Search

This document is a summary of a special issue of the journal Catalysts, which focuses on recent advances in the field of photocatalysis. The issue includes seven exclusive papers written by members of the editorial board and topical advisory panel. The papers cover a range of topics, including the use of gadolinium-doped bismuth ferrite for the photocatalytic oxidation of arsenite, the effect of heterovalent doping on the photoelectrochemical behavior of anatase TiO2, the synthesis of novel ternary composites for photocatalytic degradation, the preparation of metallic MoS2/WS2 dual co-catalysts for hydrogen production, the development of a photocatalyst for removing bisphenol A from water, the synthesis of Au/TiO2/WO3 heterostructures for photodegradation and dye sensing, and the design of furane-based photoinitiators for polymerization. The authors conclude that there is still much research to be done in the field of photocatalysis, particularly in terms of the type of light irradiation, substrate immobilization, and the search for new photocatalysts. [Extracted from the article]

1 Amorphous carbon was facilely obtained via the treatment of waste papers with sulfuric acid. 2 The combination of amorphous carbon with graphitic carbon nitride leads to an increased photo-catalytic H 2 generation. 3 The enhancement in H 2 generation is resultant from the efficient separation of electrons and holes owing to the excellent electrical conductivity of amorphous carbon. Up-cycling of waste papers to value-added carbon products has significant environmental and economic benefits in real life. This work aims to recycle the waste papers to construct amorphous carbon modified graphitic carbon nitride composite photocatalysts for efficient photocatalytic hydrogen generation from water under visible light. Amorphous carbon (labeled as a-C) was yielded from the office waste papers by simple sulphuric-acid treatment and then combined with graphitic carbon nitride (g-CN) to form the g-CN/a-C composite photocatalysts by the thermolysis of a-C and melamine mixture. The addition of a-C enlarges the surface area of g-CN from 11.52 m2 g−1 of pristine g-CN to 28.12 m2 g−1 of g-CN/a-C-100. In addition, the a-C incorporation can significantly separate the electrons from the photoexcited g-CN owing to the excellent conductivity of a-C. As a result, an increased photocatalytic H 2 generation was realized under visible light exposure. The g-CN/a-C-100 sample with optimized a-C contents offers the highest photocatalytic H 2 generation rate of up to 17.1 μ mol h−1, which is ∼12 times higher than that of pristine g-CN under the same condition. The present study manifests the great potential of the recycling of office waste papers for increased photocatalytic H 2 generation. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

The use of microfluidic fuel cells (μFCs) as power sources in the development of non-implantable biomedical devices, such as patch sensors, could be broadened with the use of physiological fluids as fuels and the use of low-cost materials. In this work, we report the evaluation of a paper-based photo-μFC working with human blood as fuel, and we implement a nanocomposite as anode that presents photoactivity under visible light. The electrocatalyst was synthesized using Zn(NO3)2 and TiCl4 as precursors of the ZnO and the TiO2, respectively, which were coated with Au nanoparticles. It was demonstrated that ZnO and TiO2 nanoparticles consisted of crystals with wurtzite and anatase phases, with average sizes of 26.6 and 19.5 nm, respectively, and the TiO2/ZnO/Au nanocomposite presents 2.62 eV of band gap energy, demonstrating its photoactivity under visible light irradiation. The photocatalyst was tested as photoanode in half-cell for glucose oxidation in aqueous solutions, under illumination and dark conditions, showing characteristics peaks of glucose oxidation in both cases, but higher current was generated under illumination. Finally, we present the implementation of this anode and the construction of a paper-based photo-μFC using human blood as fuel; its performance was evaluated under visible light irradiations and in the dark. The results show a better performance under illumination with voltage, current, and power density values of 0.95 V, 1.2 mA cm−2, and 0.458 mW/cm2, respectively, compared to the corresponding values of 0.8 V, 0.96 mA cm−2, and 0.274 mW/cm2 in dark conditions. [ABSTRACT FROM AUTHOR]

Paper-based artifacts, such as ink and wash paintings, paper cuts, etc., when exposed in environment for a long time, are prone to embrittling, yellowing and ageing because of ultraviolet light and weather elements. In a museum, special measurements are adopted to avoid these damages, but for common households, a functional coating is a good solution. However, this is not an easy task as the coating must be removable and cannot damage the articles. Graphene oxide (GO) has the potential as ultraviolet shielding material for the protection of paper-based artifacts, but the application of monolithic GO coatings on paper-based artifacts is difficult. In this work, feasible GO/polyacrylonitrile composite films were prepared and their protection properties for rice paper were explored experimentally. When GO loading reached 2 %, the UV-A and UV-B blocking percentages of the film were 57.47 % and 70.86 %, respectively, with a visible light transmittance of 77.09 %. These films also performed good moisture resistance. With a good flexibility, they could be easily transferred onto and peeled off the rice paper surface without damaging the paper texture and patterns on it. These films basically meet the demand of paper-based artifacts protection. [ABSTRACT FROM AUTHOR]

"Paper" plays an important role in the development and spread of civilization. However, massive use of paper has led to nonnegligible negative influence on environment. Recently, great progresses have been made in the fields of rewritable paper that has enormous potential in alleviating the increasing demand for paper. Therefore, we report a new photochromic tetraphenylethene-based Schiff base derivative 2-ethoxy-6-(((4-(1,2,2-triphenylvinyl)phenyl)imino)-methyl)phenol (TPENOEt). TPENOEt exhibits reversible photochromic behavior, fast response, simple synthetic step, lower cost and excellent fatigue resistance. The bleaching rate of TPENOEt is tunable by longer wavelength light, white light irradiation and elevated temperature. The fluorescence of TPENOEt is weak in solid state, which increases obviously after grinding with a pestle accompanied by reduced photochromic efficiency and longer response time. These results provide a new view to get insight into the relationship between packing style and fluorescence/photochromism property of Schiff base derivatives. TPENOEt is successfully applied as a visible light driven rewritable paper, 410 nm violet light can serve as a pen, while 420–590 nm visible light and white light is employed as the eraser. The recorded information will be erased in about 15 s after white light irradiation and will be self-erased in 20 min in daylight and in about 15 days in dark. Moreover, TPENOEt can also serve as a UV strength sensor for naked eye detection of UV radiation pollution. Image 1 • TPENOEt exhibits reversible photochromic behavior, fast response, and excellent fatigue resistance. • TPENOEt is successfully applied as a visible light driven rewritable paper. • The recorded information on TPENOEt will be self-erased in 20 min in daylight and in about 15 days in dark. [ABSTRACT FROM AUTHOR]

CuO nanoflakes with dimension of 50–150 nm × 200 nm were successfully immobilized on the surface of cellulose fibers by an ultrafast (5 min reaction time), scalable microwave assisted method. The high retention of CuO up to 70% has been phenomenal considering that the immobilization was carried out in the absence of any linker, binder or retention aid. Retention of almost 87% of the immobilized CuO nanostructures even after five consecutive recyclability steps has been unprecedented. The antimicrobial activities of the paper matrices have been investigated by deactivating both G. trabeum and E. coli. The CuO immobilized paper matrices have desisted the growth of G. trabeum up to 28 days and completely deactivated E. coli (CFU in order of 107) in the presence of visible light with exposure time of 2 h only. [ABSTRACT FROM AUTHOR]

In this work, the effect of using Ag-doped TiO2 nanopigments on optical, mechanical and antimicrobial properties of coated paper was explored. Furthermore, the long-term antimicrobial activity of the coated paper was examined for up to 25 years. Titanium dioxide (TiO2) nanoparticles have been synthesized and doped with different percentages of Ag nanoparticles (Ag NPs) using a simple wet chemical approach. The Ag@TiO2 modified nanopigments were in the form of nanorods with an average size of about 20 nm as observed from TEM images. Increasing Ag content from 0.01 to 1.0% showed an increase in the mechanical properties of coated paper in terms of tensile, stretching, tensile energy absorption and burst while preserving the optical properties. Moreover, the antimicrobial inhibition activity increased with increasing the Ag content. The 1% Ag@TiO2 showed a long-lasting antimicrobial effect against Staphylococcus aureus (S. aureus) Gram-positive bacteria even after 25 years of ageing (93.4% inhibition). Investigation of reactive oxygen species (ROS) generation and reaction mechanism of antimicrobial activity over Ag/TiO2 under visible light is proposed. These results suggest that Ag/TiO2 NPs can be potentially used as a disinfection coating for paper and improving its mechanical properties. [ABSTRACT FROM AUTHOR]

N-doped TiO2 (N-TiO2) photocatalyst was prepared by the sol-gel method, using butyl titanate and urea as raw materials, and then loaded onto diatomite to prepare a composite photocatalyst. Bleached sulfate softwood pulp fiber was dissolved and mixed with the composite photocatalyst and then regenerated to prepare composite fillers for the manufacture of visible light-responsive photocatalytic paper suitable for the removal of toxic formaldehyde gas. Photocatalytic paper containing 20% composite filler with a ratio of 4/6 N-TiO2 (60% N-doping)/diatomite had good photocatalytic activity, with 50.1% formaldehyde degraded after 10 h under visible light irradiation. This photocatalytic paper also had good physical properties, with a paper density of 0.36 g cm−3, a burst index of 3.0 kPa·m2 g−1 and a tensile index of 43.33 Nm g−1, indicating that it has good prospects for removal of indoor air pollutants. [ABSTRACT FROM AUTHOR]

Quantification of the degradation behaviour of heritage objects is essential to manage the rate of degradation and hence optimise their lifetime. In this research, a 23 full factorial experiment was carried out to deepen the understanding of the photodegradation of historical rag paper induced by continuous polychromatic visible radiation. Oxygen concentration, relative humidity and illuminance were investigated as the three environmental factors of primary concern. The effects of these factors on the rate constant of change in diffuse reflectance and tristimulus discolouration were investigated by analysis of variance and multiple linear regression. The three main effects were found to contribute the most to the rate of photodegradation of historical paper, among which relative humidity played the most important role whereas illuminance played the least. This observation is likely to hold when extrapolating the experimental conditions to real conditions in collection storage and display. [ABSTRACT FROM AUTHOR]

In this paper, an indium‐gallium‐zinc oxide (IGZO) based phototransistor with an electrohydrodynamic (EHD) jet printed poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) absorption layer has been developed for the absorption of visible light. The PEDOT:PSS absorption layerforms a p‐n junction with IGZO, enhancing the photoresponse through selective carrier transfer of photogenerated carriers. As a result, the proposed phototransistor exhibits improved optoelectronic characteristics such as photoresponsivity of 8.40 × 102 A/W, photosensitivity of 1.12 × 107, detectivity of 8.05 × 1011 Jones under the green light (532 nm) illumination of 5 mW/mm2. [ABSTRACT FROM AUTHOR]

An ultra-sensitive paper-based molecularly imprinted sensor for detection of H5N1 was described. The results can not only be detected quantitatively by fluorescence, but also can be directly read with naked eyes under visible light or ultraviolet light within 10 min. With naked eye detection, its sensitivity is obviously better than that of commercial kits. In particular, the cost of the sensor is cheap (Original size: RMB 1.53 Yuan each; Smaller size: RMB 0.08 Yuan each), which is beneficial to application. [Display omitted] • Paper-based molecularly imprinted sensor; • Ultra-sensitive detection of H5N1 (LOD, 0.58 fM); • Rapid visual detection of influenza H5N1 within 10 min; • More intuitive and sensitive results than commercially available kit; • Low cost (Original size, 1.53 yuan/piece; Smaller size, 0.08 yuan/piece). The rapid detection of pathogens is important to the control of epidemics. Here, a paper-based molecularly imprinted sensor has been developed for the visual detection of influenza H5N1 virus. Firstly, the paper-based molecularly imprinted was prepared by a sol–gel reaction. Then, H5N1 ∼ Apt was covalently bound to the surface of the ZIF-8-NH 2 coated with rhodamine B (RhB) through an amide bond, to produce the fluorescent and colorimetric probe ZIF-8-NH 2 @RhB ∼ Apt. When H5N1 and ZIF-8-NH 2 @RhB ∼ Apt are added to the paper-based MIPs, the H5N1 will be combined with MIPs through the synergistic effects of shape and size compatibility and interaction with the functional groups of the monomers, and ZIF-8-NH 2 @RhB ∼ Apt will bind to H5N1 through its aptamers to form a sandwich structure. The sensor has ultra-high sensitivity and the detection limit is 0.58 fmol/L by using fluorescence spectroscopy. A semi-quantitative signal can also be observed with the naked eye within 10 min. A comparative study showed that direct visual detection was highly reliable, and the sensitivity was better than that achieved with a commercially available kit. Importantly, the paper-based sensor is low in produce cost (Original size: RMB 1.53 Yuan each; Smaller size: RMB 0.08 Yuan each) and is easy to cut, store and carry. This sensor is expected to allow self-service, visual, high-throughput, and real-time virus detection, which is of great significance for epidemic prevention and control. [ABSTRACT FROM AUTHOR]

Accurate measurement of the moisture content of paper is essential in papermaking and is also important in some paper-based microfluidic devices. Traditional measurement techniques provide very limited spatiotemporal resolution and working range. This article presents a novel method for moisture content measurement whose operating principle is the strong correlation between the optical transparency of paper and its moisture content. Spectrographic and microscopic measurement techniques were employed to characterize the relation of moisture content and relative transparency of four types of paper: hardwood chemi-thermomechanical pulp paper, Northern bleached softwood kraft paper, unbleached softwood kraft paper, and General ElectricR Whatman grade 1 chromatography paper. It was found that for all paper types, the paper transparency increased monotonically with the moisture content (as the ratio of the mass-of-water to the mass-of-dry-paper increased from 0% to 120%). This significant increase in relative transparency occurred due to the refractive index matching role of water in wet paper. It is further shown that mechanical loading of the paper has little impact on the relative transparency, for loadings that would be typical on a paper machine. The results of two transient water absorption experiments are presented that show the utility and accuracy of the technique. [ABSTRACT FROM AUTHOR]

External-stimuli-responsive rewritable paper has attracted significant attention for application in secure information. However, to encrypt information on papers which can not be read out under visible light is still challenging. In this work, recessive rewritable paper for security information handling was realized via sectional intramolecular charge transfer (SICT) manipulating in a delicately designed coumarin derivative CMNT. By rational arranging a thiophenyl group and a diethylamino group as electron donors at the 3- and 7-position of coumarin skeleton, respectively, CMNT exhibited obvious fluorescence switching upon BF 3 and trimethylamine stimuli. After impregnating a filter paper into CMNT solution with low concentration (1 × 10−6 M), no color change of the paper could be observed under visible light. Meanwhile, when writing and erasing the information on the paper by BF 3 ink and trimethylamine eraser, respectively, the process can only be witnessed under UV light. Studies revealed the ICT effect from diethylamino group to chromen-2-one was suppressed after adding BF 3 , while the ICT channel from thiophenyl group to chromen-2-one was retained, thus producing such unique phenomenon. A recessive rewritable paper was developed based on a coumarin derivative with sectional intramolecular charge transfer manipulating. [Display omitted] • A D'-A-D coumarin derivative named CMNT , with simple structure based on the ICT effect was designed and synthesized. • CMNT can be a reversible BF 3 sensor and the sensing system was realized by sectional intramolecular charge transfer. • A recessive rewritable paper was fabricated by impregnating a filter paper into CMNT solution (1×10-6 M). • The writing by BF 3 ink is only readable on exposure to ultraviolet light, and is trimethylamine erasable for rewriting. [ABSTRACT FROM AUTHOR]

Immunoglobulin E (IgE), a biomarker of allergic diseases, plays a critical role in allergic mechanism. Because of its low abundance in serum, the demand of developing sensitive, selective and simple methods for IgE detection is still very urgent. Paper-based analytical devices using upconversion nanoparticles (UCNPs) as the label can be promising point-of-care test (POCT) methods in rapid diagnosis, owing to their NIR-excitation and visible light emission nature, which can avoid the interference of autofluorescence and scattering light from biological samples and paper substrates. In this work, we proposed a paper-based analytical device for the sensitive, selective and accurate detection of total immunoglobulin E (IgE) in human serum. The assay was based on resonance energy transfer between UCNPs and organic dye tetramethylrhodamine (TAMRA), and IgE aptamer with stem-loop structure was used as the recognizing probe. The existence of IgE change the conformation of IgE aptamer, enlarge the distance between donor and acceptor, and block the energy transfer process. Thus, the luminescence of UCNPs recovered with an IgE concentration independent manner. A linear calibration was obtained in the range of 0.5–50 IU/mL, with a detection limit of 0.13 IU/mL. The results of our method were well correlated with that of commercial ELISA kit (20 human serum samples). This work suggests promising prospect of the paper-based UC-LRET analytical devices in real samples and may promote the application of paper-based analytical devices in clinical diagnosis. Based on UC-LRET technique and IgE aptamer with stem-loop structure, a sensitive, selective and accurate paper-based aptasensor was developed for IgE detection in human serum. Image 1 • Novel paper-based UC-LRET aptasensor was developed for sensitive, selective and accurate detection of IgE in human serum. [ABSTRACT FROM AUTHOR]

Paper and silk are the artworks with the highest light sensitivity. They are very vulnerable to photochemical reactions caused by the radiation of light sources in museum lighting, resulting in irreversible permanent damage such as color fading and discoloration. The basis of lighting protection for these artworks is to clarify the influence of different light sources on paper and silk materials. In this study, 10 kinds of narrow band monochrome light in the visible light range were used as experimental light sources, real cultural relics paper and silk materials were used as experimental samples, and long-term irradiation experiments were carried out under constant temperature and humidity conditions. The color parameters of paper and silk irradiated by different light sources were detected periodically, and the curve of color difference with exposure was drawn. The relative influence coefficients of different spectral bands on the color of paper and silk were obtained by curve analysis. By fitting data regularity and regression analysis, the "relative damage-spectral composition" function was established. The effect of light source on color damage of paper and silk is described by mathematical language, and the influence formula of different spectrum on color damage of paper and silk is obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acidification defines the preservation state of Xuan paper in museums. • Photochemical damage to Xuan paper is owing to oxidation and hydrolysis reactions. • FTIR combined with PCA is able to evaluate photochemical damage law of Xuan paper. • pH values, λ, and their interaction promotes photochemical damage to Xuan paper. • Photochemical damage is fitted as a mathematical function of pH values and λ. In museums, there is a huge storage of Xuan paper cultural relics with profound historical and artistic significances. Exploring the photochemical damage behavior of Xuan paper that is generally in acidification, namely its damage mechanisms and laws, is crucial for the preventive lighting protection for paper cultural relics. In this study, the accelerated aging experiments in the range of visible light were conducted on Xuan paper samples with different degrees of acidification. The photochemical damage mechanisms of samples were traced, which is related with the synergistic effects of oxidation and hydrolysis reactions. It can be found that there is an effect of acidification, a long-standing material property of Xuan paper, on its damage, which further defines its preservation state in museums. On this basis, a spectral quantification method of infrared spectra combined with the principal component analysis was proposed to comprehensively analyze the photochemical damage law of Xuan paper in different preservation states. The analysis shows that the effect of acidification degree (pH values), spectra wavelength (λ), and their interaction on the damage to Xuan paper are statistically significant. Furthermore, the fitted mathematical function of pH values and λ is of great importance for evaluating photochemical damage, in order to further develop preventive lighting protection applications. [ABSTRACT FROM AUTHOR]

Liquid crystal (LC) lasers use a layer of chiral nematic liquid crystal to form a self‐organising resonant cavity. When doped with fluorescent dye and suitably excited, they form versatile micro‐lasers with high efficiencies, low thresholds, and selective wavelength emission across a continuous range of the visible spectrum. This, combined with their scalable fabrication, makes them attractive candidates for a wide variety of photonic applications, including laser displays. This paper includes a review of the principles of operation, of recent enhancements that are advancing the technology closer to market, and concludes with demonstrations of LC lasers used for medical imaging and low‐speckle holography. [ABSTRACT FROM AUTHOR]

[Display omitted] The pulp and paper sectors are thriving yet pose significant environmental threats to water bodies, mainly due to the substantial release of pollutants. Lignin-derived compounds are among the most problematic of these contaminants. To address this issue, we present our initial results on utilizing organic semiconductor photocatalysis under visible light for treating lignin-derived compounds. Our investigation has been centered around creating a green and cost-effective organic semiconductor photocatalyst. This catalyst is designed using a structure of bagasse cellulose spheres to support PM6 (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2- b :4,5- b' ]dithiophene))– co -(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2- c :4,5- c' ]dithiophene-4,8-dione))]: MeIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-cyclopentane-1,3-dione[ c ]-1-methyl-thiophe))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3- d:2′ , 3′-d' ]-s-indaceno[1,2- b :5,6- b' ]-dithiophene)). This photocatalyst demonstrates remarkable efficiency, achieving over 91 % degradation of lignin-derived compounds. The superior photocatalytic performance is attributed to three main factors: (1) The ability of PM6 to broaden MeIC's absorption range from 300 to 800 nm, allowing for effective utilization of visible light; (2) the synergistic interaction between PM6 and MeIC, which ensures compatible energy levels and a vast, evenly spread surface area, promoting charge mobility and extensive donor/acceptor interfaces. This synergy significantly enhances the generation and transport of carriers, resulting in a high production of free radicals that accelerate the decomposition of organic materials; (3) The deployment of PM6:MeIC on biomass-based carriers increases the interaction surface with the organic substances. Notably, PM6: MeIC showcases outstanding durability, with its degradation efficiency remaining between 84 % and 91 % across 100 cycles. This study presents a promising approach for designing advanced photocatalysts aimed at degrading common pollutants in papermaking wastewater. [ABSTRACT FROM AUTHOR]

Flexible broadband photodetectors based on 2D MoS2 have gained significant attention due to their superior light absorption and increased light sensitivity. However, pristine MoS2 has absorption only in visible and near IR spectrum. This paper reports a paper-based broadband photodetector having ZnS-MoS2 hybrids as active sensing material fabricated using a simple, cost effective two-step hydrothermal method wherein trilayer MoS2 is grown on cellulose paper followed by the growth of ZnS on MoS2. Optimization in terms of process parameters is done to yield uniform trilayer MoS2 on cellulose paper. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near IR. ZnS plays the dual role for absorption in UV and in the generation of local electric fields, thereby increasing the sensitivity of the sensor. The fabricated photodetector exhibits a higher responsivity toward the visible light when compared to UV and IR light. Detailed studies in terms of energy band diagram are presented to understand the charge transport mechanism. This represents the first demonstration of a paper-based flexible broadband photodetector with excellent photoresponsivity and high bending capability that can be used for wearable electronics, flexible security, and surveillance systems, etc. [ABSTRACT FROM AUTHOR]

In this work, based on transfer printing technology, planar integration of RGB InGaN‐based micro‐LEDs on flexible transparent material was realized. By measuring the optoelectronic parameters, we demonstrated the feasibility of this integrated device in full‐color display applications. In addition, based on the on‐off keying modulation and wavelength division multiplexing, visible light communication in parallel channels can be achieved. Relevant studies have demonstrated the broad prospects of InGaN‐based micro‐LED devices in multifunctional flexible integrated optoelectronics applications. [ABSTRACT FROM AUTHOR]

Abstract: Ink‐free printing based on rewritable paper is an efficient and environmental friendly way to reuse paper, protect resources, and save energy for sustainable development of human society. Among various kinds of rewritable media, light responsive rewritable paper (LRP) is one of the most popular research areas due to its clean and favorable noncontact writing. Visible light is more suitable for LRP for its superior penetration and much less damages to organic molecules than UV light. However, visible‐light‐responsive rewritable paper (VLRP) has only limited successes so far. Herein, a VLRP is newly designed and fabricated based on photoinduced proton transfer (PPT) between photoacid and pH‐sensitive dyes. Success of it is highly benefited from systematical investigation and in‐depth understanding on the key influence factors, such as concentration‐induced undesired isomerization, temperature, humidity, and light intensity, on the PPT and its inverse process. As‐prepared VLRP shows long‐awaited properties, such as, high color contrast and resolution, appropriate legible time of prints, excellent reversibility (>100 cycles), easiness to achieve multicolor prints, and agreeing well with environmental concept of green printing. In addition, study of influence factors on PPT in this work, to some extent, may also help people understand complex photocycle process in biosystem. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the American Institute for Conservation is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The low efficiency of photocatalytic nitrogen fixation to ammonia is determined by the low quantum efficiency photocatalyst and the configuration of the reactor.Therefore, a new method was adopted to introduce a gas-liquid-solid optofluidic microreactor with gas-liquid two-chambers into the photocatalytic nitrogen fixation reaction, and a novel and efficient TiO 2−x -Ag@HKUST-1/ carbon paper composite membrane was successfully synthesized. The porous structure of HKUST-1/carbon paper can well adsorb N 2 , and the uniformly dispersed Ag and Ti3+ in the TiO 2−x are bridged by O vacancies to form the Ti3+-Ov-Ag active center. These together improve the activity of photocatalytic nitrogen fixation to ammonia. The experimental results show that the TiO 2−x -Ag@HKUST-1/carbon paper composite membrane can continuously reduce N 2 to ammonia under visible light, and the yield can reach 10.62 mg.h-1.g cat -1and the corresponding apparent quantum yield (AQY) under 450 nm illumination reaches 2.08%, which is much higher than that of commercial TiO 2 (P25), HKUST-1, and also higher than most of the reported TiO 2 -based photocatalysts. This shows the superiority of the gas-liquid two-chambers gas-liquid-solid optofluidic microreactor in photocatalytic nitrogen fixation.This work can also be seen as a step towards the development of high-efficiency continuous photocatalytic nitrogen fixation to ammonia technology. [Display omitted] • The gas-liquid-solid optofluidic microreactor with gas-liquid two-chambers was introduced into the photocatalytic nitrogen fixation reaction. • The uniformly dispersed Ag and Ti3+ in the TiO 2−x are bridged by O vacancies to form the Ti3+-Ov-Ag active center. • The TiO 2−x -Ag@HKUST-1/carbon paper composite membrane can continuously reduce N 2 to ammonia, and the yield can reach 10.62 mg.h-1.gcat-1. [ABSTRACT FROM AUTHOR]

High-performance N-doped carbon quantum dots (NCQDs) were synthesized by a proposed green route based on hydrothermal treatments using waste paper and urea as C and N sources. The single-crystalline NCQDs demonstrated strong blue-green luminescence with the maximum intensity enhancement of 6.5 times when compared with undoped CQDs under UV and visible light excitations. XPS spectra results suggested that the enhanced photoluminescence might be attributed to pyridinic N, which could be controlled by adjusting hydrothermal temperature, time, and urea concentration. The NCQDs having excellent optoelectronic properties were fabricated into broadband photodetectors by incorporating ZnO nanorod arrays. Owing to the NCQDs, the detectors demonstrated broadband photoresponse with significantly enhanced photoresponsivity, faster response, and better sensitivity in visible range. The work provides a low-cost, environment friendly route to fabricate excellent NCQD-based broadband photodetectors for various technological applications. Image 1 • High-performance NCQDs were synthesized by a proposed green route using waste paper and urea. • A broadband photodetector was achieved by incorporating the NCQDs and ZnO nanorod arrays. • The photodetector demonstrated enhanced photoresponsivity and response rate in UV and visible range. • The mechanism for the enhanced performance was investigated. • The work provides a low-cost, environment friendly route to fabricate excellent broadband photodetectors. [ABSTRACT FROM AUTHOR]

In this paper, we have developed a paper-based optical imaging material responding to visible light. This material consists of a thioxanthone (TX) derivative with the additional phenyl carbazole chromophore, namely 1-phenyl-11,12a-dihydrothiochromeno (3,2-b) carbazol-13 (5H)-one (TX-PC), and leuco crystal violet (LCV). TX-PC is newly synthesized and characterized by 1 HNMR, FTIR and high-resolution mass spectrometer. As a visible light absorbing Type II photoinitiator, TX-PC has an excellent absorption property in the visible region in the absence of an added co-initiator. In other words, TX-PC degrades into lively free radicals when irradiating under visible light which resulting in a color reaction on LCV. The degree of reaction is characterized by UV–vis spectrophotometer. In this study, this material is used for imaging within visible light because of the high efficiency color reaction. We coat a paper substrate with this TX-PC/LCV solution and cover with a pattern photomask. Under the irradiation of the visible light, color reaction occurs to irradiated area while the rest remains colorless. Thus the two areas are distinguished to obtain a clear image as same as the original version. [ABSTRACT FROM AUTHOR]

Active packaging containing photocatalyst is generally used to solve the issues of loss and quality deterioration of fresh fruits. However, only ultraviolet (UV) light can activate these photo-catalysts in ethylene photo-degradation. To overcome this limitation, green synthesized silver nanoparticles (AgNPs) that inhibits ethylene gas production under visible light has been developed. In this study, spent green tea was mixed with deionized water at various ratios ranging from liquid to solid to obtain spent green tea extract (ex-SGT) having different concentrations used for synthesis of AgNPs. The results indicated that a good distribution of particles with a bandgap energy of 2.17 eV which was in the visible region for ethylene photo-degradation was successfully obtained with the synthesized AgNPs-60 (ex-SGT at the ratio of 60:1). The coated paper possessed an antibacterial activity and decreased the ethylene concentration in mango's packaging. Based on the finding in this work, it appears that the coated paper could have potential to be used for novel packaging of fruits to delay their ripening so that their freshness can be maintained. ga1 • Coated paper with AgNPs was green synthesized using spent green tea. • AgNPs can degrade ethylene gas via photocatalytic reaction under visible light. • Coated paper possessed an anti-bacterial activity and ripening delay of fruit. [ABSTRACT FROM AUTHOR]

Abstract: Combining microfluidic paper-based analytical device (μ-PAD) and the molecular imprinting technique, a visible light photoelectrochemical (PEC) sensing platform for the detection of pentachlorophenol (PCP) was established on gold nanoparticles (AuNPs) decorated paper working electrode using polypyrrole-functionalized ZnO nanoparticles. Ascorbic acid (AA) was exploited as an efficient and nontoxic electron donor for scavenging photogenerated holes under mild solution medium and facilitating the generation of stable photocurrent. The microfluidic molecular imprinted polymer-based PEC analytical origami device is developed for the detection of PCP in the linear range from 0.01ngmL−1 to 100ngmL−1 with a low detection limit of 4pgmL−1. This disposable microfluidic PEC origami device would provide a new platform for sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world. [Copyright &y& Elsevier]

The decolorization of Reactive Red 195 (RR195) by the oxalate catalyzed photoelectro-Fenton (PEF) process using carbon paper electrode as a cathode under visible light was studied. Comparison between electro-Fenton (EF), PEF, and PEF/oxalate processes for the removal of RR195 showed that color removal follows in decreasing order: PEF/oxalate > PEF > EF. Response surface methodology (RSM) was used to determine the effects of the four main independent parameters (initial dye, oxalate and Fe concentrations, and reaction time) on decolorization efficiency. A high coefficient of determination value ( R = 0.963) has resulted from the analysis of variance (ANOVA). The optimum values of the initial Fe concentration, the initial amount of oxalate, the initial dye concentration, and the reaction time were found to be 0.3 mM, 0.6 mM, 20 mg/L, and 120 min, respectively. A high decolorization efficiency (>93 %) was experimentally obtained for RR195 under the established optimum conditions. The response surface plots were employed to establish the effect of experimental parameters on the decolorization efficiency. These results clearly indicated the success of RSM as a suitable method for optimizing the operating conditions. The mineralization of the dye was investigated by total organic carbon (TOC) measurement. 96.2 % mineralization of 50 mg/L RR195 was observed at 9 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel dual-functional probe FAHK was design and synthesized based on copper peptide backbone. • FAHK showed sequential response towards Cu2+/Hg2+ and S2− via fluorescent and colorimetric methods. • The detection limit of 37.1 nM for Cu2+, 20.8 nM for Hg2+ and 0.27 μM/0.12 μM for S2−, respectively. • FAHK has low toxicity and was successfully used to image Cu2+, Hg2+ and S2− in living cells. • Test strips of FAHK were prepared for rapid and visual detection for Cu2+, Hg2+ and S2− with naked eye. In this study, a novel peptide-based fluorescent and colorimetric dual-functional probe (FAHK) was designed and synthesized by simulating the structure of copper peptide. FAHK exhibited high selectivity and rapid response to Cu2+ and Hg2+ with two non-fluorescence ensembles FAHK- Cu2+ and FAHK- Hg2+ formation by the 2:1 coordination mode, and the limits of detection for Cu2+ and Hg2+ were 37.1 nM and 20.8 nM, respectively. FAHK showed a naked eye colorimetric response for Cu2+ and Hg2+ in an aqueous solutions under visible light. As two new promising cascade probes, FAHK- Cu2+ and FAHK- Hg2+ ensemble were used for sequential selective recognition of S2− according to the displacement approach with fluorescence "turn-on" response and colorimetric change, and the limit of detection were 0.27 μM (FAHK -Cu2+ ensemble) and 0.12 μM (FAHK -Hg2+ ensemble) for S2−, which were well below the safety level the H 2 S standard in drinking waters (14.8 µM, WHO guidelines). What' more, in view of low toxicity and biocompatibility, the potential application of FAHK in biological systems was demonstrated via living cells imaging. More importantly, FAHK could also be made into the paper test strips for visual detection of Cu2+, Hg2+ and S2− with the naked eye under 365 nm UV light and visible light, which suggested that better portability and operation simplicity that is favourable for on-site analysis. [ABSTRACT FROM AUTHOR]

Combining adsorption and photocatalysis is an effective strategy for degrading organic pollutants. Here, BiVO 4 @diatomite composite photocatalyst (BiVO 4 @diatomite CP) was prepared by hydrothermal synthesis from Bi(NO 3) 3 ·5H 2 O glycerin solution, NH 4 VO 3 solution and diatomite. BiVO 4 @diatomite/microcrystalline cellulose/PVB composite fibers (BiVO 4 @diatomite/MCC/PVBCFs) were prepared from BiVO 4 @diatomite CPs, microcrystalline cellulose (MCC) and PVB ethanol solution using the electrospinning method. BiVO 4 @diatomite/MCC/PVBCFs were then mixed with pulp fibers to prepare the visible light-responsive photocatalytic paper. BiVO 4 @diatomite CP with a BiVO 4 /diatomite ratio of 6:4 had good interface states and displayed good photocatalytic activity with 64.32% degradation of methylene blue (MB) after 4 h. A PVB ethanol solution (6%) was formulated with BiVO 4 @diatomite CP and MCC to provide an ethanol spinning solution (12% solid) to prepare BiVO 4 @diatomite/MCC/PVBCFs (3:3:4). The resulting fibers had smooth surfaces, compact structures and exhibited good photocatalytic activity (66.80% and 56.80% degradation of MB and formaldehyde (HCHO), respectively, after 4 h). Photocatalytic paper containing 18% BiVO 4 @diatomite/MCC/PVBCFs had good photocatalytic activity with 50.20% degradation of HCHO after 4 h. This paper also had good physical properties and has the potential to be used for the photocatalytic degradation of indoor air pollutants, such as HCHO. • Adsorption and photocatalysis synergy for degrading MB and HCHO. • High degradation rates of MB and HCHO under visible light. • More potential application fields for paper. [ABSTRACT FROM AUTHOR]

Herein, we report the development of a simple green methodology to fabricate N-doped carbon quantum dots (N-CQDs) with a high luminescence using R. graveolens leaves following the hydrothermal method. Optical, chemical, morphological, and electrochemical properties were thoroughly investigated employing a variety of analytical techniques. The fabricated N-CQDs have a spherical shape, with an average diameter of 4.5 nm. Excitation dependent emission behaviour, 18% QY and green fluorescence were all observed in the N-CQDs. They are particularly resistant to various impacts such as ionic strength, pH, continuous visible light irradiation, and storage time. Since Cr(VI) ions are highly carcinogenic and mutagenic, there is an urgent demand for sensitive, selective, and efficient sensors for monitoring and measuring the amount of Cr(VI) ion in water in the environment. Hence, we developed the prepared N-CQDs as a label-free fluorescence and electrochemical probe for detecting Cr(VI) ions selectively and sensitively in aqueous solutions. Relying on static quenching together with the inner filter effect, N-CQDs performed exceptionally well as fluorescence sensors for Cr(VI) ions. The N-CQDs exhibit a limit of detection of 300 and 5 nM in the photoluminescence and differential pulse voltammetry analysis, respectively. The detection of Cr(VI) ions in real water samples using the developed sensor through both methods presented high precision without any interference. In addition, we also developed paper sensing strips for field application by depositing N-CQD on filter paper, which has been satisfactorily evaluated for sensing Cr(VI) in solid-state and solution mediums. [Display omitted] • Facile and green synthesis of N-CQDs from Ruta graveolens leaves with a QY of 18%. • Behave as an effective fluorescent sensor for Cr(VI) ions with the LOD of 300 nM. • Acts as an electrochemical sensor for Cr(VI) ion with a LOD of 5 nM. • Fluorescent paper strips were fabricated to detect Cr(VI) ions easily and rapidly. • The dual sensor exhibits excellent detection ability in real sample analysis. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• CdSe/ZnS QDs exhibited remarkable Hg2+-enhanced photocatalytic activity for TMB oxidation under visible light. • A signal-on paper-based colorimetric device for Hg2+ detection was established. • A detection limit of 0.09 μM and a wide linearity of four orders of magnitude were achieved. • The device was applied for real samples including tap water and cosmetics. CdSe/ZnS quantum dots (QDs) and 3,3,5,5-tetramethylbenzidine (TMB) were incorporated into a filter paper to produce a paper-based colorimetric device for Hg2+ detection. Under visible light, the CdSe/ZnS QDs acted as a photocatalyst to oxidize TMB, resulting in blue colorization on the paper. Moreover, Hg2+ could enhance the photocatalytic activity of CdSe/ZnS QDs and consequently caused an increase in the color intensity of the paper. The color change of the paper-based device can be directly identified by naked-eye observation or captured by a smartphone and analyzed using image processing software for quantitative analysis. Under optimal conditions, a low detection limit of 0.09 µM was achieved. This device was applied for real samples, including tap water and cosmetics, and achieved satisfying results. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are three-dimensional (3D) quantum confinement materials with confined size on the nanoscale. They are semiconductors, possessing a tunable energy gap in the range of visible light energy. In QDs, the 3D quantum confinements of excitons result in tunable fluorescence emission relying upon the QDs size and shape when excited by monochromatic light. Besides, the attempts to improve their outstanding optoelectronic properties, i.e. superior to those of bulk, thin-film semiconductor and organic dyes, many efforts have been conducted, in recent times, regarding sustainable QDs synthesis aiming at biocompatibility and cost reduction. Among the green synthesis routes of QDs there are two distinguished; namely inorganic QDs and carbon-based QDs. The first route is made of low-bandgap metal chalcogenide either extracted from a living being, e.g. earthworm, or capped with an organic ligand. While, the second route is made of carbon-core and passivating the surface with different functional groups, namely carboxyl, hydroxyl, in addition to amine. These functional groups are derived from coke or organic carbon reservoir, i.e. fruits and their juice, animal, vegetable, spice and waste paper. Numerous fundamental applications of QDs, such as biomedicine, sensing, catalysis, and solar cells, exploit the characteristic fluorescence emission of QDs, quantum yields and their modulation upon interaction with the external environment. In this review, two prototype QDs examples are used to highlight the route to sustainable QDs synthesis and solar cells implementation and some perspectives. [ABSTRACT FROM AUTHOR]

A novel scheme of projection film screen to get ultra large color gamut using photonic band gap reflection mechanism is proposed. The projection screen made by a kind of film that can only reflect three narrowband R/G/B light emitted from projector (E.g., 460nm, 560nm and 650nm), as well as absorb other visible light wavelengths. The film has a well‐designed nano level multilayer structure which can form three photonic band gaps to reflect 460nm, 560nm and 650nm light respectively. An ultra large color gamut of 73.44% Rec2020 (138.68% sRGB) was obtained even under a bright room ambient light, that makes projection image quality comparable to a traditional TV. It could be an effective way to help solve the problem of dull color performance shown on traditional projection screens. [ABSTRACT FROM AUTHOR]

In order to possess narrow passband and high transmittance at the center wavelengths of three primary colors, a three-cavity Fabry–Perot (FP) color filter is proposed whose center wavelengths are 700 nm (red), 546.1 nm (green) and 435.8 nm (blue) respectively. Through simulation, it is found that when the green color filter is in the middle, the transmission peaks only appear at the wavelength of three primary colors in the visible light range. And the structure of green color filter in the middle is designed as LH 6 2 L HL 6 while the structure of red and blue color filters on both sides is HL 6 2 H LH 6 to avoid high transmission peaks other than the center wavelengths of three primary colors caused by the 2H half-wavelength layer at the junction after combination. On this basis, the film thickness has been optimized to improve the transmittance at the wavelengths of the three primary colors and suppress the transmittance at other wavelengths. Through simulation analysis, it can be seen that the transmittance of the improved filter with optimized film thickness reach 99.64%, 96.77% and 92.94% at the wavelengths of 700.6 nm, 545.8 nm and 434.8 nm, and the full width at half maximum (FWHM) are 2.1 nm, 4.5 nm and 3.1 nm respectively. Compared with a three-primary-color filter based on grating structure, photonic crystal and metal film plasmonic, the three-cavity FP color filter proposed in this paper has not only higher transmittance at the center wavelengths of three primary color but also very narrow FWHM, which is 1–2 orders of magnitude lower than the former. Due to its superior performance, simple structure and convenient design, the filters of this structure are expected to be widely applied in display technology, color synthesis and modulation. [ABSTRACT FROM AUTHOR]

Person re-identification, as an essential research direction in intelligent security, has gained the focus of researchers and scholars. In practical scenarios, visible light cameras depend highly on lighting conditions and have limited detection capability in poor light. Therefore, many scholars have gradually shifted their research goals to cross-modality person re-identification. However, there are few relevant studies, and challenges remain in resolving the differences in the images of different modalities. In order to solve these problems, this paper will use the research method based on the attention mechanism to narrow the difference between the two modes and guide the network in a more appropriate direction to improve the recognition performance of the network. Aiming at the problem of using the attention mechanism method can improve training efficiency. However, it is easy to cause the model training instability. This paper proposes a cross-modal pedestrian re-recognition method based on the attention mechanism. A new attention mechanism module is designed to allow the network to use less time to focus on more critical features of a person. In addition, a cross-modality hard center triplet loss is designed to supervise the model training better. The paper has conducted extensive experiments on the above two methods on two publicly available datasets, which obtained better performance than similar current methods and verified the effectiveness and feasibility of the proposed methods in this paper. [ABSTRACT FROM AUTHOR]

In the dynamic landscape of 6G and smart cities, visible light communication (VLC) assumes critical significance for Internet of Things (IoT) applications spanning diverse sectors. The escalating demand for bandwidth and data underscores the need for innovative solutions, positioning VLC as a complementary technology within the electromagnetic spectrum. This paper focuses on the relevance of VLC in the 6G paradigm, shedding light on its applicability across smart cities and industries. The paper highlights the growing efficiency of lighting LEDs in infrastructure, facilitating the seamless integration of VLC. The study then emphasizes VLC's robustness in outdoor settings, demonstrating effective communication up to 10 m. This resilience positions VLC as a key player in addressing the very last meter of wireless communication, offering a seamless solution for IoT connectivity. By introducing a freely available open-source simulator combined with an alternative waveform, UFMC, the study empowers researchers to dimension applications effectively, showcasing VLC's potential to improve wireless communication in the evolving landscape of 6G and smart cities. [ABSTRACT FROM AUTHOR]

Two typical molecular switches of spiropyran (SP) and benzoxazine (OX) were fused by sharing an indole to achieve a new dual‐addressable molecular switch (SP‐OX‐NO2). Through proper molecular modification with NO2, the transformation from merocyanine (MC) to ring‐closed SP or ring‐closed OX can be controlled separately with visible light or base stimuli in solution, respectively, and these processes are verified by UV‐vis and NMR spectroscopy as well as control experiments. The cis‐merocyanine (cis‐MC) form is involved in the basochromic process in solution. DFT calculation suggests that the bidirectional switching property of the fused SP‐OX molecular switch can be controlled separately, when the OX isomer is more stable than the deprotonated SP isomer. Because of the significant color variations in solution, the simple dual‐addressable switch has been further successfully applied to construct a multicolor reversible display on paper. [ABSTRACT FROM AUTHOR]

This study examines the intriguing peculiarities of the surface paint layer found in the painting Village scene (1931) by renowned Singapore artist Liu Kang (1911–2004). The incorporation of non-invasive visible light (VIS) and near-infrared (NIR) photography techniques, combined with high-power digital microscopy, revealed unusual features on the surface paint layer. Flattened impastos, clusters of incrusted foreign paint unrelated to the existing paint scheme, and fragments of paper with printed traditional Chinese characters were identified on the painting's surface. The results of the analyses cross-referenced with the archival photographs enabled the consideration of the specified features of the paint layer as unintentional damage caused by the artist due to inadequate storage and transportation conditions—paradoxically, in his attempt to protect the painting. As these damaged areas pose potential display and conservation problems, three conservation strategies were proposed based on ethical guidelines formulated by various governing bodies for the conservation profession. This study demonstrates that there is no universal conservation solution that can satisfy conflicting aesthetic and ethical opinions. The damage to the paint layer affects the visual properties of the artwork but also provides evidence of its complex history. In light of the above, there may be valid arguments both for returning the painting to its original state and for preserving its current condition. Therefore, good practice would require balanced judgments from conservators and curators, considering Village scene in the broader context of Liu Kang's early painting practice and the existing archival information about the artist. [ABSTRACT FROM AUTHOR]

The interaction of plasmonic nanoparticles with a dielectric platform gives rise to unique optical behaviors and this can be maneuvered to improve the plasmonic/SERS performances of a substrate. Herein, dielectric modified plasmonic-paper SERS substrate is developed by assembling Ag@SiO 2 nanocubes on Fe-TiO 2 nanosheets (NS) modified paper. The Fe-TiO 2 NS being visible light responsive significantly alters the optical property of the paper and serves as a dielectric underlay for the Ag nanocubes. Hence, the incident light reflected back from the dielectric nanosheets couples with the scattered light from the Ag nanocubes leading to spatially enhanced electromagnetic field improving the SERS enhancement. The prepared dielectric modified plasmonic-paper has an average enhancement factor (EF) of 1.49 × 107 using R6G as a probe molecule. This value is superior to unmodified plasmonic-paper highlighting the coupling effect of the dielectric nanosheets. The substrate shows robust detection performance for thiabendazole and achieves a limit of detection (LOD) of 19 μg/L, which is 4-fold more sensitive than unmodified plasmonic paper. Direct swabbing test of thiabendazole sprayed apple fruit shows a discernible Raman signal down to 15 ppb indicating the utility of the substrate for point-of-need applications in food safety. Unlabelled Image • Dielectric modified plasmonic paper renders improved SERS performance. • Ag@SiO 2 NCs on Fe-TiO 2 NS modified miniaturized paper platform. • Average EF 1.49 × 107 using R6G as a probe molecule • Down to 19 μg/L thiabendazole is detected. [ABSTRACT FROM AUTHOR]

Small UAV target detection and tracking based on cross-modality image fusion have gained widespread attention. Due to the limited feature information available from small UAVs in images, where they occupy a minimal number of pixels, the precision required for detection and tracking algorithms is particularly high in complex backgrounds. Image fusion techniques can enrich the detailed information for small UAVs, showing significant advantages under extreme lighting conditions. Image registration is a fundamental step preceding image fusion. It is essential to achieve accurate image alignment before proceeding with image fusion to prevent severe ghosting and artifacts. This paper specifically focused on the alignment of small UAV targets within infrared and visible light imagery. To address this issue, this paper proposed a cross-modality image registration network based on deep learning, which includes a structure preservation and style transformation network (SPSTN) and a multi-level cross-attention residual registration network (MCARN). Firstly, the SPSTN is employed for modality transformation, transferring the cross-modality task into a single-modality task to reduce the information discrepancy between modalities. Then, the MCARN is utilized for single-modality image registration, capable of deeply extracting and fusing features from pseudo infrared and visible images to achieve efficient registration. To validate the effectiveness of the proposed method, comprehensive experimental evaluations were conducted on the Anti-UAV dataset. The extensive evaluation results validate the superiority and universality of the cross-modality image registration framework proposed in this paper, which plays a crucial role in subsequent image fusion tasks for more effective target detection. [ABSTRACT FROM AUTHOR]

This paper presents an indoor positioning strategy based on Visible Light Communication that relies on LED luminaires as transmitters, whose luminous flux is modulated at different frequencies, and a light sensor as a receiver. Then, a previously trained Artificial Neural Network (ANN) uses the illuminance signal gathered by the receiver as input to estimate the sensor's position. The main contribution of the technique is that the ANN is trained by using an illuminance estimator based on the lighting distribution of the luminaires, which is obtained through the IES file provided by the luminaire's manufacturer, without the need to collect data from the environment. In this work, the designed illuminance estimator is validated by comparing it to the well-known commercial software DIALux and Relux. The algorithm's setting and the performance evaluation of the ANN are explained. Then, the impact of the lighting uniformity and the environment's number of divisions on the accuracy of the results is analyzed. Error analyses are also made by adding uncertainty to the illuminance measurements obtained by the sensor. Finally, the work is compared to several papers in the field. [ABSTRACT FROM AUTHOR]

Solid‐state materials with reversible properties are highly attractive, owing to versatile applications in security, sensors, bioimaging, and information storage. Unfortunately, obtaining these materials in the solid state remains a huge challenge. Efficient isomerization usually requires sufficient conformational freedom and cannot be achieved without solvents or matrices. In this study, four structurally simple spiropyran derivatives are prepared that show excellent reversible photochromism under solvent‐free conditions. The large free volumes induced by different rigid aromatic ring groups enable an efficient photoswitching between closed‐ring compounds and their photoisomers. Furthermore, these compounds exhibit mechanochromic properties upon application of a mechanical force. Their color can be maintained for at least 2 days without fading under visible light irradiation at 30 °C, and can be easily erased by heating at 60 °C for 5 min. At least 30 consecutive print–erase cycles can be performed without apparent fatigue. The excellent solid‐state photochromic properties of the present compounds can find application in both UV printing and rewritable paper. [ABSTRACT FROM AUTHOR]

Conventionally, highly conductive reduced graphene oxide (rGO) is synthesized by chemical reduction of graphene oxide (GO) solution using strong toxic reducing agents. However, GO itself is synthesized using strong acids and oxidants, with repetitive cleaning and laborious steps. To overcome such challenges, this work demonstrates a novel solution to the age-old rGO synthesis route by proposing a GO free, single-step, and ultrafast rGO fabrication on paper via blue light laser irradiation, named LIrGO, for direct use in papertronic applications. Such LIrGO was thoroughly characterized, and the results were completely consistent with the conventional approach. Without any post-processing, like thermal heating or cleaning, a high carbon to oxygen ratio (7.1), narrow microfibres with mesoporous granular linked morphological structure, good electrical conductivity, and minimal sheet resistance of about 23 Ω sq−1 were obtained within few minutes based on design dimensions. With such LIrGO, various circuits and complex designs can be printed directly on paper, leading to realize environmentally friendly papertronic devices. Herein, a paper-based capacitive touch sensor was validated for excellent touch response. Further, the resulting LIrGO on paper can be hand-scraped to create composite materials for other applications. The scrapped LIrGO was leveraged to investigate the absorption capacities of PVA/rGO/Sponge and rGO/Sponge coatings over a few cycles for selective separation of oil from an oil-water emulsion. The proposed method is a beginning for a new era of rGO fabrication at a single-step avoiding all the toxic chemical routes. [Display omitted] • For the first time, production of reduced graphene oxide (rGO) without graphene oxide or graphite has been demonstrated. • Blue Diode Laser was irradiated to produce rGO on paper substrates with the desired designed patterns. • The one-step efficient approach avoids toxic chemicals and tedious processes. • The proven applications include environmentally friendly papertronic devices, capacitive touch sensor and an effective oil-water separation. [ABSTRACT FROM AUTHOR]

Exploring novel photoactive materials with high photoelectric conversion efficiency plays a crucial role in enhancing the analytical performance of paper-based photoelectrochemical (PEC) biosensor. SnO 2 , which possesses higher photostability and electron mobility, can be regarded as a promising photoactive material. Herein, paper-based one dimensional (1D) domed SnO 2 nanotubes (NTs) have been developed with the template-consumption strategy. What's more, their growth mechanism has also been proposed based on the controllable experiments. At first, the paper-based 1D ZnO nanorods (NRs) as the typical amphoteric oxide are prepared and serve as the sacrifice templates which can be etched by the generated alkaline environment during the formation of SnO 2. At a certain stage, all the ZnO NRs can be completely etched by controlling the experimental conditions, resulting in the forming of vertically distributed hollow SnO 2 NTs. Furthermore, the Sn self-doping strategy is also proposed to suppress the recombination of charge carriers and broaden the light response range by introducing the impurity energy levels. Profiting from such doping strategy, the prominent photocurrent signal is obtained compared with pure paper-based SnO 2 NTs. Ultimately, an innovative visible light responsive paper-based Sn-doping SnO 2-x NTs are developed and employed as the photoelectrode for the PEC biosensor using the alpha fetoprotein (AFP) as the model analyte. Under the optimal conditions, the ultrasensitive AFP sensing is realized with the linear range and detection limitation of 10 pg mL-1 to 200 ng mL-1 and 3.84 pg mL-1, respectively. This work provides a judiciously strategy for developing novel photoactive materials for paper-based PEC bioanalysis. • A visible light-responsive paper-based photoelectrochemical biosensor is constructed. • Paper-based one dimensional domed SnO 2 nanotubes have been developed with the template-consumption strategy. • Sn self-doping strategy is proposed to widen the light absorption range and promote the carrier separation of SnO 2 nanotubes. [ABSTRACT FROM AUTHOR]