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A green and simple approach was demonstrated to prepare reduced graphene oxide (rGO) paper using Zn powder in ammonia solution as the reducing system at room temperature and GO paper obtained via vacuum filtration of GO aqueous dispersion as precursor. The effect of immersing time in the system, morphology and structure on the resulting rGO paper were investigated by X-ray diffraction, scanning and transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and capacitive behavior. Results showed that the rGO-60 paper (reduced for 60 min) displayed superior capacitive performance with high specific capacitance (130 F/g) as compared with other rGO papers under various treating times. The reduction time plays a key role in the morphology, structure, reduction degree and capacitive performance.

This paper studies the second-order coding rates for memoryless channels with a state sequence known non-causally at the encoder. In the case of finite alphabets, an achievability result is obtained using constant-composition random coding, and by using a small fraction of the block to transmit the empirical distribution of the state sequence. For error probabilities less than 0.5, it is shown that the second-order rate improves on an existing one based on independent and identically distributed random coding. In the Gaussian case (dirty paper coding) with an almost-sure power constraint, an achievability result is obtained using random coding over the surface of a sphere, and using a small fraction of the block to transmit a quantized description of the state power. It is shown that the second-order asymptotics are identical to the single-user Gaussian channel of the same input power without a state.

The appearance or printing quality of paper surfaces is mostly characterized by their glossiness, measured with a glossmeter as specular reflectance. The gloss properties of a base paper substrate can be improved after application of a poly(styrene-co-maleimide) nanoparticle coating under pure conditions or in the presence of different vegetable oils. The specular gloss properties of 11 different nanoparticle paper coatings have been determined under 75 degrees and 85 degrees incident light angles, with good relation between values along parallel (machine) and perpendicular (transverse) direction. The gloss properties for the different coatings have been further related to the surface topography. Therefore, the statistical and spatial surface roughness parameters have been studied in detail at two length scales including non-contact profilometry (1 x 1 mm(2)) and atomic force microscopy (2 x 2 m(2)). Based on values of the Rayleigh parameter for non-contact profilometry, the surfaces can be considered as optically rough. The gloss values cannot be directly related to statistical surface roughness parameters. Otherwise, an experimental power-law model for gloss has been proposed as a function of (/Sq) with correlation length and root-mean-square roughness Sq. A best-fit model illustrates that gloss properties of various nanoparticle paper coatings mainly relate to the spatial surface roughness parameters determined from non-contact profilometry. (c) 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 596-610, 2016

As a powerful analytical tool of molecular detection, surface-enhanced Raman spectroscopy (SERS) has attracted great attention in varied fields. However, it has seriously impeded the development of SERS that the preparation process is generally complicated and traditional substrates lack eco-friendliness, economy and flexibility. Herein, we fabricated the inkjet-printed paper-based semiconducting SERS substrates for the first time via an inexpensive office inkjet printer with representative two-dimensional MoO3-x nanosheets ink. Compared with conventional substrates, these paper-based semiconducting substrates not only could meet the requirements of simple and large-scale preparation, but also realize efficient sample collection by merely swabbing the surface. We obtained the detection limit concentration of rhodamine 6G as low as 10-7 M. Furthermore, these flexible paper-based substrates were successfully applied to detect crystal violet and malachite green on the fish surface by swabbing. With immense potentiality in practical applications, the inkjet-printed paper-based semiconducting SERS substrates are expected to open a new prospect for SERS.

Procalcitonion (PCT) have been proved to be disease-related markers of premature rupture of membranes (PROM) in serum of patients. Therefore, the profiling technology of rapid and sensitive is crucial for detecting the level of PCT in human serum, which is of great significance for early diagnosis and treatment of PROM. In this work, the surface-enhanced Raman scattering (SERS) detection platform combined with double antibody sandwich method was used to quantitatively detect PCT in serum of patients with PROM. A highly sensitive, uniform, and reliable SERS substrate was fabricated by assembling Ag nanowires (AgNWs) on the hydrophobic filter paper treated with alkyl ketene dimer (AKD). Then hollow Au nanocages (HAuNCs) with SERS activity were synthesized facilely. The SERS immunoassay system consists of SERS tags and capturing substrate. HAuNCs labled anti-PCT (labeling) were used as SERS tags. Filter paper modified with AgNWs and anti-PCT (coating) was used as capturing substrate. When the SERS immunoassay system were used to directly detect PCT antigen, Raman intensity at different PCT antigen concentrations (1 pg/mL-1 μg/mL) was linearly related to the logarithm of PCT antigen concentration. By establishing a calibration curve within a certain range, it can be concluded that the detection limits of PBS and human serum were as low as 2.86 pg/mL and 3.74 pg/mL respectively. Serum samples from PROM patients were detected by SERS, and the results were consistent with those of the enzyme-linked immunosorbent assay (ELISA). Furthermore, The high reproducibility and homogeneity of SERS immunoassay were confirmed. Above results demonstrated the feasibility and great potential for developing this new SERS immunosensor into a clinical tool for sensitive analysis of biomarkers in human serum.

A novel hydrophobic-SERS substrate platform based on silver nanoparticles (AgNPs) functionalized commercially available filter paper was reported. Compared with conventional substrates, not only could this novel SERS substrate meet the requirements of simple and large-scale preparation, but also realized direct droplet-detection with reusable property. In this work, the fabrication, physical characterization, and SERS sensitivity of the substrates to spot-on food determination were studied. The experimental results show the method exhibited high reproducibility with less than 9% spot-to-spot variation in Raman intensity. Furthermore, the method was successfully applied to detect melamine in diluted milk with the instrument detection limit (IDL) down to 1 ppm in a linear correlation (1 ppm–1000 ppm). In addition, this SERS substrate could also be applied successfully in other fields, such as the determination of pesticide (thiram) and dye (malachite green) in real environment.

This study demonstrates a novel strategy for colorimetric/surface-enhanced Raman scattering (SERS) dual-mode sensing of sulfur dioxide (SO2) by coupling headspace sampling (HS) with paper-based analytical device (PAD). The smart and multifunctional PAD is fabricated with a vacuum filtration method in which 4-mercaptopyridine (Mpy)-modified gold nanorods (GNRs)-reduced graphene oxide (rGO) hybrids (rGO/MPy-GNRs), anhydrous methanol, and starch-iodine complex are immobilized into cellulose-based filter papers. The resultant PAD exhibits a deep-blue color with a strong absorption peak at 600 nm due to the formation of an intermolecular charge-transfer complex between starch and iodine. However, the addition of SO2 induces the Karl Fischer reaction, resulting in the decrease of color and increase of SERS signals. Therefore, the PAD can be used not only as a naked-eye indicator of SO2 changed from blue to colorless but also as a highly sensitive SERS substrates because of the SO2-triggered conversion of Mpy to...

In the present work, highly sensitive Raman detection of nitenpyram using superhydrophobic filter paper as substrates is introduced. The process is simple, and efficient. By sequentially coating silver dendrites and Octyltrimethoxysilane (OTMOS) on filter paper, we produced highly active surface-enhanced Raman scattering (SERS) substrates which show advancing and receding water contact angles of θA/θR = 159°/156°. Nitenpyram, a type of pesticides popularly used in agriculture, can be easily detected with the detection limit as low as 1 nM using the superhydrophobic filter paper as SERS substrates, which validates their use in Raman applications.

Direct functionalization of prefabricated free-standing graphene oxide paper (GOP) is the only approach suitable for systematic tuning of its mechanical, thermal and electronic characteristics. However, the traditional liquid-phase functionalization can compromise physical integrity of the paper-like material up to its total disintegration. In the present paper, we attempted to apply an alternative, solvent-free strategy for facile and nondestructive functionalization of GOP with 1-octadecylamine (ODA) and 1,12-diaminododecane (DAD) as representatives of aliphatic amines, and with 1-aminopyrene (AP) and 1,5-diaminonaphthalene (DAN) as examples of aromatic amines. The functionalization can be carried out under moderate heating at 150–180 °C for 2 h in vacuum, and proceeds through both amidation and epoxy ring opening reactions. Comparative characterization of pristine and amine-modified GOP samples was carried out by means of Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopy, thermogravimetric and differential thermal analysis, scanning electron and atomic force microscopy. In addition, we compared stability in water, wettability, electrical conductivity and elastic (Young's) modulus of GOP samples before and after functionalization. The highest content of amine species was obtained in the case of GOP-ODA, followed by GOP-DAD, GOP-AP and GOP-DAN. The functionalization increased mechanical and thermal stability, as well as the electrical conductivity of GOP. The magnitude of each effect depends on the structure of amine employed, which allows for tuning a given GOP characteristic. Morphological characterization showed that, compared to pristine graphene oxide paper, amine-modified mats become relatively ordered layered structures, in which individual GO sheets are organized in a near-parallel fashion.

We construct a multiplex surface-enhanced Raman scattering (SERS) platform based on a plasmonic paper substrate and a double-labeled probe for the detection of multiple fluorescent dyes at high sensitivity in a single-wavelength light source system. Plasmonic paper, made of silver nanodots on three-dimensional cellulose fibers, enables highly sensitive SERS biosensing based on localized surface plasmon resonance (LSPR). The proposed method enables the identification and quantification of a range of fluorescent dyes ranging from picomolar to millimolar concentrations. The use of 5' fluorescent dyes and 3' biotin-modified probes as SERS-coded probes renders possible the separation of fluorescent dyes with streptavidin-coated magnetic beads (SMBs) and the sensitive detection of multiple dyes after the reverse transcription polymerase chain reaction (RT-PCR). This experimental study reveals the multiplex detection capability of PCR-based SERS under existing PCR conditions without modifying primer and probe sequences. The combination of magnetic bead-based separation and paper SERS platform is efficient, economical, and can be used for the simultaneous detection of two or more pathogens.

_A 5-minute video demonstration of this paper is available at this YouTube link._ PREAMBLE A variety of research on human cognition demonstrates that humans learn and communicate best when more than one processing system (e.g. visual, auditory, touch) is used. And, related research also shows that, no matter how technical the material, most humans also retain and process information best when they can put a narrative "story" to it. So, when considering the future of scholarly communication, we should be careful not to do blithely away with the linear narrative format that articles and books have followed for centuries: instead, we should enrich it. Much more than text is used to communicate in Science. Figures, which include images, diagrams, graphs, charts, and more, have enriched scholarly articles since the time of Galileo, and ever-growing volumes of data underpin most scientific papers. When scientists communicate face-to-face, as in talks or small discussions, these figures are often the focus of the conversation. In the best discussions, scientists have the ability to manipulate the figures, and to access underlying data, in real-time, so as to test out various what-if scenarios, and to explain findings more clearly. THIS SHORT ARTICLE EXPLAINS—AND SHOWS WITH DEMONSTRATIONS—HOW SCHOLARLY "PAPERS" CAN MORPH INTO LONG-LASTING RICH RECORDS OF SCIENTIFIC DISCOURSE, enriched with deep data and code linkages, interactive figures, audio, video, and commenting.

Accurate, sensitive, and selective on-spot screening of volatile aldehydes as lung cancer biomarkers is of vital significance for preclinical diagnosis and treatment guidance of cancers. However, the common methods of sensing biomarkers are limited by the fact that they are time-consuming, require professional personnel, and have complex matrixes. Here, we developed a smart vapor generation paper-based thin-film microextraction system capable of both sensitive on-field fluorescence detection and accurate surface-enhanced Raman spectroscopy (SERS) quantification of volatile benzaldehyde (BA) by utilizing stimuli-responsive core-shell gold nanorod (GNR) quantum dot (QD)-embedded metal-organic framework (MOF) structures. The amino-modified GNRs and carboxyl-capped QDs can directly assemble with each other by electrostatic interaction, which leads to an almost complete emission quenching of QDs. The addition of BA molecules destroys the GNRs-QD assemblies due to the Schiff base reactions between the amine group of 4-mercaptonoaniline and the aldehyde moiety of BA, resulting in the increase of the fluorescence and Raman signal of hybrid systems, which enables the visualization of BA with the naked eye. Moreover, the "cavity-diffusion" effect of porous MOF shells validates the selective concentration of gaseous BA molecules on the GNR surface, allowing the discrimination of BA in exhaled breath rapidly and precisely even at the sub-ppb level with excellent specificity against other volatile organic compounds. This study not only offers a versatile sensing platform for accurate discrimination of lung cancer from controls but also opens an avenue for the design of smart sensors for point-of-care applications.

Many limitations hinder the practical applications of surface-enhanced Raman spectroscopy (SERS) substrates on the detection of real-world samples, such as collection efficiency for solid samples, separation and preconcentration for liquid ingredient. In this study, polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) were decorated on the surface of AgNP-based filter paper via a simple process. PSS-functionalized paper SERS substrates were utilized for rapid separation, preconcentration and detection of colorants in drinks with complex components. Compared with conventional rigid SERS substrates, separation, preconcentration of analytes can be realized by a surface chemical gradient and electrostatic interaction created by polyelectrolyte coating-paper. Synthetic dyes, such as sunset yellow and lemon yellow were separated and detected successfully in drinks by PSS-functionalized paper SERS substrates. Owing to the low cost, simple preparation process and high separation and preconcentration for the samples, PSS-functionalized paper substrates are promising to be used in solving critical problems for separation and detection of real-world samples.

Fourier transform infrared (FTIR) spectroscopy is ideally suited to the cultural heritage sector due to the ability to apply it minimally or non-destructively with limited sample preparation, fast analysis times (spectra can be obtained in a matter of minutes), relatively low cost, and relative ease of use. FTIR has been applied to answer a range of archaeological research questions through analysis of both organic and inorganic materials. Examples include determining the firing temperatures of archaeological clays or identifying types of textile.

The extraordinary graphene material has brought about extensive attention in space engineering for outstanding characteristics. The reduced graphene oxide paper (rGOP) was irradiated by 500 keV proton in a ground-based irradiation simulator. The results show that the spacing of layer to layer was increased after irradiation, while the oxygen functional group was decreased. The result of XPS and Raman spectroscopy indicates that the sp3 carbon and defects increased, and the disorder structure in high fluence irradiated materials also increased. Furthermore, the performance degradation for thermal stability and electrical property of rGOP is contributed to the combination of defects and disordered structure.

Let l be a Banach sequence space with a monotone norm in which the canonical system (e_{n}) is an unconditional basis. We show that if there exists a continuous linear unbounded operator between l-K\"{o}the spaces, then there exists a continuous unbounded quasi-diagonal operator between them. Using this result, we study in terms of corresponding K\"{o}the matrices when every continuous linear operator between l-K\"{o}the spaces is bounded. As an application, we observe that the existence of an unbounded operator between l-K\"{o}the spaces, under a splitting condition, causes the existence of a common basic subspace.

In this study, we report a flexible transparent freestanding surface-enhanced Raman scattering (SERS) platform composed of 2,2,6,6-tetramethylpiperidine-1-oxy-oxidized cellulose nanofibers (TEMPO-C...

In this note we address the attempted proof of the existence of static solutions to the Einstein-Vlasov system as given in \cite{Wol}. We focus on a specific and central part of the proof which concerns a variational problem with an obstacle. We show that two important claims in \cite{Wol} are incorrect and we question the validity of a third claim. We also discuss the variational problem and its difficulties with the aim to stimulate further investigations of this intriguing problem: to answer the question whether or not static solutions of the Einstein-Vlasov system can be found as local minimizers of an energy-Casimir functional., Comment: 9 pages

Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping.

A facile and cost-effective method was developed to create superhydrophobic surfaces onto a superhydrophilic commercial paper for the application of droplet splitting of microliter droplets into nano and sub-nano-liter droplets. The high wettability contrast of nearly 180° between the superhydrophobic region created via candle soot coated onto the patterned poly (dimethylsiloxane) and the paper causes the self-partitioning of a 1 µl droplet while sliding through the surface with a speed ranging from 0.001 to 7.3 mm/s. Additionally, the splitting of the droplet demonstrated for µl droplets of surface tension ranging from 72 mN/m to 38.5 mN/m. The plasmonic droplet assay for surface-enhanced Raman spectroscopy was fabricated via in-situ reduction of Ag nanoparticles onto the superhydrophilic region. The Raman scattering studies of methyl orange using the prepared substrates exhibit a limit of detection of 670 pM. Further, by using methyl orange as a probe molecule, selective detection of Hg2+ ions up to a concentration of 100 pM in nanoliter droplet volume is demonstrated. It is envisaged that these cost-effective plasmonic nanoliter droplet assays created via patterned superhydrophilic-superhydrophobic can find applications in high throughput screening, microfluidic bioassays, medical diagnosis.

This study aimed to investigate the effects of temperature and aging on the characteristic parameters of dielectric spectra of epoxy resin impregnated paper insulation. A broadband dielectric spectra test platform was established and an equivalent physical model of the valve side dry-type bushing of the converter transformer was developed. Different degrees of thermal aging were performed at 130 °C for 0, 4, 8, 16, and 32 days. In addition, variation of the complex permittivity and dielectric loss factors of epoxy resin impregnated paper at different temperatures and different degrees of aging was revealed. The dielectric spectra test results were fitted using the Havriliak-Negami (HN) relaxation model. The characteristic parameters were extracted, and the influences of temperature and aging on the characteristic parameters of the HN model were analyzed. The results show that in the low frequency range, temperature and aging exert greater influences on the complex permittivity. In the high frequency range, temperature and aging have smaller effect. The relaxation time and temperature satisfy the relationship of the Arrhenius equation, and the relaxation strength increases exponentially with increasing temperature. The relaxation time τ, the relaxation intensity Δe, the shape parameter α, and the shape parameter β can characterize the aging degree of paper insulation. A linear relationship between relaxation and aging times, and an exponential relationship between relaxation intensity and aging time were revealed.

Patients with hypertension are seriously affected by Parkinson’s disease than patients with normal blood pressure. Thus, early detection of hypertension and Parkinson disease by monitoring subtle changes in specific biomarkers from body fluids can minimize the risk. This paper proposes a flexible, portable paper-based sensor for simultaneous electrochemical sensing of dopamine and uric acid, using differential pulse voltammetry and electrochemical impedance spectroscopy on electrodeposited Prussian blue on carbon dots@graphite paper. The characteristic peaks of dopamine and uric acid in the differential pulse voltammogram are well separated. Further surface characterization of Prussian blue/carbon dots@graphite paper was carried out by Raman Spectra and Scanning Electron Microscope (SEM). The proposed sensor promoted the fast electrochemical detection of dopamine and uric acid with the linear response for concentrations from 0.2–920.0 μM with a limit of detection 0.015 μM, respectively in an aqueous sample. Excellent flexing stability is demonstrated by the proposed sensor, which can maintain its initial current after being bent more than 300 times.

The study investigates the use of copy paper in poly (butylene adipate terephthalate)-PBAT and polylactide-PLA composites. The influence of paper volume fraction (21, 30 and 48%) on the void content and the composite properties was analysed by using two different compression moulding methods. An increasing fibre content lead to significantly improved tensile characteristics, while the Charpy impact strength showed a toughness decrease for PBAT and an increase for PLA composites. Additionally, layered composites, where either two stiff PLA composite layers enclosed a ductile PBAT composite core or vice versa, were produced with the aim to increase the toughness. Due to the high elongation of PBAT, the insufficient fibre/matrix adhesion and the low fibre length, this goal could not be reached. However, copy paper represents a good reinforcing component achieving a maximum strength of 120 MPa and a tensile modulus of 10.2 GPa at the highest paper volume fraction in PLA.

Surface enhanced Raman scattering (SERS) substrates that can be attached to rough, irregular surfaces and directly collect samples is especially useful for the detection of surface organic residues. Herein, novel AuNPs-pseudo-paper films (APPFs) with uniform structure, flexible properties and wicking capabilities were first fabricated and used as SERS substrate for the sensitive detection of surface pesticides residues. Gold nanoparticles (AuNPs) were in situ synthesized on pseudo-paper films (PPFs) by iterative seeding method to create lots of “hot-spots”, accordingly exhibiting high SERS activity (SERS enhancement factor of 3.02 × 106). By virtue of polyethylenimine (PEI) grafted onto the dissolved microcrystalline cellulose (MCC), AuCl4- and AuNPs can firmly be bonded to the surfaces of PPFs. The prepared APPFs show high reproducibility (relative standard deviation of 6.13%), which is attributed to the uniform surface of the films. The fabricated APPFs SERS substrate allows rapid detection of surface pesticides residues by a facile “swabbing-measure” detection mode avoiding tedious and time-consuming sampling and separation processes. Based on their inherent SERS spectra, thiram, parathion methyl, and malachite green (MG) can be simultaneously detected on apple peel, which demonstrates the potential applicability of this developed protocol for surface organic residues analysis in agriculture and food security.

Damage to paper (sulfate pulp, cotton half-stuff, and flax half-stuff) caused by the Aspergillus niger, A. sclerotiorum, and Penicillium chrysogenum fungi is investigated by Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy. It is shown that the use of application infrared Fourier-transform absorption spectroscopy allows one to identify the initial stages of damage from a decrease in the degree of crystallinity of the cellulose contained in paper. The absorption band near 900 cm–1 is used as an indicator of early stages of damage. An increase in the amide II peak at 1550 cm–1 and spectral changes in the region of valence vibrations of the C–H bonds (2800–3000 cm–1) are observed in the case of heavier damage. The obtained data indicate that the vibrational spectroscopy techniques are promising in the study of damage of archive documents.

History has been kind to Christian Bohr (1855–1911). His name is attached eponymously to three different areas of respiratory physiology. The first is the Bohr dead space, which refers to the portion of the tidal volume that does not undergo gas exchange. The second is the increase in oxygen affinity of hemoglobin caused by the addition of carbon dioxide to the blood. This is known as the Bohr effect and is a very important feature of gas exchange, both in the lung and in peripheral tissues. Both of these contributions by Bohr are familiar to most students. Bohr’s third contribution refers to the calculation of the changes in the Po2 of blood as oxygen is loaded in the pulmonary capillary, the so-called Bohr integration. This contribution is less well known now, partly because of the advent of digital computing, but it was important in its day. The analysis is challenging because the very nonlinear shape of the oxygen dissociation curve means that the Po2 difference between the alveolar gas and the capillary blood, which is the driving pressure for diffusion, changes in a complicated way. All three papers are in German, and two of them are long and tedious to read. English translations are available, but few people read the papers, despite the fact that the first two articles are very frequently cited. In the present article, Bohr’s contributions are reviewed, and some parts of the articles that are particularly difficult to understand are clarified.

Recent progress towards the development of lightweight, flexible, wearable, and foldable portable electronics has promoted the increasing demand for high-performance substrates. However, eco-friendly materials with low cost and remarkable performance are still under investigation. In this study, a kind of lightweight, flexible, and electrically conductive multi-walled nanotube (MWCNT) and a few layered graphene (GR) reinforced hybrid recycled papers were obtained by a facile and scalable papermaking process. The influence of nanofiller type and concentration on the mechanical, electrical, thermal performance of the nanocomposite paper were investigated. Fourier transform infrared spectroscopy and Raman spectroscopy revealed the formation of molecular interactions between the MWCNTs, GR, and the cellulose fibers. Scanning electron microscopy proved the continuous network of nanofiller phase within the cellulose matrix. Tensile tests revealed that the tensile strength of MWCNTs reinforced recycled paper increased about 276%, while the GR reinforced recycled paper exhibited the highest Young modulus with 425% increase compared to the neat waste paper. The highest electrical conductivity was measured around 0.219 S/cm for the GR/CNT10 hybrid recycled paper. A positive synergetic effect of the MWCNTs and GR nanofillers was observed in the case of hybrid nanocomposite papers. More importantly, adjusting the microstructure of the waste paper with the introduction of carbon-based 1D/2D nanofillers led to higher improvement in the mechanical properties, electrical conductivity, thermal conductivity. These regenerated properties made the hybrid nanocomposite paper a promising substrate material with considerable potential applications for various flexible and portable electronic devices.

Carbon paper electrodes are employed for different electrochemical applications such as flow batteries and fuel cells. However, redox reactions such as VO2+/VO2+ in a vanadium redox flow battery have been found to possess relatively slow kinetics, resulting in significant activation losses during operation. In this work, we demonstrate a facile and scalable method for nitrogen doping of carbon paper electrodes, leading to superior electrocatalytic activity. The effects of pyrolytic pretreatments under different conditions on the performance of carbon paper were also studied to elucidate their electrocatalytic activity from a material physics perspective, using Raman spectroscopy. The 2D Raman signature, a specific feature of the carbon structures, was employed to understand the effect of different pretreatments on the Fermi level of the carbon papers, which could help us elucidate their intrinsic electron transfer kinetics. The full wave half-maximum of the 2D Raman band and the intensity ratio I2D/IG wer...

In this study, laboratory tissue paper and hardboard waste were utilized to synthesize activated carbon (AC). The structure, morphology, zeta potential and particle size of the synthesized AC is investigated using X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, zeta seizer and particle size analysis techniques. The synthesized AC is used as an adsorbent for removal of Methylene blue (MB) and chromium ion from aqueous solution. AC adsorption efficiency is analyzed using a UV–Vis spectrophotometer. The adsorption capacity of the tissue paper derived activated carbon (T-AC) is greater than that of the hardboard derived activated carbon (H-AC). MB adsorption by T-AC and H-AC data fitted well to the Langmuir isotherm model. The thermodynamic parameters such as Gibbs free energy (∆G), enthalpy change (∆H) and entropy change (∆S) are calculated for both the T-AC and H-AC adsorbents. Moreover, the dye adsorbed T-AC and H-AC exhibit good specific capacitance value of about 260 Fg−1 and 155 Fg−1 at a constant current density of 0.5 Ag−1. The specific capacitance is maintained to an extent of 92% and 71% even after 1000 cycles for T-AC and H-AC respectively. It is encouraging that the results obtained have opened up ways of utilizing laboratory waste materials for producing materials useful in environmental remediation and energy storage sectors.

A paper-based device is a promising technology for point-of-care testing (POCT). In this work, a novel fluorescent probe with red emission (650 nm) and a large Stokes shift (∼170 nm) for Cys detection was reported for the first time. This probe exhibited a highly selective and rapid response to Cys within 5 min. Importantly, by introducing this probe into microfluidic paper-based analytical devices (μPADs), a paper-based device was developed for simple, high-throughput and highly sensitive detection of Cys. Finally, satisfactory performance of this paper-based device for Cys detection was achieved in real samples, which indicates the great potential of our strategy in the construction of POCT systems for detecting analytes.

Annotated translations from Latin of three of the Euler’s papers on celestial mechanics are presented, which fall into the category of three-body problems. The first translation deals with an exact solution of three bodies that move around the common center of mass and always line up. This is considered the first work from which the three collinear Lagrange points could be obtained. The second translation deals with motions of Sun, Earth and Moon in syzygy and Moon libration as well, where, for the first time, Euler introduces an archaic form of a Fourier sine series expansion to describe the Moon’s wagging motion. The last translation relates to a paper that was written with the goal of alleviating astronomical computations of the perturbed motion of the Moon around the Earth by the Sun, ending up with eight coupled differential equations for resolving the perturbed motion of this celestial body. Despite showing great analytical skills, Euler gave no indications on how this system of equations could be solved, which renders his efforts practically useless in the determination of the variations of the nodal line and inclination of the Moon’s orbit.

This study explores the method of applying surface enhanced Raman scattering (SERS) in diagnosing the aging stage of oil-paper insulation equipment in the power system, which provides access to the on-line mornitoring of electrical equipment. Oil-paper samples in different aging stages were obtained by accelerated aging experiments. Effective Raman signals of insulating oil were collected by using the self-made hexagonal sliver nano-plates SERS substrates and the self-assembled Raman detection platform. For the SERS data of oil-paper insulation samples, kernel entropy component analysis (KECA) was applied to extract the Raman spectral features and support vector machine (SVM) was used to recognize the the aging stage of oil-paper insulation. The results demonstrate that the KECA-SVM method exhibits a good diagnostic capacity and the recognition accuracy of the propsed method reached 81.43 % (57/70). In summary, a new spectral method is proposed to diagnose the aging stage of oil-paper insulation, which lays a foundation for the actual diagnosis of the aging condition in running oil-paper insulation equipment by Raman spectroscopy.

This report describes the systematic combination of structurally diverse plasmonic metal nanoparticles (AgNPs, AuNPs, Ag core–Au shell NPs, and anisotropic AuNPs) on flexible paper-based materials to induce signal-enhancing environments for surface enhanced Raman spectroscopy (SERS) applications. The anisotropic AuNP-modified paper exhibits the highest SERS response due to the surface area and the nature of the broad surface plasmon resonance (SPR) neighboring the Raman excitation wavelength. The subsequent addition of a second layer with these four NPs (e.g., sandwich arrangement) leads to the notable increase of the SERS signals by inducing a high probability of electromagnetic field environments associated with the interparticle SPR coupling and hot spots. After examining sixteen total combinations, the highest SERS response is obtained from the second layer with AgNPs on the anisotropic AuNP paper substrate, which allows for a higher calibration sensitivity and wider dynamic range than those of typical AuNP–AuNP arrangement. The variation of the SERS signals is also found to be below 20% based on multiple measurements (both intra-sample and inter-sample). Furthermore, the degree of SERS signal reductions for the sandwiched analytes is notably slow, indicating their increased long-term stability. The optimized combination is then employed in the detection of let-7f microRNA to demonstrate their practicability as SERS substrates. Precisely introducing interparticle coupling and hot spots with readily available plasmonic NPs still allows for the design of inexpensive and practical signal enhancing substrates that are capable of increasing the calibration sensitivity, extending the dynamic range, and lowering the detection limit of various organic and biological molecules.

PEDOT:PSS organic printed electronics chemical interactions with the ink-receiving layer (IRL) of monopolar inkjet paper substrates and coating color composition were evaluated through Raman spectroscopy mapping in Z (depth) and (XY) direction, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Other evaluated properties of the IRLs were pore size distribution (PSD), surface roughness, ink de-wetting, surface energy and the impact of such characteristics on the electronics performance of the printed layers. Resin-coated inkjet papers were compared to a multilayer coated paper substrate that also contained an IRL but did not contain the plastic polyethylene (PE) resin layer. This substrate showed better electronic performance (i.e., lower sheet resistance), which we attributed to the inert coating composition, higher surface roughness and higher polarity of the surface which influenced the de-wetting of the ink. The novelty is that this substrate was rougher and with somewhat lower printing quality but with better electronic performance and the advantage of not having PE in their composite structure, which favors recycling. © 2019 The Royal Society of Chemistry., Knowledge Foundation; AForsk Foundation [18-281]; J. Gust. Richert Foundation [2018-00459]; Knut and Alice Wallenberg Foundation through the Wallenberg Wood Science Center; Swedish Graphic Companies Federation; Treesearch.se

Purpose – The purpose of this paper is to evaluate the performance of paper mill plant, which is a very key factor in improving its production. A number of safety challenges can be successfully fixed for a paper mill to continue to make further improvements in reliability, safety and economics. Many incidents in the paper mill plants are frequently caused by human error and equipment failure. Many of the incidents are generally based on poor managerial strategies. These types of errors could have been prevented if safety instructions had been correctly followed and supported in the maintenance system. Design/methodology/approach – A paper mill plant mainly consists four sections namely the head box, wire part, press part and dryer. All these four parts are connected in series configuration. The authors have developed a mathematical model for the plant in which power supply is in standby mode. The designed system can fail in five ways, i.e. by the failure of head box failure, wire part failure, press part failure, dryer failure and power (electricity) failure. So to make proper functioning of paper machine and no interruption in power supply, the authors have considered that power supply is in standby mode. Findings – Using the supplementary variable technique, the Laplace transformations and Markov process theory, the reliability indices of the paper mill plant model are determined. Originality/value – In the present paper, the authors have developed a mathematical model based on a paper plant machine.

Adhesive wear and thermal degradation are the main aging mechanisms of paper-based friction materials. However, how these aging mechanisms affect the tribological characteristics of such materials is not fully understood. In this paper, the respective influences of the two aging mechanisms on the tribological characteristics of the friction materials are investigated through simulation. It is assumed that adhesive wear pre-dominantly affects the surface topography, while thermal degradation significantly affects the mechanical properties of the friction material. The simulation results show that the static friction coefficient and both normal and tangential contact stiffnesses increase due to adhesive wear, but decrease due to thermal degradation. These trends are qualitatively in agreement with experimental observations reported in the literature and our previous work.

The high cost of regular diagnostic kits severely impeded its uses for routine clinical assay and fieldworks. A cost-effective chromatography paper is chemically modified with Ag nanostructures using the simple electroless silver deposition, producing a scalable and disposable substrate for surface-enhanced Raman spectroscopy, as well as a large scale of catalytic active sites over many chemical reactions. Synergetic measurement including surface-enhanced Raman spectroscopy and laser desorption ionization-mass spectrometry is performed on Ag decorated filter paper using a thiol containing compound as indicator, allowing for the acquisition of spatially correlated spectroscopy in the tandem mode. In addition, hydrophilic porous cellulose network that contains a certain amount of liquid naturally served as a chemical reactor for molecular transport and reaction. Positive results from catalytic reaction on metallized paper convincingly demonstrated that total microanalysis system on paper (μ-TASoP), as a compelling alternative would find a wide breadth of applications in developing disposable medical devices and customary laboratory assays. Copyright © 2015 John Wiley & Sons, Ltd.

Connectivity is the safety network for biodiversity conservation because connected habitats are more effective for saving the species and ecological functions. The nature of coupling for connectivity also plays an important role in the co-existence of species in cyclic-dominance. The rock-paper-scissors game is one of the paradigmatic mathematical model in evolutionary game theory to understand the mechanism of biodiversity in cyclic-dominance. In this paper, the metapopulation model for rock-paper-scissors with mutations is presented in which the total population is divided into patches and the patches form a network of complete graph. The migration among patches is allowed through simple random walk. The replicator-mutator equations are used with the migration term. When migration is allowed then the population of the patches will synchronized and attain stable state through Hopf bifurcation. Apart form this, two phases are observed when the strategies of one of the species mutate to other two species: co-existence of all the species phase and existence of one kind of species phase. The transition from one phase to another phase is taking place due to transcritical bifurcation. The dynamics of the population of species of rock, paper, scissors is studied in the environment of homogeneous and heterogeneous mutation. Numerical simulations have been performed when mutation is allowed in all the patches (homogeneous mutation) and some of the patches (heterogeneous mutation). It has been observed that when the number of patches is increased in the case of heterogeneous mutation then the population of any of the species will not extinct and all the species will co-exist.

Automation in every domain is today’s need, so in question paper setting also. The proposed system is automation of paper setting and identification of difficulty level of questions and question papers, which uses blooms taxonomy categorization to classify the questions in easy, medium and high categories. By using blooms taxonomy, the difficulty level of question can be identified, which is helpful in generating qualitative question paper. While categorizing questions, system uses natural language pre-processing techniques, which are understood by computer and also uses Latent Dirichlet Allocation algorithm. Based on paper setter’s requirement, paper setting is done; also, if user wants to check difficulty level of any question paper then this is also done by proposed system using NLP. The paper setting using difficulty measure is right benchmark for evaluating student’s efficiency. Automation of paper setting improves the speed, and difficulty level module improves the quality.

In this note we offer some criticism on the paper “On an identity for zeros of Bessel functions” by Baricz et al. [3] . The paper gives identities of type Stieltjes–Calogero for the sums of reciprocals of differences of fourth powers of zeros of Bessel functions. Although interesting in principle, by containing one too many sums of similar complexity the identities fail to convey the true spirit of the work of Stieltjes and Calogero. We rectify this by providing what we think is the correct type of identity for the above-said sums, in the general setup of entire functions of order

Mn3O4 nanoparticles were anchored on the surface of oxidised graphite paper via template-free hydrothermal method. Synthesized samples were characterized using different techniques such as X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), High Resolution Transmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy (XPS). Electrochemical capacitor behaviour was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The binder free material was found to exhibit a specific capacitance of 471 F g−1 at a current density of 1 mA cm−2 in 1 M Na2SO4. Conductive additive free, Mn3O4 anchored electrode was used as positive electrode in the asymmetric cell fabrication; the asymmetric cell was tested at a potential window of 1.6 V and its performance characteristics were evaluated. The asymmetric cell delivered a maximum specific energy of 47 Wh kg−1 at a power density of 202.5 W kg−1 which evidenced the superior performance of the synthesized electrode material. Here in the present work, the surface oxidised graphite paper was used as an excellent current collector and active sites for anchoring Mn3O4 due to its desirable properties.

The effect of variation of radio frequency (rf) power on the structural, optical and electronic properties of intrinsic hydrogenated amorphous silicon (a-Si:H) films deposited at very low substrate temperature (Ts) 110 °C were studied. These films were prepared varying rf power (40-70 W) on borosilicate glass, photo paper and c-Si substrates using rf-plasma enhanced chemical vapour deposition (13.56 MHz) technique. All films show amorphous structure confirmed by Raman measurement and also supported by spectroscopic ellipsometry (SE) measurements. SE results show that at higher rf power, amplitude of peak decreases and broadening increases due to increase in void density. Intrinsic layer with optimized rf power was used for fabricating n-i-p solar cell on flexible polyethylene terephthalate (PET), polyimide (PI), photo paper and rigid glass. The efficiency of solar cells fabricated on flexible PET and PI is 3.30% and 3.36%, which is close to 3.82% on rigid glass. In case of solar cells on photo paper, an efficiency of ~ 1.08% was obtained. The studies show that it is possible to fabricate a-Si:H based solar cells on photo paper and other substrates at very low Ts.

Practical production of conductive paper requires the balancing of high electrical conductance, thermal stability and tensile modulus, with cost effectiveness. By utilizing lignocellulose (3.85 ± 0.35% and 17.17 ± 0.62% lignin contents) and graphite as starting materials, a lignocellulose/reduced graphene oxide (LRGO) composite conductive paper is successfully fabricated. The free-standing LRGO paper has a low sheet resistance of 506 ± 34 Ω/sq with a graphene derivative content of ~ 20 wt%. Also high Tonset (312 °C) and T95 (251 °C) are observed, along with a tensile modulus up to 8.36 GPa if ten additional passes of microfluidization are used. Moreover, LRGO paper was used to make active electrodes for a supercapacitor that achieved a specific capacitance of 77.0 F/g. There has been minimal reporting of applying lignocellulose in conductive paper production, so this new method is anticipated to pave the way for developing advanced materials derived from low cost biomass.

The purpose of this paper is to examine what are the most important ideas of special relativity (SR) education from Einstein’s perspective, to reflect on the previous studies of special relativity education up to the present through Einstein’s ideas, and to give prospects for its future direction. We analyzed Einstein’s book, The Evolution of Physics, focusing on three questions: Why should we teach SR? What kinds of the content knowledge of SR should we teach? How should we teach SR? Based on this analysis, we formulated three criteria for SR education: (1) intrinsic value, (2) integral knowledge, and (3) hermeneutic/communicative approach. In addition, research papers on SR education published in South Korea were analyzed based on these criteria. As a result, we have found that many studies are very different from Einstein’s perspective on SR education. And we discussed that, despite the researchers’ intentions, their studies are likely to lead other research on SR and educational practices toward the opposite of Einstein’s emphasis (i.e., instrumental purpose, fragmentary content knowledge, and partial/functional approach). Finally, we suggest Einsteinian Physics Education as a new way to improve not only SR education but also physics education in general from Einstein’s perspective.

Hydrophobic paper decorated Ag nanoparticles (NPs) with a uniform distribution was fabricated in an oil-paper-aqueous triphasic system via a facile in situ interfacial reduction approach. Interestingly, the Ag NPs formed at the paper/aqueous interface could migrate to the oil/paper interface. Moreover, these Ag NPs would not continue to migrate away the paper surface into the oil phase but was completely confined in the solid paper matrix. This phase confinement of migrated Ag NPs in the paper matrix creates abundant 3D hot spots for plasmonic enhancement. The obtained Ag-loaded paper exhibits an excellent SERS activity, reliable reproducibility and autofluorescence suppression effect, which enabling it as a promising platform for qualitative and quantitative SERS study. Due to its condensation effect, the hydrophobic paper surface can be used as a concentrator to enrich water-soluble analytes over the SERS active domains for highly sensitive detection (10−9 mol/L−1). Furthermore, the Ag-loaded paper combined with the feature of chromatography and plamon-enhanced optical signals possesses ability to perform synchronous separation and surface-enhanced Raman scattering (SERS) detection of complex samples.

Paper-based SERS sensor has attracted considerable attention recently, resulting from the separation, aggregation and high sensitive detection of biomolecules. However, optical losses, caused by the holes or “vase”-like defects, affect the overall intensity of the electromagnetic (EM) coupling and then the Raman signal. Silver nanoflowers (AgNFs) connected with silver nanoparticles (AgNPs) arrays are proposed and firstly obtained onto such “vase” surface to enhance the EM coupling. AgNFs are easily self-assembled on the defects, and the closed packed AgNPs can be formed on the other area. Multiple cascaded amplification mechanisms (localized surface plasmon mode and optical standing waves or refraction) are used to promote the EM magnification. Such paper card is also exploited successfully as an integrated platform, allowing for ultra-sensitivity (1 × 10−19M) CV and (1 × 10−20M) R6G detection.