit (feeding rate of 11.3 kg h−1) using a granular Na2CO3/γ-Al2O3 catalyst (loading of 650 g) to produce a high-grade bio-oil at a fast pyrolysis temperature of 475 ± 5 °C (pre-screened using a pyroprobe) and a catalytic upgrading temperature of 500 °C. Besides, > 99 wt% minerals in the paper sludge could be recovered, including paper fillers such as CaCO3 (major) and talc. The bio-oil obtained at a carbon yield of 21 C.% has a low oxygen content of 3.2 wt%, a low total acidity number of 5.2 mg KOH g−1, low H2O content of 0.7 wt%, and a high higher heating value of 40.9 MJ kg−1. It consists of value-added bio-based chemicals such as paraffins, olefins, and low molecular weight aromatics. The results demonstrate that the use of paper sludge to recover minerals and to obtain fuels and chemicals using ex-situ catalytic pyrolysis is technically feasible at a pilot plant scale, which will be of importance for the development of future bio-based economy.

To study the influence of different concentrations of zinc oxide (ZnO)/silicon dioxide (SiO2) composite coating on hydrophobic property and mechanical stability of paper mulch film, three kinds of ZnO/SiO2 composite coating paper mulch films (2%, 4%, 6%) with different coating substance contents were prepared by brush coating method. Through particle size analysis, contact angle, rolling angle and mechanical stability test, combined with scanning electron microscope, three-dimensional morphology and roughness measuring instrument, the optimal concentration of ZnO/SiO2 composite coated paper mulch film was screened out. Through acid-base salt corrosion test, silver mirror reaction and surface self-cleaning, the optimal concentration of composite coated paper mulch film was compared with the original paper mulch film to prove its excellent chemical stability and hydrophobicity. The results show that the paper mulch film with 4% coating material has excellent hydrophobicity and mechanical stability, can effectively reduce the surface roughness of paper mulch film, and has remarkable effects in resisting acid, alkali and salt and self-cleaning.

The fabrication of low-cost, flexible, and recyclable electronic devices has been the focus of many research groups, particularly for integration in wearable technology and the Internet of Things (IoT). In this work, porous zinc oxide (ZnO) nanostructures are incorporated as a UV sensing material into the composition of a sustainable water-based screen-printable ink composed of car-boxymethyl cellulose (CMC). The formulated ink is used to fabricate flexible and foldable UV sensors on ubiquitous office paper. The screen-printed CMC/ZnO UV sensors operate under low voltage (≤2 V) and reveal a stable response over several on/off cycles of UV light exposure. The devices reach a response current of 1.34 ± 0.15 mA and a rise and fall time of 8.2 ± 1.0 and 22.0 ± 2.3 s, respectively. The responsivity of the sensor is 432 ± 48 mA W−1, which is the highest value reported in the literature for ZnO-based UV sensors on paper substrates. The UV-responsive devices display impressive mechanical endurance under folding, showing a decrease in responsivity of only 21% after being folded 1000 times. Their low-voltage operation and extreme folding stability indicate a bright future for low-cost and sustainable flexible electronics, showing potential for low-power wearable applications and smart packaging. publishersversion published

Currently, there is an increasing interest in the use of biopolymers in industrial applications to replace petroleum-based additives, since they are abundantly available, renewable and sustainable. Cottonseed protein is a biopolymer that, when used as a modifier, has shown improved performance for wood adhesives and paper products. Thus, it would be useful to explore the feasibility of using cellulose nanomaterials to further improve the performance of cottonseed protein as a paper strength agent. This research characterized the performance of cottonseed protein isolate with/without cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) to increase the dry strength of filter paper. An application of 10% protein solution with CNCs (10:1) or CNFs (50:1) improved the elongation at break, tensile strength and modulus of treated paper products compared to the improved performance of cottonseed protein alone. Further analysis using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that the cottonseed protein/nanocellulose composites interacted with the filter paper fibers, imparting an increased dry strength.

Point-of-care monitoring of hydrogen peroxide is important due to its wide usage in biomedicine, the household and industry. Herein, a paper sensor is developed for sensitive, visual and selective detection of H2O2 using a mesoporous metal oxide hollow sphere as a nanozyme. The mesoporous CuO hollow sphere is synthesized by direct decomposition of copper–polyphenol colloidal spheres. The obtained mesoporous CuO hollow sphere shows a large specific surface area (58.77 m2/g), pore volume (0.56 cm3/g), accessible mesopores (5.8 nm), a hollow structure and a uniform diameter (~100 nm). Furthermore, they are proven to show excellent peroxidase-like activities with Km and Vmax values of 120 mM and 1.396 × 10−5 M·s−1, respectively. Such mesoporous CuO hollow spheres are then loaded on the low-cost and disposable filter paper test strip. The obtained paper sensor can be effectively used for detection of H2O2 in the range of 2.4–150 μM. This work provides a new kind of paper sensor fabricated from a mesoporous metal oxide hollow sphere nanozyme. These sensors could be potentially used in bioanalysis, food security and environmental protection.

This study is the first, to the best of our knowledge, where waste napkin paper was successfully valorized to low-density (27.2 mg cm−3) cellulose aerogels for oil sorption material. Two simple methods with different gel coagulators, ethanol and sulfuric acid, were used for preparation of the aerogel. Conditions for the alkaline treatment of the raw material and the pre-freezing temperature in the lyophilization process were optimized. It was found that the water and oil sorption capacities of the aerogels were not significantly affected by alkaline treatment, while they could be adjusted by changing the pre-freezing temperature. Although the produced aerogels were initially amphiphilic, hydrophobic surfaces were obtained by vapor deposition of methyltrimethoxysilane (MTMS) and these materials possessed high sorption capacities, up to 32.24 cm3 g−1 (28.56 g g−1) for pump oil and 26.77 cm3 g−1 (39.59 g g−1) for chloroform. This was comparable to aerogels prepared from fresh cellulosic materials via the sol-gel method, as their sorption capacities varied in the range of 14–45 g g−1.

Cannabinoids present a unique set of analytical challenges. An increasing number of states have voted to decriminalize recreational marijuana use, creating a need for new kinds of rapid testing. At the same time, synthetic compounds with activity similar to THC, termed synthetic cannabinoids, have become more prevalent and pose significant health risks. A rapid method capable of detecting both natural and synthetic cannabinoids would be useful in cases of driving under the influence of drugs, where it might not be obvious whether the suspect consumed marijuana, a synthetic cannabinoid, or both. Paper spray mass spectrometry is an ambient ionization technique which allows for the direct ionization of analyte from a biofluid spot on a piece of paper. Natural cannabinoids like THC, however, are labile and rapidly disappear from dried sample spots, making it difficult to detect them at clinically relevant levels. Presented here is a method to concentrate and preserve THC and synthetic cannabinoids in urine and oral fluid on paper for analysis by paper spray mass spectrometry. Sesame seed oil was investigated both as a means of preserving THC and as part of a technique, termed paper strip extraction, wherein urine or oral fluid is flowed through an oil spot on a strip of paper to preconcentrate cannabinoids. This technique preserved THC in dried biofluid samples for at least 27 days at room temperature; paper spray MS/MS analysis of these preserved dried spots was capable of detecting THC and synthetic cannabinoids at low ng/mL concentrations, making it suitable as a rapid screening technique. The technique was adapted to be used with a commercially available autosampler.

Cellulose is the main component of transformer insulating paper. In this paper, the pyrolysis mechanism of cellulose is studied by means of computational chemistry. This study is aimed at exploring the generation process of the methanol from cellulosic insulating paper at the atomic level. A simulation scheme of cellulose pyrolysis with detailed reaction pathways for methanol production has been obtained that is not readily accessible by experiments. The molecular dynamics method based on reactive force field (ReaxFF) is adopted to simulate the pyrolysis of cellobiose. A model composed of 40 cellobioses simulated at 500–3000 K was established, and the force biased monte-carlo is mixed into ReaxFF to make it closer to the actual situation and ensure the reliability. The result reveals that the –CH2– group from the C5 (or $${\text{C}}_{ 5}^{{\prime }}$$) group in cellobioses grabbed the nearby H atom to form methanol. In the pyrolysis process of cellobioses, methanol is stable at the early stage but unstable even disappeared in the later stage. The pre-exponential factor A and activation energy Ea of the ReaxFF-MD simulation are consistent with previous experimental results. Thus, this study provides an effective theory of the methanol as an indicator to evaluate the aging condition of cellulosic insulating paper in the early stage at the atomic level.

Monitoring of human serum albumin (HSA) in a point-of-care fashion is urgently needed in particular for elderly or chronically ill patients. Herein, a dual-state emissive chalcone probe having the feature of aggregation-induced emission was designed and synthesized. The concentration of HSA can be evaluated by the ratios of emission from probes in aggregated and monomeric state, which gives a visually discernible red-to-green color change. A simple, portable paper-based analytical device have been fabricated by integration of the recognition probe in the detection pad and employed for HSA test using the whole blood samples. This paper-based assay shows the analytical capability comparable to the standard testing methods but is in a point-of-care fashion, providing a promising tool for at-home HSA detection and HSA-related disease diagnosis.

In the present article we report a new hybrid microfluidic device (hyFlow) comprising a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. This hybrid device evolved due to the difficulty of incorporating micron-scale MBs into paper-only fluidic devices. Specifically, paper fluidic devices can entrap MB-containing conjugates within their cellulose or nitrocellulose fiber matrix. The hyFlow system was designed to minimize such issues and transport MB conjugates more efficiently to the electrochemical detection zone of the device. The hyFlow system retains the benefit of fluid transport by pressure-driven flow, however, no pump is required for its operation. The hyFlow device is capable of detecting either pre-formed MB-AgNP conjugates or conjugates formed in-situ formation. The detection limit of AgNPs using this device is 12 pM, which represents just 22 AgNPs per MB.

Sensors based on fluorogenic RNA aptamers have emerged in recent years. These sensors have been used for in vitro and intracellular detection of a broad range of biological and medical targets. However, the potential application of fluorogenic RNA-based sensors for point-of-care testing is still little studied. Here, we report a paper substrate-based portable fluorogenic RNA sensor system. Target detection can be simply performed by rehydration of RNA sensor-embedded filter papers. This affordable sensor system can be used for the selective, sensitive, and rapid detection of different target analytes, such as antibiotics and cellular signaling molecules. We believe that these paper-based fluorogenic RNA sensors show great potential for point-of-care testing of a wide range of targets from small molecules, nucleic acids, proteins, to various pathogens.

The single-use of large volumes of paper has become a serious issue which is depleting our resources and damaging the environment. It is of great significance and challenging to adopt simple, reasonable and practical methods to prepare functional recyclable paper. In this article, inspired by pleochromatic creatures and plant leaves' special wettability, a series of photochromic amphiphobic recycled paper (PARi) products was successfully prepared by adding gourd-like modified tungsten trioxide (MTT) to waste paper pulp. The results show that PAR2–7 has excellent lyophobic performance and amazing photochromic properties. It is worth noting that PAR7 has an impressive amphiphobic behavior, and its surface water contact angle (WCA) and oil contact angle (OCA) are 146 ± 1° and 137 ± 1°, respectively. It can withstand continuous ultraviolet light irradiation for 60 h, indicating excellent resistance to ultraviolet radiation. Most importantly, the reversible photochromic properties of PAR7 make it possible to write repeatedly on the surface by using ultraviolet light. In short, the performance of the prepared PAR is stable and superior, which can not only alleviate paper waste, but also means it has great potential in the fields of decoration, packaging, and banknote anti-counterfeiting technology.

An electrical tree discharge model of multilayer insulation paper was prepared, and a voltage of 20 kV was used for electrical tree cultivation and initiation tests. Based on the microscopic image information and partial discharge (PD) information during the aging of the electrical tree, the development of electrical tree discharges between layers of paper comprising epoxy resin-impregnated paper insulation was studied. The results show that, by analysing PD information such as the discharge volume phase spectrum and the discharge repetition rate phase spectrum, the development of the electrical tree branch progresses in four stages: initial, growth, stagnation, and bursting. During the growth and stagnation stages, the main discharge paths of the electrical tree are mainly formed, and there are many filamentous fibres on the path edge. During the burst stage, more branches will be formed on the electrical tree, which will cause the greatest damage to the insulation. With the extension of the electrical tree path, the discharge magnitude and discharge times also increase. There are specific discharge patterns in different growth stages of the electrical tree, and the number of discharge events in each positive half-cycle is significantly greater than that in a negative half-cycle. Combining the microscopic image information and PD information during the aging of such an electrical tree, a theoretical basis for evaluating insulation state by PD monitoring is realised. The long-chain molecules of cellulose and epoxy resin break bonds and oxidise, which decompose into a large number of free radicals, monosaccharides, and other low-molecular-weight products.

This work reports the development of a rapid, simple and inexpensive colorimetric paper-based assay for the detection of the severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) humanized antibody. The paper device was prepared with lamination for easy sample handling and coated with the recombinant SARS-CoV-2 nucleocapsid antigen. This assay employed a colorimetric reaction, which is followed by horseradish peroxidase (HRP) conjugated detecting antibody in the presence of the 3,3',5,5'-tetramethylbenzidine (TMB) substrate. The colorimetric readout was evaluated and quantified for specificity and sensitivity. The characterization of this assay includes determining the linear regression curve, the limit of detection (LOD), the repeatability, and testing complex biological samples. We found that the LOD of the assay was 9.00 ng μL-1 (0.112 IU mL-1). The relative standard deviation was approximately 10% for a sample number of n = 3. We believe that our proof-of-concept assay has the potential to be developed for clinical screening of the SARS-CoV-2 humanized antibody as a tool to confirm infected active cases or to confirm SARS-CoV-2 immune cases during the process of vaccine development.

A new type of hydrogel-coated paper sensor was developed for the semiquantitative and naked-eye detection of Cu2+ ions with high selectivity and good regenerability. The paper sensor showed a continuous color change from colorless to blue, resulting in semiquantitative naked-eye detection. Furthermore, similar to the classical pH test paper, a standard colorimetric card was used in the visual detection of Cu2+ ions by identifying the RGB value of the hydrogel-coated paper sensor. The application of the standard colorimetric card has greatly shortened the detection time and reduced the cost of detection, providing a new strategy for the naked-eye and semiquantitative detection of heavy-metal ions in water samples.

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.

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.

Paper spray ionization has been used as a fast sampling/ionization method for the direct mass spectrometric analysis of biological samples at ambient conditions. Here, we demonstrated that by utilizing paper spray ionization-mass spectrometry (PSI-MS) coupled with field asymmetric waveform ion mobility spectrometry (FAIMS), predictive metabolic and lipidomic profiles of routine breast core needle biopsies could be obtained effectively. By the combination of machine learning algorithms and pathological examination reports, we developed a classification model, which has an overall accuracy of 87.5% for an instantaneous differentiation between cancerous and noncancerous breast tissues utilizing metabolic and lipidomic profiles. Our results suggested that paper spray ionization-ion mobility spectrometry-mass spectrometry (PSI-IMS-MS) is a powerful approach for rapid breast cancer diagnosis based on altered metabolic and lipidomic profiles.

In this study, we developed a simple, inexpensive and easily fabricable paper-based SERS substrate with high sensitivity and reproducibility. The filter paper has natural pleats and small pores that allow the metal nanoparticles to be deposited and arranged on the paper to form large area SERS ‘active sites’. Silver nanoparticles can be embedded and grown on cellulose nanocrystals framework through the in situ reduction to form cellulose nanocrystal–silver (CNC–Ag) composites, which are coated on the filter paper to form composite paper-based substrates. The CNC–Ag composites further filled the pores on the surface of the filter paper and improved the adhesive rate of metal nanoparticles, thus the reproducibility of the SERS sensor has been improved. At the same time, because it has the agglomerating effect on samples, the hydrophobic dodecyl mercaptan covered on paper-based substrates can improve detection limit of analyte. Furthermore, we demonstrate that paper-based SERS substrates can efficiently detect two substances, including phenylethanolamine A and metronidazole. The limits of detection for phenylethanolamine A and metronidazole were found to as low as 5 × 10−9 M and 2 × 10−7 M, respectively. The paper-based SERS substrates offer great potential for label-free and on-site detection of trace substances.

Effective separation of oil and water has always been a long-term challenge. Here we introduce a facile and fluorine-free method to fabricate superhydrophobic and superoleophilic filter paper without the decoration of solid particles for robust oil/water separation. After chemically bonding octadecanoyl and α-bromoisobutyryl groups on the surface of filter paper through simultaneous esterification with stearoyl chloride and α-bromoisobutyryl bromide (BiBB) to obtain C18-FP-g-Br, superhydrophobic poly(styrene-co-acrylonitrile) (SAN) grafted filter paper (C18-FP-g-SAN) was fabricated via surface-initiated atom transfer radical polymerization. The obtained C18-FP-g-SAN showed a water contact angle of 153° and achieved a separation efficiency exceeding 98.5% after ten different typical oil/water separation processes due to the synergistically combined contributions of bonded octadecanoyl chain and grafted SAN. C18-FP-g-SAN remained high separation efficiency after 10 cycles of use and treatment with strong acidic or basic solution. The excellent reusability and chemical stability of C18-FP-g-SAN promise its practical applications of continuous oil/water separation and oil spillage cleanup.

A procedure for the rapid simultaneous determination of anthraquinone and bisphenol A in paper and cardboard is proposed based on a combination of extraction with subcritical methanol and subsequent analysis of the extracts by HPLC‒tandem mass spectrometry. The achieved limits of detection are 25 and 250 µg/kg for anthraquinone and bisphenol A, respectively, and fully meet present-day safety requirements for pulp and paper products. The total duration of the analysis, including sample preparation, is not more than 45 min. The sensitivity of anthraquinone determination is 1‒2 orders of magnitude higher than that of the known procedures, including those with the preconcentration of analytes. The results obtained were successfully used to study paper and cardboard samples, in most of which unacceptably high levels of the anthraquinone concentration were found.

Paper-based flexible surface-enhanced Raman scattering (SERS) chips have been demonstrated to have great potential for future practical applications in point-of-care testing (POCT) due to the potentials of massive fabrication, low cost, efficient sample collection and short signal acquisition time. In this work, common filter paper and Ag@SiO2core-shell nanoparticles (NP) have been utilized to fabricate SERS chips based on shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS). The SERS performance of the chips for POCT applications was systematically investigated. We used crystal violet as the model molecule to study the influence of the size of the Ag core and the thickness of the SiO2coating layer on the SERS activity and then the morphology optimized Ag@SiO2core-shell NPs was employed to detect thiram. By utilizing the smartphone as a miniaturized Raman spectral analyzer, high SERS sensitivity of thiram with a detection limit of 10−9M was obtained. The study on the stability of the SERS chips shows that a SiO2shell of 3 nm can effectively protect the as-prepared SERS chips against oxidation in ambient atmosphere without seriously weakening the SERS sensitivity. Our results indicated that the SERS chips by SHINERS had great potential of practical application, such as pesticide residues detection in POCT.

Chemiluminescence (CL) immunoassays for simultaneous detection of early acute myocardial infarction (AMI) biomarkers, including copeptin, heart-type fatty acid binding protein (h-FABP), and cardiac troponin I (cTnI), were developed by using Co2+/N-(aminobutyl)-N-(ethylisoluminol) (ABEI) functionalized magnetic carbon composite (Co2+-ABEI-Fe3O4@void@C) as an interface and a three-dimensional microfluidic paper-based device (3D μPAD) as a detection system. For CL immunoassays, Co2+-ABEI-Fe3O4@void@C was assembled with chitosan (CS) and gold nanoparticle-conjugated antibody (Au-Ab) sequentially to form the sensing platform (Co2+-ABEI-Fe3O4@void@C-CS/Au-Ab). In the presence of antigen (Ag), Ag was captured by the sensing interface to form an immunocomplex, leading to an increase in CL intensity due to the catalysis of -COO- existing in Ag. A 3D μPAD with three detection zones for simultaneous detection of copeptin, h-FABP, and cTnI was designed and fabricated to obtain time-resolved CL signals. Three kinds of immunocomplexes formed with copeptin, h-FABP, and cTnI were added to three detection zones of 3D μPAD, respectively. After injecting H2O2, three time-resolved CL signals were generated in one CL detection run by virtue of time-delayed transport of H2O2 to different detection zones. The three time-resolved CL signals were used for the simultaneous determination of copeptin, h-FABP, and cTnI. The detection limit of copeptin, h-FABP, and cTnI was 0.40 pg/mL, 0.32 pg/mL, and 0.50 pg/mL, respectively, which is at least 1 order of magnitude lower than most of the reported immunoassays. The immunoassays could be directly used for the detection of copeptin, h-FABP, and cTnI in human serum samples. The proposed immunoassays are simple, fast, sensitive, and selective, and are of great application potential in early diagnosis and treatment of AMI.

Paper-based devices are always more gaining a relevant position in the field of sensors. The continuous demand for affordable, simple, sustainable, and portable devices, is making paper as the ideal basis towards the realization of analytical tools for the easy self-testing. In this work, we demonstrate, for the first time, the development of a disposable paper-based printed electroanalytical strip for reliable, rapid, and high-throughput detection of glutathione in blood. The detection is based on the thiol-disulfide exchange reaction, which produces a detectable compound easily oxidizable at a Prussian Blue/carbon black nanocomposite involving a favorable low-interference overpotential. This nanocomposite is mixed within a carbon-based conductive ink and successively screen-printed onto a wax-patterned filter paper. The employment of paper provides a reagent-free device, as a consequence of the reagents pre-loading within the testing area. After the experimental conditions have been optimized, glutathione has been detected up to 10 mM, with a detection limit of 60 μM, and a sensitivity of (0.102 ± 0.005) μA/mM. This sensor showed satisfactory repeatability (relative standard deviation equal to 10%, for detection of glutathione 1 mM), especially by considering the hand-made manufacturing process. The “real-world” applicability of this strip has been evaluated by quantifying blood glutathione at physiological levels and by recovery studies achieving satisfactory values.

The development of renewable energy sources minimizes the burning of fossil fuels for clean and green environment. Electrochemical energy storage/conversion device pays a way towards sustainable development that concludes an emerging field in the trends of the research community. Prominently, the functional materials with suitable structure and property determine the performance and durability of the devices. In recent times, graphene with its tremendous properties play a major role in electrochemical energy device applications. Meanwhile, the graphene-based electrodes were fabricated by various coating techniques on existing electrodes that utilized for energy device fabrication. Apart from these, it is also fabricated in a paper like a form (self-supported or free-standing) with its remarkable high conductivity, flexibility, robustness and electrochemical behavior which have been nominated for fabrication of flexible energy devices. Paper-like electrodes become an emerging field to fabricate a light-weight and flexible electronic devices for future prospects. Thus, we have summarized a synthetic strategy of graphene paper and its properties that potentially focused on flexible device fabrication in both the energy storage and conversion system. Hence, this review boosts up the forthcoming researchers to enhance the device performance with interrelating free-standing graphene and other host material.

Fluoro-functionalized paper was prepared and applied in solid phase extraction (SPE) for the analysis of trace-level perfluorinated compounds (PFCs). The proposed fluoro-functionalized paper-based solid-phase extraction (Fp-SPE) exhibits significant advantages for sample preparation, such as the biodegradability of paper-based adsorbent, simple manipulation and low cost. Owing to the fluorous affinity, the Fp-SPE technique with high sensitivity and high selectivity is more suitable for the selective enrichment of fluorine-containing molecules from the background of non-fluorinated organic compounds in a real water sample. Combined with high-performance liquid chromatography coupled with electrospray ionization-tandem mass spectrometry analysis (HPLC-MS/MS), the linear range of the PFCs, including perfluorobutyric acid (PFBA), perfluorooctanic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorodecanoic acid (PFDA), was 0.20–5.0 ng/L with the limits of detection (LOD) ranging from 0.04–0.05 ng/L and the limits of quantification (LOQ) ranging from 0.15-0.20 ng/L. The method was then applied to the analysis of tap water, river water and waste water samples. The results of the actual sample analysis are consistent with that by reverse phase SPE (RP-SPE).

In recent years, there has been high interest in paper-based microfluidic sensors or microfluidic paper-based analytical devices (μPADs) towards low-cost, portable, and easy-to-use sensing for chemical and biological targets. μPAD allows spontaneous liquid flow without any external or internal pumping, as well as an innate filtration capability. Although both optical (colorimetric and fluorescent) and electrochemical detection have been demonstrated on μPADs, several limitations still remain, such as the need for additional equipment, vulnerability to ambient lighting perturbation, and inferior sensitivity. Herein, alternative detection methods on μPADs are reviewed to resolve these issues, including relatively well studied distance-based measurements and the newer capillary flow dynamics-based method. Detection principles, assay performance, strengths, and weaknesses are explained for these methods, along with their potential future applications towards point-of-care medical diagnostics and other field-based applications.

A facile and feasible method for decoration of iron oxide (Fe3O4) submicron-sized particles on carbon paper at room temperature in a short time of 10 min is demonstrated in this work. The Fe3O4-particles decorated carbon papers were used as the negative electrode for an Fe-air rechargeable battery in both an alkaline aqueous solution system and an all-solid-state system. As for the all-solid-state Fe-air rechargeable battery, KOH-ZrO2 electrolyte powder developed by our group was used in the battery fabrication. In the alkaline aqueous solution based Fe-air rechargeable battery, a high initial discharge capacity of 460 mAh g−1(Fe) was achieved. Meanwhile, in the novel all-solid-state Fe-air rechargeable battery system, an initial discharge capacity of 70 mAh g−1(Fe) was obtained demonstrating the feasibility of this system that could be further developed towards a practical Fe-air rechargeable battery for portable and lightweight device application.

Paper industry being a mature mega-scale industry is focusing on process oriented technical modifications to reduce dependency on wood fibers and resource utilization. In this research study, conventional chlorine dioxide (D0) bleaching method was modified to hot chlorine dioxide (DHT) with an aim of reducing the effluent load with special concern to chlorolignin compounds. These compounds were measured by gas chromatograph equipped with ECD detector. The chlorophenols, chlorocatechols, chloroguaiacols, chlorovanillins, chlorosyringols and bromophenols were reduced by 9%, 50%, 34%, 47%, 17% and 31%, respectively under DHT based sequence at same dose of chemicals. The general environmental parameters i.e. COD, BOD, TS, colour, lignin and AOX also got reduced in DHT based sequence. The modification of D0 to DHT was found to be effective as effluent quality was enhanced without compromising the optical and strength properties of cellulosic paper even at low dose of chlorine dioxide.

Great attention has been drawn to flexible and portable electronic devices, so it is important to develop flexible energy-storage devices. In this study, the porous Ni-Co-N nanosheets on flexible graphene paper (GP) are prepared by surface nitridation of NiCo2O4 nanosheets. Compared with NiCo2O4/GP, Ni3N/GP and CoN/GP, Ni-Co-N/GP shows superior performance in terms of specific capacitance of 960 F/g (48.1 mF/cm2) at 4 A/g, rate performance (86% capacitance retention) and cycle life (the capacitance retention reaches 95% over 5000 cycles). The paper-based all-solid-state asymmetric supercapacitors (SCs) are manufactured based on Ni-Co-N/GP and chemical oxidized GP (graphene oxide paper, GOP), which exhibits excellent bendability, flexibility, editability. The flexible energy device shows an outstanding specific energy of 4.78 mWh/cm3 and excellent cycle life (89% capacitance retention after 8000 cycles).

We introduce a facile and low-cost method for fabricating gold nanostructures on cellulose filter paper (CFP) to prepare a paper-based surface-enhanced Raman scattering (SERS) sensor for label-free molecular detection. Polymerized dopamine (PD) was used as an adhesive layer on the CFP and simultaneously functioned as a reducing agent for gold nanoparticle (AuNP) nucleation. The size of the AuNPs was dependent on the pH of the gold precursor solution, and nanoparticles with an average size of 102 nm were formed on the PD-coated CFP at a pH 3, exhibiting high SERS activity. Finite-difference time-domain (FDTD) simulations of the electromagnetic field enhancement of AuNPs with different sizes and interparticle distances were performed to identify the origin of the SERS effect. The developed paper-based SERS substrate showed uniform and excellent molecular sensitivity with a limit of detection (LOD) of 10−7 M for methylene blue, as measured by a portable Raman spectrometer. Furthermore, as a field application test, surfaces of apples were pretreated with diquat (DQ) and paraquat (PQ) pesticides, which were then detected down to a concentration of 1 ppm after simple attachment of the sensor on the apple peels and performing a SERS measurement. The developed paper-based SERS sensor is expected to be applicable as a label-free sensor for a variety of chemical and biological molecules.

The construction of flexible electrochemical devices for energy storage and generation is of utmost importance in modern society. In this article, we report on the synthesis of flexible MoS2-based composite paper by high-energy shear force milling and simple vacuum filtration. This composite material combines high flexibility, mechanical strength and good chemical stability. Chronopotentiometric charge–discharge measurements were used to determine the capacitance of our paper material. The highest capacitance achieved was 33 mF·cm−2 at a current density of 1 mA·cm−2, demonstrating potential application in supercapacitors. We further used the material as a cathode for the hydrogen evolution reaction (HER) with an onset potential of approximately −0.2 V vs RHE. The onset potential was even lower (approximately −0.1 V vs RHE) after treatment with n-butyllithium, suggesting the introduction of new active sites. Finally, a potential use in lithium ion batteries (LIB) was examined. Our material can be used directly without any binder, additive carbon or copper current collector and delivers specific capacity of 740 mA·h·g−1 at a current density of 0.1 A·g−1. After 40 cycles at this current density the material still reached a capacity retention of 91%. Our findings show that this composite material could find application in electrochemical energy storage and generation devices where high flexibility and mechanical strength are desired.Keywords: flexible composites; hydrogen evolution reaction (HER); lithium ion batteries (LIBs); molybdenum disulfide; nanoarchitectonics; supercapacitors

This study aims to decrease the dielectric constant of cellulose insulating paper by octa(aminophenyl)silsesquioxane (OAPS) grafting. OAPS was grafted onto the primary hydroxyl group of cellulose molecules via amino groups and epichlorohydrin. The dielectric constant and dielectric loss of insulating paper before and after modification were investigated. Relative to the unmodified paper, the dielectric constant of 15 wt% OAPS-grafted paper decreased from 5.27 to 4.28, and the dielectric loss decreased by 37.5% at 50 Hz. The movement and orientation polarization of the cellulose chains could be restricted due to the porous macromolecular structure and nano quantum interface effect produced by OAPS, thereby resulting in the reduction of cellulose polarizability. Moreover, the OAPS grafting modification does not degrade the other properties of cellulose insulation, i.e., its thermal stability, mechanical performance, fire-resistant properties, and electrical strength. OAPS grafting has promising potential application for preparing low dielectric constant insulating paper.

Selective detection of different explosive materials is essential to the current world scenario from the perspective of health, safety, and environment. Here, we have developed and characterized a couple of bio-based conjugated systems, viz. cholesterol-tryptophan and cholesterol-cysteine for the detection of nitroaromatic explosive chemicals. The presence of tryptophan moiety introduces fluorescence property to the non-fluorescence cholesterol backbone, and hence it was used as a tag molecule to prepare photoluminescent filter papers which serve as indicators for picric acid and dinitrosalicylic acid. These paper strips undergo instant quenching in the presence of the experimental analytes under the UV irradiation, which could be visualized through the naked eye. The amount of quenching is found to be proportional to the concentration of the analytes. The limit of detection for picric acid and dinitrosalicylic acid was estimated to be about 33 nM and 48.7 nM respectively, and the mechanism of this quenching is mainly due to fluorescence resonance energy transfer between the fluorophore and the quencher. Also, the vapor of picric acid completely diminishes the photoluminescence of the filter papers. Such an easy, selective and instant detection of nitroaromatic chemicals is in high demand due to increasing health and security concern worldwide.

One of the most important problems in dark fermentative hydrogen production is the need for the regulation of the ambient pH due to the formation of volatile fatty acids. For this purpose, alkaline chemicals are usually used; however, alkaline addition to the media increases salt formation, which negatively affects microbial activity. In this study, pH adjustment was performed by providing direct current as an alternative to alkali addition. Experiments were carried out batchwise and electricity was only applied to neutralize the acidic pH value. The waste paper hydrolysate was used as a substrate and the effects of applied voltage (0.25-3 V), substrate concentration (4.8-41.2 g/L at 1 V) and electrode distance (0.3-1.3 cm at 1 V) on hydrogen production performance was investigated. Voltages less than 1 V required too much time to keep the pH convenient and voltages more than 1.5 V adversely affected hydrogen production performance. Providing direct current to the fermentation media significantly reduced the adaptation phase. Conditions for optimal pH adjustment and hydrogen production were obtained at 1 V, 20 g glucose/L and 0.5 cm electrode distance. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Flexible and wearable pressure sensors are of paramount importance for the development of personalized medicine and electronic skin. However, the preparation of easily disposable pressure sensors is still facing pressing challenges. Herein, we have developed an all paper-based piezoresistive (APBP) pressure sensor through a facile, cost-effective, and environmentally friendly method. This pressure sensor was based on a tissue paper coated with silver nanowires (AgNWs) as a sensing material, a nanocellulose paper (NCP) as a bottom substrate for printing electrodes, and NCP as a top encapsulating layer. The APBP pressure sensor showed a high sensitivity of 1.5 kPa-1 in the range of 0.03-30.2 kPa and retained excellent performance in the bending state. Furthermore, the APBP sensor has been mounted on the human skin to monitor physiological signals (such as arterial heart pulse and pronunciation from throat) and successfully applied as a soft electronic skin to respond to the external pressure. Due to the use of the common tissue paper, NCP, AgNWs, and conductive nanosilver ink only, the pressure sensor has advantages of low cost, facile craft, and fast preparation and can be disposed off easily by incineration. We believe that the developed sensor will propel the advancement of easily disposable pressure sensors and green paper-based flexible electronic devices.

A simple, instrument-free, paper-based analytical device with dual-emission carbon dots (CDs) (blue CDs and red CDs) was developed for the semiquantitative, visual, and sensitive speciation analysis of lead ions in a real sample with a sensitive detection limit of 2.89 nM. When a paper strip was immersed into the sample solution, the blue fluorescence was quenched by Pb2+ in solution, while the red fluorescence served as a background reference without color change, and significant color evolutions from blue to red were observed under the ultraviolet lamp, resulting in a semiquantitative visual detection. Furthermore, a smartphone was used in the visual detection of lead ions by identifying the RGB value of the fluorescent probe solution and corresponding paper strip. The application of smartphones and fluorescent paper strips has greatly shortened the detection time and reduced the cost of detection, providing a new strategy for the on-site and semiquantitative detection of heavy-metal ions in water samples.

There is a high interest in nanomaterials that effectively deactivate different types of bacteria and provide alternatives to chemical substances and antibiotics. This research is reporting the antibacterial performance in contaminated water of flexible structures consisting of thin metallic films deposited on water filter paper. Coatings were performed at low temperatures using high vacuum direct current (DC) magnetron sputtering deposition. The effectiveness of different metallic nanoparticles in functionalizing the fibrous surfaces and deactivating bacteria from water was tested during the experiment. The surface morphology of coated filter paper was characterized using digital optical microscopy and scanning electron microscopy (SEM). The fibrous substrates provided large area of exposure for metals to bacteria. X-ray diffraction and Energy Dispersive X-ray Spectrometer (EDS) were used to identify the chemical composition of the structures. The antibacterial performance was evaluated against Escherichia coli (E-coli) and total coliforms using the standardized membrane filtering technique for water and wastewater examination. Silver and copper effectively deactivate coliforms from water with copper providing higher performance. The antibacterial effect of copper and silver coatings with different thicknesses as well as the nanolayered combination of the two metals was also investigated. It was observed that coatings remained adherent to substrates and the antibacterial performance was maintained over consecutive exposures.

Development of recoverable and sustainable catalysts for environmental remediation still remains a great challenge. Here, we report a simple approach to immobilizing polyethylenimine (PEI)-templated silver nanoparticles (Ag PTNPs) onto the surface of cellulose filter paper for catalytic applications. First, branched PEI was utilized as a template to complex Ag(I) ions, then, sodium borohydride was applied as a reducing agent to generate Ag PTNPs. Thereafter, the formed Ag PTNPs were assembled onto filter paper via electrostatic interaction. The developed Ag PTNP-immobilized filter paper was characterized through different methods. We show that Ag PTNPs with a mean diameter of 4.6 ± 1.3 nm are able to be immobilized onto the surface of filter paper, and the Ag paper displays a remarkable catalytic activity and reusability towards the catalytic transformation of 4-nitrophenol to 4-aminophenol. The developed approach may be extended for the production of different kinds of NP-immobilized filter paper for the applications in sensing, environmental remediation, and biomedicine.

Developing a facile, cost-saving, and environment-friendly method for fabricating a multifunctional humidity sensor is of great significance to expand its practical applications. However, most humidity sensors involve a complex fabrication process, resulting in their high cost and narrow application fields. Herein, a multifunctional paper-based humidity sensor with many advantages is proposed. This humidity sensor is fabricated using conventional printing paper and flexible conductive adhesive tape by a facile pasting method, in which the paper is used as both the humidity-sensing material and the substrate of the sensor. Owing to the moderate hydrophilicity of the paper and the rational structure design of the paper-based humidity sensor, the sensor exhibits an excellent humidity-sensing response of more than 103 as well as good linearity ( R2 = 0.9549) within the humidity range from 41.1 to 91.5% relative humidity. Furthermore, the paper-based humidity sensor has good flexibility and compatibility, endowing it with multifunctional applications for breath rate, baby diaper wetting, noncontact switch, skin humidity, and spatial localization monitoring. Although the resistance of the paper-based humidity sensor is relatively large, the humidity-sensing response signals of the sensor can be conveniently processed by the designed signal processing system. The readily available starting materials and facile fabrication technique provide useful strategies for the development of multifunctional humidity sensors.

Hairy cellulose nanocrystalloids (HNC) are a brand new family of nanocellulose characterized by having functionalized amorphous poles joined by a crystalline shaft. In this paper we hypothesize that cationic HNC (CNCC) could be used as an effective retention agent in papermaking. To investigate this, we first flocculated a suspension of only fillers, namely kaolinite and CaCO3, and second, a suspension of recycled fibers, with CNCC. It was monitored by photometric dispersion analysis and laser focused beam reflectance. The flocculation mechanism was assessed by means of zeta potential, reflocculation efficiency, flocculation stability and optical microscopy. Finally, the effect of CNCC on drainage, retention and paper mechanical properties was studied. CNCC were found to heteroflocculate fillers at a wide range of dosages, finding a maximum floc size at a dosage of 30 mg/g. On the other hand, the maximum floc size when flocculating the pulp suspension, was found at a lower CNCC dosage (20 mg/g). In this case, fillers were being attached to the exterior surface of the fibers. In both systems, the maximum size increment was observed at the isoelectric point, so a charge neutralization mechanism was proposed. The addition of CNCC not only improved filler retention, but also pulp drainage by reducing these times. Moreover, although mechanical properties of the handsheets were affected by the presence of CNCC, this effect was much lighter than that caused by traditionally used retention systems. Hence, CNCC could replace many additives used in the wet-end of a paper machine, thus simplifying its operation.

This work describes a method to fabricate three-dimensional paper microfluidic devices in one step, without the need of stacking layers of paper, glue, or tape. We used a nontransparent negative photoresist that allows patterning selectively (vertically) the paper, creating systems of two or three layers, including channels. To demonstrate the capabilities of this methodology, we designed, fabricated, and tested a six-level diluter. The performance of the device was also simulated using a simple numerical model implemented in the program PETSc-FEM. The resulting μPAD is small (1.6 cm × 2.2 cm), inexpensive, requires low volumes of sample (5 μL), and is able to perform mixing and dilution in 2 min. Fil: Mora, Maria F.. Harvard University; Estados Unidos Fil: Garcia, Carlos D.. CLEMSON UNIVERSITY (CLEMSON UNIVERSITY); Fil: Schaumburg, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Kler, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina Fil: Berli, Claudio Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Hashimoto, Michinao. Harvard University; Estados Unidos Fil: Carrilho, Emanuel. Universidade de Sao Paulo; Brasil. Harvard University; Estados Unidos

In the last years, the imprinting technology has raised attention and different polymers with artificial recognition sites towards a target molecule have been developed. In this article, a polymerization-free method ―which only requires the dissolution of nylon-6 polymer and its subsequent incubation with the template molecule― has been employed for the preparation of a molecularly imprinted polymer directly immobilized on filter paper, thus increasing the versatility and manageability of the new material. The molecularly imprinted paper-based analytical device (MIP PAD) has been coupled to a fluorimeter via a custom-built platform, which enables direct measurement of the fluorescence at the surface of the MIP PAD. Extraction efficiency of the MIP PAD was evaluated using quinine as model analyte, measuring the fluorescence directly at the MIP PAD surface after incubation on aqueous standards of quinine and soda drink, showing that the performance of the imprinted material was superior to that of the non-imprinted polymer. In addition, the selectivity of the MIP PAD versus analogous organic fluorescent molecules has been further evaluated using norfloxacin, observing that the molecular imprinting results in selective extraction of quinine. The performance of the method has been evaluated for quantitative analysis, achieving limits of detection (LOD) and quantification (LOQ) for aqueous standards of 0.37 and 1.24 mg L−1, respectively, while in the case of spiked soda drink the LOD and LOQ were 0.63 and 2.11 mg L−1, respectively. The reproducibility of the measurements was also evaluated, observing values within range 2.30 and 9.07% measured as relative standard deviation.

The direct coating of graphene sheets obtained by electrochemical exfoliation on commercial paper renders the preparation of highly conductive flexible paper substrate for subsequent deposition of polyaniline (PANi) nanorods via electrochemical polymerization. The deposition of PANi can be well-controlled by adjusting the electrochemical polymerization time, leading to the formation of PANi coated graphene paper (PANi-GP). The as-prepared electrode exhibited high areal capacitance of 176 mF cm−2 in three-electrode system at a current density of 0.2 mA cm−2, which is around 10 times larger than that of pristine graphene paper due to the pseudocapacitive behavior of PANi. In-situ Raman test was used to determine the molecular changes during redox process of PANi. More importantly, all-solid-state symmetric capacitor assembled with two PANi-GP electrodes in a polymer electrolyte delivered an areal capacitance of 123 mF cm−2, corresponding to an areal energy density of 17.1 µWh cm−2 and an areal power density of 0.25 mW cm−2. The symmetric capacitor held a capacitive retention of 74.8% after 500 bending tests from 0 to 120°, suggesting the good flexibility and mechanical stability. These results showed the great promising application in flexible energy-storage devices.

The present work focused in assessing the hydrogen production from pretreated wastes of the paper industry (PIW) by simultaneous saccharification and fermentation (SSF) using anaerobic biofilms developed in natural fibers (ixtle) at different conditions. Anaerobic sludge from brewery wastewater treatment was used for biofilms and they were developed in plastic spheres covered with fiber cord from ixtle. The solid wastes of paper industry were previously pretreated with H2SO4 at 2.5% (v/v) at 120 °C by 30 min. The solids pretreated were hydrolyzed and fermented in batch reactors. All reactors were kept at an initial pH of 5.0 and three levels of enzyme loadings (10, 40 and 70 FPU/mL) and temperatures (35, 45, 55 °C) were assessed. The maximum hydrogen obtained (60.75 mmol/h*g volatile solids) was at 45 °C and 70 FPU/mL, moreover, no methane was detected in all cases.

We investigated treatment of cellulose paper with a phosphoric acid–urea solution for increasing the wet strength. First, a filter paper was immersed in a phosphoric acid–urea solution (phosphoric acid: urea mole ratio = 1:0, 3:1, 1:1, or 1:3). Next, the filter paper was put between glass plates and heated at 80–140 °C for 15 min to 3 h. Then, the filter paper was washed for 1 h in distilled water. After washing, the filter paper was dried in a hot press at 110 °C and 1.1 MPa for 1 h. We investigated disintegration by immersing the prepared filter papers in distilled water. The paper treated with the 1:3 phosphoric acid–urea solution did not disintegrate. The optimum concentrations for developing the wet strength of the paper were 1.2–2.5 M phosphoric acid and 3.7–7.5 M urea. The optimum treatment time and temperature were 1.5 h and 140 °C, respectively. The wet strength of the paper increased after treatment with the phosphoric acid–urea solution. This method is a viable alternative to treatment with chemicals such as polyamidoamine epichlorohydrin.

International audience; Despite its millennial age, cellulose paper remains the preferred material for domestic and professional printings, covering applications from simple office paperwork to fiducial solutions such as bills, passports, and head letters. The creation of robust photochromic patterns on cellulose papers for anti-counterfeiting applications is an important and still partially unaddressed challenge. In this contribution, we report the covalent printing of dibenzothienylethenes as photochromic compounds through a spatially-controlled light mediated thiol-X ligations. Photophysical and theoretical studies provide evidences for a reversible photochromism behavior, not affected significantly by the polar environment of the cellulose matrix, and demonstrates a high fatigue resistance over 18 successive write-erase cycles. The strong coloration-discoloration switch can be easily followed by a direct nakedeye readout.

High-capacity electrode materials are critical for portable electronic equipment that requires a high-energy density from lithium ion batteries (LIBs). Many different materials and fabrication methods for such electrodes have been developed for this purpose. Carbon paper coated with recycled silicon powder (CP-RSP) was prepared by coating silicon and pitch powder on the carbon paper, followed by stabilization at 250 °C in air and carbonization at 1000 °C in N2. The CP-RSP acted as both the current-collector and the active material for the anodes of LIBs. Electrodes with 2.5, 5, and 10 wt.% silicon exhibited capacity increases of 94, 129 and 41%, respectively, compared with the silicon-free electrode. The electrode for the CP-RSP with 5 wt. % silicon exhibited an optimal balance between discharge capacity and stability in long-cycle tests under various charging rates.