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We present a translation of the 1933 paper by R. F\"urth in which a profound analogy between quantum fluctuations and Brownian motion is pointed out. This paper opened in some sense the way to the stochastic methods of quantization developed almost 30 years later by Edward Nelson and others., Comment: 23 pages, 4 figures

While past studies have been carried out to form eco-friendly disposable tableware using non-wood biomass, there is no present groundwork so far where fruit peels waste composited with Mauritian hemp (Furcraea foetida) has been used for such purpose, which is novel to this research work. This study therefore assesses whether the production of 100% biodegradable disposable paper cups with acceptable strength properties using pineapple (Ananas comosus) peels, orange (Citrus sinensis) peels and Mauritian hemp as feedstock is feasible. Soda pulping followed by vacuum molding was done to produce hemp:pineapple peels and hemp:orange peels composite paper cups in different ratios. The cups were tested using relevant standards in terms of appearance and structure, burst strength, tensile strength, weight load, water leakage and biodegradability to find the optimum cup composition by comparing with a suitable control. All cups were visually conformant in terms of color and base stability. The 40:60 hemp–pineapple peels composite cup had characteristics closest to the control, with no cracks and variation rate of weight load, average thickness of 1.42 mm and burst and tensile indexes of 0.25 kPa m2/g and 3.30 Nm/g, respectively. Beeswax coating thickness of 0.70 mm on the optimum cup was adequate to retain cold water for 30 min (minimum) without any leakage. The cup also biodegraded completely in both active soil and damp sand environments within 5 and 6 weeks, respectively. Results therefore reveal that fiber extraction from fruit peel wastes and hemp leaves to produce eco-friendly, biodegradable disposable paper cups is viable.

Although Al-ion battery is attracting researchers’ attention worldwide, its volumetric energy density was not so promising due to low density of graphite-based positive electrodes in the current published literatures. Thus, defect-free yet densely packed graphene electrodes with high electronic conductivity and fast ionic diffusion are crucial to the realization of compacted Al-ion batteries with high volumetric energy density. In the present work, a self-supported and defect-free graphene-positive electrode (RHG-P-2850) was successfully produced by a hydriodic acid reduction of the graphene oxide (GO) method, followed by an ultrahigh temperature (2850 °C) annealing treatment. The density of the RHG-P-2850 (0.32 g cm−3) is currently the highest positive electrode material in the preparation of graphene-positive electrodes from GO. RHG-P-2850 positive electrode enables to deliver considerably high specific capacity 27.1 mAh cm−3 (85 mAh g−1) at the current density 2 A g−1. More importantly, a remarkably stable performance was achieved with 20% fading over 8000 cycles. The results enlighten and promote the design and preparation of densely packed graphene-positive electrode to develop high-performance Al/graphene battery.

Currently the pulp and paper industry is one of the fastest growing sectors of the economy in Russia and other countries. An important aspect of the further development of this industry is associated with an increase in the efficiency of paper production and the quality of finished products with an economical and rational use of raw materials, fuel and energy and other material resources. This is facilitated by the use of modern means of automation and process control. It was experimentally established that there is an extreme dependence between the ratio of the speeds of the paper pulp and the paper machine and the standard deviation of the linear density of the paper web, which determines the degree of non-uniformity of the paper gap. The use of a noise-resistant algorithm for extreme control of an inertial object based on the combination of synchronous accumulation and synchronous detection methods with subsequent search for the maximum amplitude of the second harmonic of the filtered signal, aimed at reducing the root-mean-square deviation of the mass of a square meter of paper web, is considered. It is proposed to simultaneously stabilize the mass flow rate of paper pulp and the coordinate of the fall of the paper pulp jet onto the conveyor mesh, which made it possible to increase the efficiency of paper production.

Photothermal water evaporation using natural solar energy has been attracted more attentions due to wide applications such as water purification, sterilization, power generation and energy conservation. This article reports a low-cost and stable material for efficient generation of water vapor as well as saline and pollution water treatment. The hierarchically porous material consisting of nanoporous carbon and microporous paper is prepared by simply depositing and chemically cross-linking colloidal ink onto a filter paper. A stably homogeneous nanocarbon deposition is formed over microfibers in the paper. The nanocarbon particles greatly increase the surface area of pristine paper (from negligible to 12 m2 g−1) and light absorption. The carbon modified paper allows high water evaporation rate of 1.34 kg h−1 m−2 from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal convective loss to bulk water due to 1D low contact area with water. The pore sizes of filter papers on the water evaporation together with the controlling of surface temperature and evaporating rate are also performed. Finally, this water solar evaporation system is applied for desalination and wastewater purifying (including heavy metal ion and organic pollutions). A safe freshwater is obtained after treatment. This study demonstrates the potential application of chemical modification of inked filter paper to achieve high evaporation rate and efficiency by rational design. A low-cost and stable material for efficient generation of water vapor and wastewater treatment was brought out, which is prepared by simply depositing and cross-linking colloidal ink onto a filter paper. The carbon modified paper allows efficient light absorption, high water evaporation rate from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal energy loss.

We present the study of the preparation of pulp and nanocellulose from Miscanthus × giganteus to improve the quality of the paper for bags. The organosolv miscanthus pulp (OMP) was prepared by the environmentally friendly organosolv method—cooking in a solution of peracetic acid at the first stage and the alkaline treatment at the second stage. Nanocellulose was obtained by hydrolysis of never-dried OMP and subsequent ultrasonic treatment. Structural changes and crystallinity index of OMP and nanocellulose were studied by SEM and FTIR methods. X-ray diffraction analysis confirmed an increase in the crystallinity of OMP and nanocellulose as a result of thermochemical treatment. The nanocellulose had a density of up to 1.6 g/cm3, transparency up to 82%, a crystallinity index of 76.5%, and tensile strength up to 195 MPa. The AFM showed that the particles of nanocellulose have a diameter in the range from 10 to 20 nm. A TGA analysis confirmed that nanocellulose films have a denser structure and lower mass loss in the temperature range 320–440 °C compared to OMP. We established the positive effect of nanocellulose application on the physical and mechanical properties of paper for bags. The application of nanocellulose allows replacing synthetic reinforcing materials and more expensive sulfate unbleached pulp with waste paper in the production of paper and cardboard.

A wide range of applications are possible with paper-based analytical devices, which are low priced, easy to fabricate and operate, and require no specialized equipment. Paper-based microfluidics offers the design of miniaturized POC devices to be applied in the health, environment, food, and energy sector employing the ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment free and Deliverable to end users) principle of WHO. Therefore, this field is growing very rapidly and ample research is being done. This review focuses on fabrication and detection techniques reported to date. Additionally, this review emphasises on the application of this technology in the area of medical diagnosis, energy generation, environmental monitoring, and food quality control. This review also presents the theoretical analysis of fluid flow in porous media for the efficient handling and control of fluids. The limitations of PAD have also been discussed with an emphasis to concern on the transformation of such devices from laboratory to the consumer.

In this work, a novel holey graphene oxide bonded with sulfonic acid groups (S-HGO) was developed using a facile and eco-friendly strategy: erosion and oxidation of graphene oxide (GO) by H2O2 and sulfonation by 4-benzenediazoniumsulfonate. The freestanding paper fabricated by S-HGO shows a high proton conductivity of 4.97 × 10−2 S cm−1 at 60 °C and 100% relative humidity (RH), which is comparable to Nafion 115 (7.67 × 10−2 S cm−1) at the same condition. The holes on S-HGO provide shortcut channels for proton transfer across the GO nanosheet. The chemical-linked sulfonic acid groups afford additional hop sites for proton conduction and endow itself an enhanced thermostability. Under 100% RH and ambient pressure, the freestanding S-HGO deliver a peak power density of 103 mW cm−2 at a load current density of 273 mA cm−2, which is about three times more than that of GO at 35 °C. The results demonstrate that this S-HGO paper is a promising nanoscale inorganic material for proton exchange membranes.

The C/N ratio and organic loading rates (OLRs) are the main constraint factors of anaerobic digestion (AD) which symbols in digestion mortifications due to the rapid accumulation of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN). In this study, the addition of high C-content wastes; paper waste (PW), cardboard waste (CW), and tissue waste (TW) into food waste (FW) feedstock is individually taken into consideration. At first, batch anaerobic digestion is conducted at a balanced C/N ratio of waste materials and then CSTR anaerobic digestion is carried out at different OLRs to investigate the potential of biogas production and process stability, under mesophilic conditions. In batch anaerobic digestion, co-substrate (PW + FW) feedstock is outperformed the other co-substrate feedstocks in terms of biogas production and process stability due to slow formation of VFAs and stable microbial conversion of VFAs into biogas fuel. The highest specific biogas yield (SBY) of 651 mL/gVS and specific methane yield (SMY) of 350 mL/gVS with a 57% rate of biodegradability are obtained from (PW + FW) feedstock at OLR of 15 gVS/L d. Furthermore, (PW + FW) feedstock with superb performance is then subjected to investigate the optimum OLR in CSTR digester for 30 days. The SBY of 22 L/gVS and SMY of 13 L/gVS is obtained with the utmost rate of VS reduction of 96%. The pH, alkalinity, COD, TS reduction, VS reduction, VFAs, and TAN concentration are all in the optimal range at the C/N ratio of 25 and OLR of 2 gVS/L d. This study provides new information regarding the C/N ratio and OLR for AD own great potential in improving the methane yield and productivity of PW and FW.

In this work, the commercial carbon paper was firstly peeled in K2CO3 solution and then was further treated in a KNO3 solution to form functional exfoliation graphene (FEG) on the commercial carbon paper. The FEG/carbon paper was characterized by Raman spectra and scanning electron microscopy, confirming that some typical layered fold graphenes were successfully peeled off and stood on the carbon paper matrix. Then, Fe3O4 nanoparticles (NPs) were grown on the surface of FEG/carbon paper and the as-prepared Fe3O4 NPs/FEG/carbon paper was directly used as supercapacitor electrode. The specific capacitance of Fe3O4 NPs/FEG/carbon paper was about 316.07 F g−1 at a current density of 1 A g−1. Furthermore, the FEG/carbon papers were also functionalized by benzene carboxylic acid to form FFEG/carbon papers, and then the Fe3O4 NPs were grown on the surface of FFEG/carbon paper. The specific capacitance of Fe3O4 NPs/FFEG/carbon paper was 470 F g−1 at a current density of 1 A g−1, superior to some previous reported results. This work might provide a new strategy to prepare various nanostructures on FFEG/carbon papers for future applications.

Calibration curve plays an important role in filter paper method because it affects accuracy in soil suction values. Osmotic coefficient and relative humidity govern the osmotic suction required to develop calibration curve and equation. Most of the researchers used the readily available total (osmotic) suction values from various studies to develop the calibration curve. Very few researchers used the osmotic coefficient in calibration and studied its effect on calibration and measuring suction. In this paper, the effect of the osmotic suction proposed by various researchers on calibration of Whatman 42 Filter paper was studied. Logarithmic and exponential calibration equations were developed and compared. The NaCl solution used in the present study provides limited total suction range of 0–30,000 kPa. The total suction of clayey soil was measured to validate the calibration curves proposed in this study. The feasibility of proposed osmotic coefficients is verified by measuring total suction of soil. The total suction estimated from calibration curve using osmotic coefficients was found to be more accurate.

In this paper, using a low-cost paper fiber (PF) as a substrate, eigenstate polyaniline–coated PFs with graphene (GO/PANI/PF) ternary materials were synthesized by using the chemical oxidative polymerization method. Electrochemical measurements showed that the GO/PANI/PF electrode exhibited an excellent electrochemical performance compared with the PANI electrode. By adjusting the ratio of PANI and PF, the as-prepared GO/PANI/PF–2.5% electrode exhibited the highest specific capacitance 937 F g−1 at current density 1 A g−1 in a 0.5 M H2SO4 aqueous solution, and 74.5% retention of initial capacitance after 2000 charge–discharge cycles at 5 A g−1. The symmetric capacitor on the basis of GO/PANI/PF nanocomposite delivers a superior energy density of 10.12 Wh kg−1 at 456 W kg−1 at a current density of 1 A g−1.

The colour of water-jet rewritable paper (WJRP) is difficult to be expanded via single hydrochromic molecule, especially black. Here, inspired by the amazing phenomenon of bound-water in cells enabling various biological transformations via facilitating synergistic inter-/intra-molecular proton transfer, we present a simple strategy toward WJRP based on binary systems containing less-sensitive acidochromic dyes and mild proton donors (or developers). With such a binary system containing commercial black dye as the colouring agent, benzyl 4-hydroxybenzoate as the developer, and biomimetic bound-water as proton-transferring medium, we successfully achieve the long-awaited black WJRP. Printed images on such WJRP have excellent performances and long retaining time (>1 month). In addition, the robustness, durability and reversibility of WJRP could be increased distinctly by using polyethylene terephthalate as substrate. This strategy significantly expands hydrochromic colours to entire visible range in an eco-friendly way, which opens an avenue of smart materials for practical needs and industrialization., Water based inks used for water-jet rewritable paper (WJRP) are an environmental friendly alternative to conventional printing, but black colour in WJRP could not be realized so far. Here the authors demonstrate black as well as other colour WJRP based on binary systems containing less-sensitive acidochromic dyes and mild proton donors.

There is a need for large-scale, longitudinal studies to determine the mechanisms by which the gut microbiome and its interactions with the host affect human health and disease. Current methods for profiling the microbiome typically utilize next-generation sequencing applications that are expensive, slow, and complex. Here, we present a synthetic biology platform for affordable, on-demand, and simple analysis of microbiome samples using RNA toehold switch sensors in paper-based, cell-free reactions. We demonstrate species-specific detection of mRNAs from 10 different bacteria that affect human health and four clinically relevant host biomarkers. We develop a method to quantify mRNA using our toehold sensors and validate our platform on clinical stool samples by comparison to RT-qPCR. We further highlight the potential clinical utility of the platform by showing that it can be used to rapidly and inexpensively detect toxin mRNA in the diagnosis of Clostridium difficile infections., National Institutes of Health (U.S.) (Grant T32-DK007191)

The non-woven mat has a three-dimensionally distributed fiber structure, but because the randomly dispersed structure caused the pore diameter of the separator to enlarge, this may lead to a short circuit of the battery. In this work, organic polyethylene terephthalate (PET) was combined with inorganic zirconia (ZrO2) ceramic fiber using a low-cost papermaking method. The addition of PET blocked part of the macropores of the fiber separator, enabling the separator a suitable pore size. The PET connected the nodes of the zirconia fibers to provide mechanical support. At the same time, the ZrO2-PET composite separator inherited the excellent high temperature resistance of zirconia ceramic fiber and a maintained dimensional stability after heating at 300 °C for 1 h, providing a strong guarantee for the safe performance of the battery. We found that when the concentration of PET was 5%, the highest electrolyte uptake (301.83%) occurred as well as electrochemical performance. In addition, the ZrO2-PET composite separator achieved an excellent cycle performance at 60 °C compared with the polypropylene (PP) separator.

A Li–O2 battery has been considered as one of the most promising energy storage systems owing to their ultrahigh theoretical energy densities. However, low energy efficiency (high polarization) during discharge/charge and resulting cycle stabilities have severely limited the development of this type of battery. Here, we demonstrate a simple preparation of NiO supported on carbon paper by dipping carbon paper in Ni acetate solution and heating it to apply NiO directly to the carbon as a cathode material for nonaqueous Li–O2 batteries. The prepared sample was confirmed as the structure of NiO-incorporated carbon using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and high-resolution transmission electron microscopy (HR-TEM) analysis despite amorphous patterns seen in XRD (~ 10% NiO in NiO supported on carbon paper). A Li–O2 cell in which the NiO supported on carbon paper was applied as an electrocatalyst showing an initial ~ 6% increase in energy efficiency and a subsequent 50 cycle retention.

This article recalls three papers published by Fred Hoyle and Jayant V. Narlikar consecutively in 1966 in Proceedings of the Royal Society, London. These papers were largely overlooked at the time but a look back today more than fifty years later shows how relevant they might be even today. Fred Hoyle, one of the most imaginative astrophysicists of the twentieth century, gives examples of how his mind functioned running far ahead of the conventional views of the time.

This paper presents a brief overview of the use of magnetic field in studying droplet adhesion to a fiber or a fibrous surface. The paper starts by discussing ways to quantify the force required to detach a droplet from a fiber for its applications in coalescence filtration, i.e., removal of dispersed droplets from a gaseous or liquid flow using a fibrous filter. It then continues to discuss droplet detachment from a fibrous surface or penetrating into a thin fibrous coating. The emphasis is put on a recently develop magnetic approach for measuring force of detachment and on its novel simplicity and non-intrusive nature in the context of existing droplet detachment methods. Our review also includes a discussion on force of detachment for multiphase droplets comprised of two immiscible liquids, i.e., compound droplets. Atomistic- and continuum-level numerical simulations pertaining to droplet detachment are also discussed throughout the paper when appropriate.

The early diagnosis of active hepatitis C virus (HCV) infection remains a significant barrier to the treatment of the disease and to preventing the associated significant morbidity and mortality seen, worldwide. Current testing is delayed due to the high cost, long turnaround times and high expertise needed in centralised diagnostic laboratories. Here we demonstrate a user-friendly, low-cost pan-genotypic assay, based upon reverse transcriptase loop mediated isothermal amplification (RT-LAMP). We developed a prototype device for point-of-care use, comprising a LAMP amplification chamber and lateral flow nucleic acid detection strips, giving a visually-read, user-friendly result in, Current HCV nucleic acid-based diagnosis is largely performed in centralised laboratories. Here, the authors present a pan-genotypic RNA assay, based on reverse transcriptase loop mediated isothermal amplification and develop a low-cost prototype paper-based lateral flow device for point-of-care use, providing a visually read result within 40 min.

Rewritable paper has recently become prevalent in both academic research and marketplace due to the potential environmental advantages, including forest conservation, pollution reduction, energy saving and resource sustainability. However, its real-life applications are limited by a lack of effective strategy to realize multicolour and water-jet printing on rewritable paper with long legible image-lasting times. Herein, we report an effective strategy to construct rewritable paper based on colour or luminescence switching induced by dynamic metal–ligand coordination. This type of rewritable paper can be conveniently utilized for multicolour water-jet printing by using aqueous solutions containing different metal salts as ink. In addition, the printed images on the water-jet rewritable paper can be retained for a long time (> 6 months), which shows great progress compared to previous work. We believe that this type of rewritable paper could be considered as a prototype for multicolour water-jet printing to meet the practical needs., Rewritable paper is environmentally favourable, but its practical realization is stifled by limited ink colour versatility and poor image retention times. Here, the authors exploit the relatively stable but reversible nature of metal–organic coordination bonds to produce long-lasting and multicoloured inks for rewritable paper.

The platinum nanoparticles were grown directly by electrodeposition process on electrochemically oxidized carbon paper (CP) and non-oxidized CP as the anode gas diffusion electrodes (GDEs) for the application in ABPBI-based high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC). XRD, SEM, and CO stripping in the range of 40 to 120 °C were used to investigate the prepared GDEs. Results show that cathodic oxidation of CP has an effect on the CO tolerance of the anode GDE. This enhancement appears to originate from the functional oxygen groups on oxidized CP. Fuel cell results, operating with pure hydrogen at 140 °C, show 230 mW/cm2 and 160 mW/cm2 maximum power densities for cathodic oxidized and non-oxidized GDEs, respectively. It was also found that poisoning by 3% CO for cathodic oxidized electrode at 140 °C display an enhancement in the performance compared with non-oxidized electrode, so cathodic oxidized GDE could be an interesting anode for HT-PEMFCs.

The construction and present condition of Picasso’s Bottle of Vieux Marc, Glass, Guitar and Newspaper 1913, in the Tate collection since 1961, are described. Technical examination, materials analysis and microfading have been carried out on both the support and the collage elements, which include handmade paper, two elements made from broderie anglaise pattern pieces ironed onto paper, damaged water-resistant flock wallpaper and old newsprint. These indicate that the collage is not poorly constructed, but is sensitive to light as was expected, especially the support, pattern pieces and wallpaper. Based on the microfading, the current display recommendation for light exposure is 12 months in 4 years, which is half the exposure recommended for typical works on paper at Tate, at 50–80 lx without ultraviolet light.

Determination of the pH value of the paper is a very specific phenomenon, especially the surface pH measurement. In the case of heritage objects, such as archival documents, books, artworks on paper carriers, is a determination of real pH value in the whole structure (in cross section) of paper very important, because of the mechanism of degradation and thus the rate of degradation of the paper components at a given point in the paper structure depends on the pH value in the environment. This paper is aimed to show the possibilities of using modified papers by acid–base indicator, in the field of measurement of pH value of paper in the cross section of the paper. A calibration series of acidic samples neutralizing by magnesium bicarbonate of different concentrations was created. It was found that the indicator changed in the desired area, pH value 6–8, and it was observed gradual color change. The color parameters were measured and the most correlated parameter with pH value was found. The new method enables the observation of pH distribution in a critical cross section of modified paper after deacidification processes.

Preliminary version. The published version contains a number of small modifications.; International audience; The present paper is a companion of two translated articles by Alfred Clebsch, titled "On a general transformation of the hydrodynamical equations" and "On the integration of the hydrodynamical equations". The originals were published in the Journal für die reine and angewandte Mathematik" (1857 and 1859). Here we provide a detailed critical reading of these articles, which analyzes methods, and results of Clebsch. In the first place, we try to elucidate the algebraic calculus used by Clebsch in several parts of the two articles that we believe to be the most significant ones. We also provide some proofs that Clebsch did not find necessary to explain, in particular concerning the variational principles stated in his two articles and the use of the method of Jacobi's Last Multiplier. When possible, we reformulate the original expressions by Clebsch in the language of vector analysis, which should be more familiar to the reader. The connections of the results and methods by Clebsch with his scientific context, in particular with the works of Carl Jacobi, are briefly discussed. We emphasize how the representations of the velocity vector field conceived by Clebsch in his two articles, allow for a variational formulation of hydrodynamics equations in the steady and unsteady case. In particular, we stress that what is nowadays known as the "Clebsch variables", permit to give a canonical Hamiltonian formulation of the equations of fluid mechanics. We also list a number of further developments of the theory initiated by Clebsch, which had an impact on presently active areas of research, within such fields as hydrodynamics and plasma physics.

Ikot et al. (Indian J Phys 93:1171, 2019) showed an analytical solution of the stationary Schrodinger equation for cesium dimers $$Cs_2$$ at the electronic state $$(3^3\Sigma _g^+)$$ with the shifted Tietz–Wei potential. We point out, however, a miscalculation in solving this equation which had led to erroneous conclusions, particularly about the energy eigenvalues, the partition function and all derived thermodynamic properties. By the way, we present the right expression of the rotational–vibrational energy which shows an excellent agreement with the experimental data.

Executable papers take transparency and openness in research communication one step further. In this comment, an early career researcher reports her experience of creating an executable paper as a journey through Open Science.

In many applications, surface properties of materials or components are more important than the entire volume material properties. The hardness, wear and corrosion resistance of material mainly depends on the surface properties. Improved surface properties also increased the life span of components. The friction stir process is a novel solid-state processing technique that is widely used for welding difficult-to-weld materials. In this paper, the applications of the friction stir process in surface modifications and fabrication of aluminum matrix surface composites were discussed. The effects of friction stir process parameters, tool design, reinforcement and reinforcement techniques on the surface properties were also reported.

It is shown that in A. Einstein’s 1915 paper “Explanation of the perihelion motion of Mercury from the general theory of relativity” an error was actually incurred in the integration of the equation $$ \phi =\left[1+\upalpha \left({\upalpha}_1+{\upalpha}_2\right)\right]\underset{\upalpha_1}{\overset{\upalpha_2}{\int }}\frac{dx}{\sqrt{-\left(x-{\upalpha}_1\right)\left(x-{\upalpha}_2\right)\left(1-\upalpha x\right)}} $$ , and in the result instead of $$ \phi \approx \uppi \left[1+\frac{5}{4}\upalpha \left({\upalpha}_1+{\upalpha}_2\right)\right] $$ (if we limit ourselves to first-order terms in the small quantity (α1 + α2)) the value $$ \phi \approx \uppi \left[1+\frac{3}{4}\upalpha \left({\upalpha}_1+{\upalpha}_2\right)\right] $$ was obtained, where α1 and α2 are the inverse values of the maximum and minimum distances of Mercury from the Sun, $$ \upalpha =\frac{2G{m}_0}{c^2} $$ is the gravitational radius, G is the gravitational constant, m0 is the mass of the Sun, c is the velocity of light (i.e., the Chinese mathematician Hua Di was actually right). And, as a result, for the precession of the orbit of Mercury in the gravitational field of a spherical Sun in the general theory of relativity (after 100 years) one obtains not ~43”, as A. Einstein obtained, but ~71.63”. Exactly this latter result is obtained by direct numerical modeling of the precession of the perihelion of Mercury’s orbit in the gravitational field of the Sun within the framework of the general theory of relativity if the fitting coefficient α in the equation of motion of Mercury (not to be confused with α in the above equations) is set equal to zero. The result $$ \phi \approx \uppi \left[1+\frac{3}{4}\upalpha \left({\upalpha}_1+{\upalpha}_2\right)\right] $$ , obtained by A. Einstein if it is obtained, happens only upon integration of either the equation $$ \phi =\left[1+\frac{\upalpha}{2}\left({\upalpha}_1+{\upalpha}_2\right)\right]\underset{\upalpha_1}{\overset{\upalpha_2}{\int }}\frac{dx}{\sqrt{-\left(x-{\upalpha}_1\right)\left(x-{\upalpha}_2\right)\left(1-\upalpha x\right)}} $$ (if we also limit ourselves to first-order terms in the small quantity (α1 + α2)), i.e., in front of the integral in brackets the coefficient 1/2 should stand in front of the quantity α, or the equation $$ \phi =\left[1+\upalpha \left({\upalpha}_1+{\upalpha}_2\right)\right]\underset{\upalpha_1}{\overset{\upalpha_2}{\int }}\frac{dx}{\sqrt{-\left(x-{\upalpha}_1\right)\left(x-{\upalpha}_2\right)\left(1-\upalpha x\right)}} $$ (if we also limit ourselves to first-order terms in the small quantity (α1 + α2)), i.e., in the denominator under the differential in the integral, inside the square root\ a plus sign should stand in front of the quantity αx.

Free-standing paper-like electrochemical sensors have many advantages such as high flexibility, thickness adjustability, and large electroactive surface area, when compared to traditional metal electrodes. Generally, carbon nanomaterials, e.g., graphene and carbon nanotubes (CNTs), are main materials of paper-like sensors, and these materials are supported by different species such as metal nanoparticles, dyes, and polymers. We present the fabrication procedure of free-standing composite paper electrode including CNTs and methylene blue (MB) with a simple vacuum filtration process of a suspension including oxidized CNTs (CNTs-ox) and MB through a suitable membrane. CNTs-ox/MB paper was peeled from membrane, and this paper was electrochemically reduced to improve its electrical conductivity. Characterization of this paper-like electrode was performed by using scanning electron microscopy, scanning tunneling microscopy, electron-dispersive X-ray analysis, powder X-ray diffraction spectroscopy, Raman spectroscopy, UV-vis absorption spectroscopy, four-point probe electrical conductivity, and cyclic voltammetry techniques. Amperometric response of the composite paper electrode for determination of nitrite was linearly proportional to nitrite amount in the range of 12–2500 μM, with a detection limit of 3.6 μM. The sensitivity of the free-standing CNTs/MB paper sensor was calculated as 0.40 μA μM−1 cm−2.

In this paper, the surface hydrophilicity of carbon paper was modified by use of Caro’s acid, and MnO2 electrodeposited on carbon paper (CP) or surface-modified carbon paper (SMCP) were prepared through an anodic electrochemical deposition method. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of CP, SMCP-30, SMCP-60, and SMCP-90 indicated that the peaks at 1054, 1214, 1722, and 3426 cm−1 correspond to the stretching vibrations of C–O, C–H, C=O, and –OH. Our study results show that with the extension period of oxidation treatment time, the corresponding content of these groups C–O, C–H, C=O, and –OH increased; then, their surface hydrophilic properties enhanced; and finally, their capacitances increased. This study results indicate that introducing these groups C–O, C–H, C=O, and –OH into the surface of electrode materials is an important strategy for improving their capacitances.

Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials., The rapid evolution of consumer electronics means that out-of-date devices quickly end up in the scrap heap. Here, the authors fabricate electrical components using biodegradable and flexible cellulose nanofibril paper—a natural sustainable resource derived from wood.

In this work, Pd and PdNi nanostructured particles have been deposited on the carbon paper (CP) by a novel and simple method of in situ deposition. The prepared catalysts were named as Pd-situ/CP, PdNi-situ/CP. The as-formed Pd and Pd-Ni nanoparticles are well dispersed with the sizes of 15∼24 nm for Pd-situ/CP, 8∼11 nm for Pd9Ni1-situ/CP, and 8∼14 nm for Pd8Ni2-situ/CP. Their electroactivity for ethanol oxidation in 1 mol L−1 NaOH solution was investigated with cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The samples fabricated by this in situ deposition method (Pd-situ/CP, Pd9Ni1-situ/CP, and Pd8Ni2-situ/CP) exhibit both higher electroactivity and higher electrocatalytic stability for ethanol oxidation than the Pd/CP obtained by the conventional NaBH4 reduction method. This new method of preparation of catalyst nanoparticles is simple and hardly leads to the loss of catalyst particles due to the omitted filtration step of catalyst particles.

Exploiting the advantages of additive patterning process over complex fabrication processes, herein we report the fabrication of field-effect transistor (FET) using the screen-printing method. The graphene conductive composite dielectric ink as the channel and the dielectric layer respectively was screen printed on cellulose paper substrate. The fabricated device shows the hole and electron mobility of 135 $$\hbox {cm}^{2}/$$ V s and 98 $$\hbox {cm}^{2}/$$ V s respectively with an ultra-low leakage current of $$\sim $$ 25 nA. The proposed technique can be used for large-scale roll-to-roll commercial manufacturing of disposable FET-based sensors such as temperature and IR sensors, health monitoring devices etc.

In this note, we make two revisions of the paper [2]. The first one is the asymptotic behavior of the energy functional as $$t\rightarrow T$$ (see [2, Theorem 1.6]), where T is the blow-up time. The second one is the equivalent conditions for the solutions blowing up in finite time or existing globally (see [2, Theorem 1.8]).

This work deals about the development of paper-based fuel cells with high open-circuit voltages for application in powering the micro-nanosystems such as bio-sensors. The developed fuel cell employs Whatman paper as the ion conductor placed between the anode and the cathode to replace expensive ion-conducting membranes such as Nafion. A maximum open-circuit voltage of ∼2.1 V per single cell and a power output of ∼4.5 mW cm−2 at ∼6 mA cm−2 are obtained when employing 1 M NaBH4 in 20 wt% NaOH solution and 1 M VO2 + in 2.5 M H2SO4 solution. Chronoamperometric measurement performed at 1 V indicates that the output power density varies from 6 to 1 mW cm−2 in about 100 min. The power delivered at the end of even 100 min is comparable to that of the peak power delivered by many of the micro-fuel cell systems reported in the literature.

In this paper, a structure with growing MnO2 nanowires (NWs) on activated carbon paper was designed and prepared using a simple hydrothermal method. Electrochemical measurements show that the specific capacitance of these MnO2 nanowires/ACP reached 390 F g−1 at a scan rate of 10 mV s−1 and 529 F g−1 at a current density of 2.0 A g−1. The long-term cycle life stability for MnO2 nanowires/ACP was examined and the results show that the capacitance decay was ~12% over 5000 cycles, indicating its long cycle life. Furthermore, they could also be used to assemble simple solid-state supercapacitors with high capacitance. These results show that the MnO2 nanowires/ACP could be a promising electrode material for energy storage.

In this report, the supercapacitor was constructed with activated carbon paper as electrodes and 3 M H2SO4 solution bearing 1 M VOSO4 as electrolyte. This supercapacitor showed high areal capacitance of 2146 mF/cm2 with around 16 times higher than that of 134 mF/cm2 in pristine electrolyte of 3 M H2SO4 and good cycling performance retaining 92 % after 5000 cycles. The full-scale and enlarged Nyquist-type impedance spectra further indicate that the supercapacitor has low diffusion resistance and exhibits good power capability. Constructed by this way, the performances of supercapacitors were improved for the synergistic effect of the absorbance and catalysis of the activated carbon paper as well as redox properties of the couples VO2+/VO2 +.

Graphene-carbon nanofiber/MnO2 nanocomposite paper (GMP) is prepared via a simple chemical reaction between KMnO4 and carbon materials in acidic solution, in which MnO2 nanosheets are uniformly deposited on the graphene-carbon nanofiber paper. Owing to its freestanding structure, GMP is directly used as an electrode in the electrochemical tests without addition of any binders or conductive additives. Encouragingly, GMP exhibits an excellent capacitive performance with a high specific capacitance of 298.2 F g−1 at 1 A g−1 in 1 M Na2SO4 electrolyte. Meanwhile, this composite paper can withstand high scan rate loads without a large decrease of capacitance, the specific capacitance can be remaining at 370.4 F g−1 even at 300 mV s−1. In the cycling test, the composite paper presents an outstanding stability with 95.7 % capacitance retention after 3000 cycles. Additionally, the asymmetric supercapacitor is fabricated based on GMP electrode, it not only shows a high operating voltage of 2.0 V but also exhibits a high energy density of 23.0 Wh kg−1 at 450.8 W kg−1. Therefore, this kind of composite paper would be promising as electrode materials for flexible and high performance supercapacitors.

The aim of this paper is to discuss the main result in the paper by D.Y. Gao and X. Lu [On the extrema of a nonconvex functional with double-well potential in 1D, Z. Angew. Math. Phys. (2016) 67:62]. More precisely we provide a detailed study of the problem considered in that paper, pointing out the importance of the norm on the space $C^{1}[a,b]$; because no norm (topology) is mentioned on $C^{1}[a,b]$ we look at it as being a subspace of $W^{1,p}(a,b)$ for $p\in [1,\infty]$ endowed with its usual norm. We show that the objective function has not local extrema with the mentioned constraints for $p\in [1,4)$, and has (up to an additive constant) only a local maximizer for $p=\infty$, unlike the conclusion of the main result of the discussed paper where it is mentioned that there are (up to additive constants) two local minimizers and a local maximizer. We also show that the same conclusions are valid for the similar problem treated in the preprint by X. Lu and D.Y. Gao [On the extrema of a nonconvex functional with double-well potential in higher dimensions, arXiv:1607.03995]., 12 pages; in this version we added the forgotten condition $F(x) \ne 0$ for $x\in (a,b)$ on page 3

In this report, the activated carbon papers were prepared by the modified Hummer’s method. After the treatment by the modified Hummer’s method, the specific surface areas of carbon papers enlarged and the surfaces became wettability. Further, the electrochemical behaviors for the activated carbon papers were measured. They exhibit higher electrochemical activities for VO2+/VO2 + redox reaction than the unactivated counterparts upon application as vanadium redox battery, which is ascribed to the synergistic effect of surface wettability and catalysis of the docked –OH and –COOH groups.

We demonstrate the working of a solvent treated paper resistor for resistor, capacitor filter circuit operation and relative humidity sensing. The paper resistor has been fabricated by solvent treatment method, where a piece of photocopier paper is treated with sodium chloride solvent and upon deposition of sodium chloride micro crystals at the micro pores of the paper, it is marked with graphite pencil linings for external circuit connection. Also, dependence of paper resistance on moisture level content in surrounding environment has been investigated. We envision potential applications of our designed paper resistor as an inexpensive alternative to electrical resistance and relative humidity sensor.

We present an annotation of Hans Bethe’s “Bremsformel fur Elektronen relativistischer Geschwindigkeit” [Zeitschrift fur Physik 76, 293 (1932)] (Braking Formula for Electrons of Relativistic Speed). The English translation of the paper appears as a companion to this annotation. We highlight the conceptual and historical aspects of the relevant quantum electrodynamics employed by Bethe, provide details in the derivation of several equations, and point out some typographical errors in the original manuscript.