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• New flame-resistant coatings with high mechanical properties for bagasse paper were synthesized using,3-di-aryl-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane, starch, CaCO 3 , NaHCO 3. • The thermal properties of all specimens were measured. • The ignition properties as the flame chamber (UL/94), and limiting oxygen index (LOI) was measured according to standards. This work aimed to enhance the thermal and mechanical properties of bagasse paper by synthesizing new coatings to prevent bagasse paper from the ignition. Paper sheets were treated with 0.5 percent cychlodiphosph(V)azane/ CaCO 3 solution (1.5 percent), 1.5 percent NaHCO 3 solution, and CNCs mixed with 5.0percent of starch. Paper sheets were treated by immersing bagasse paper in a coating mixture. The paper sheets were then allowed to air dry at ambient temperature. It is important to measure the burning rate (BR) to give people a chance to decrease the loss. These enhancements were investigated using elongation and tensile strength, air permeability test, Fourier Transform Infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and combustion tests (UL/94 and LOI). So, the bagasse paper treatments can be used as packaging materials. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers (CNFs) have great potential to be a layer in packaging materials because of their good barrier properties. When paper is coated with CNFs, they are difficult to distinguish from the base sheet. This issue creates challenges when trying to determine where CNFs migrate relative to the paper fibers during coating and drying. A three-dimensional analysis is possible by using confocal laser scanning microscopy (CLSM) if CNFs can be tagged with fluorescently active groups. In this study, CNFs were fluorescently tagged through adsorption of fluorescent dyes such as fluorescein isothiocyanate (FITC) and thioflavin by mixing with CNFs in their native suspension followed by purification. The adsorbed dye remained attached during typical coating procedures, low pH values, and high ionic strengths, but not for high pH and in contact with acetone. CNFs were also covalently tagged with FITC following methods reported in the literature as a comparison to already established methods for tagging cellulose nanocrystals. Images of never dried samples indicated that covalently tagging CNFs altered the state of the fines dispersion, while dye adsorption did not. Coatings of the adsorbed dye tagged CNFs on paper were successfully imaged by CLSM since the concentration of dye in the water phase was low enough to provide a good contrast between regions of CNFs and paper. With this method, the location and potential migration of CNFs coated on paper were successfully determined for the first time to the best of our knowledge. CNF based coatings with solids larger than 2.8% were found to have a distinct layer of CNFs at the paper surface with little CNFs penetrating into the paper structure, but lower solids result in significant penetration into the paper. [ABSTRACT FROM AUTHOR]

Metal halide semiconductors have huge potential on X‐ray detection, due to their high atomic number, adjustable photoluminescence wavelength, superior stability, and simple fabrication process. Here, cesium lead halide nanocrystals (CsPbX3 NCs) are fabricated on paper substrate as scintillator screen for the first time. By means of all‐solution processed spray‐coating method with optimization of polymethyl methacrylate, large‐area (>600 cm2) and low‐cost (0.0975 dollar cm−2) flexible scintillator screens are obtained with high resolution (≈5 lp mm−1), low detection limit (2.97 μGy s−1), high light yield (≈30000 photons/MeV), and fast response speed (<15 ms). The screen can achieve high‐resolution X‐ray non‐distortion imaging for non‐planar objects and realize battery check and safety monitoring at a broad range of photon energy (10–160 keV). In addition, real‐time dose rates can be easily estimated through counting the luminous arcs of the designed visible indicator. More important, the screen shows remarkable tolerance to high‐dose X‐ray radiation (tolerance over 60 Gyair continuous radiation with only 3% performance degradation), water soaking (2000 h), and conventional storage (over 300 days without apparent deterioration under ambient conditions). Hence, this work may provide huge potential in the field of medical diagnosis, non‐planar detection, and safety monitoring in the future. [ABSTRACT FROM AUTHOR]

Nanocrystalline cellulose (NCC) was prepared from office waste paper (OWP) by sulfuric acid hydrolysis method in this paper and it was used to prepare a series of poly (lactic acid) PLA/NCC composites by using a dissolution method in solvent N, N‐dimethylformamide solution. The results indicated that with the addition of only 3 wt% NCC, the composites exhibited outstanding mechanical property. The tensile, bending and impact properties of the PLA/3NCC composite were improved by 8.2%, 13.1%, and 35.9% than those of pure PLA, respectively. On this basis, office waste paper fibers (OWF) were also used as a physical blended filler to enhance PLA/NCC composites to reduce the preparation cost of PLA composites and the perfect PLA/NCC/OWF sample was easily manufactured by melting–blending and injection molding. According to the crystallization and melting performance table, both NCC and OWF can act as nucleating agent to promote the crystallization properties on composites, while the blends did not have positive effect on thermal stability. Furthermore, the water absorption and degradation properties of PLA composites were also studied. This work not only provided a novel idea for the utilization of office waste paper but also successfully produced environment friendly composites with favorable mechanical properties and crystallization performance. [ABSTRACT FROM AUTHOR]

The use of nanocelluloses as strength-enhancing additives in papermaking is widely known since both cellulose nanofibers (CNF) and nanocrystals (CNC) present similar composition than paper but their exceptional properties in the nanometer scale confers a paper quality enhancement. However, some agglomeration problems in CNF and CNC through hydrogen bonding cause a lower improvement of mechanical properties of paper. Therefore, a better dispersion of both nanocelluloses can maximize their effect on paper properties, thus reducing the needed dose to get the same increment in tensile strength and then reducing material costs. To ease the implementation of these nanocelluloses in the production process of recycled paper, typically used operations of these industries have been used. Among them, those devoted to improve the homogeneous mixture of nanocellulose in the pulp suspension have been assessed. Firstly, pulping conditions were studied, including pulping time, temperature and need for soaking as variables. Secondly, some dispersing agents used in papermaking were considered, studying the effect of different types and doses. The highest tensile strength of paper was achieved by applying long pulping times (60 min), getting increments up to 30% with the use of soaking and polyacrylamide as retention system. However, with the use of a low dose of a dispersing agent (0.003%), tensile index can be still increased up to 20.6% avoiding these long times. This study can be of great interest of those researchers trying to implement the use of nanocelluloses as strength additive in papermaking. [ABSTRACT FROM AUTHOR]

Pristine titanium dioxide (TiO2) changes color from white to black when it is reduced from TiIV to TiIII by photoexcited electrons. However, the black coloration requires substantial light energy to create, and it vanishes instantaneously upon exposure to air. This work reports the synthesis of surface‐functionalized N‐doped TiO2 nanocrystals that rapidly change color (i.e., within seconds) from whitish to black under low‐power irradiation with excellent color stability in atmospheric conditions. The N‐doping plays a critical role in promoting the surface‐adsorption of polyol groups to stabilize the TiIII species and accelerate the coloration process. A rewritable paper fabricated using these nanocrystals exhibits excellent writing and erasing reversibility in response to UV irradiation and oxygen exposure. The low‐cost, rapid response, excellent reversibility, and good color stability are vital advantages of N‐doped TiO2 nanocrystals for color‐switching applications. [ABSTRACT FROM AUTHOR]

Perovskite nanocrystals (PeNCs) are promising color converters due to their high blue light absorption and narrow‐band emission. This paper reports on the bright and stable PeNCs inks for patterned green/red color conversion pixels. Inks designed to stabilize PeNCs have a shelf life of more than one month, and UV‐cured PeNCs films exhibit high color conversion efficiency and practical durability to blue light and heat. Our PeNCs inks are capable of sufficient color conversion even at high pixel resolutions and will be a viable solution for full‐color OLED and micro‐LED displays. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals are a potentially useful material for filling lacunae of documents and artworks on paper due to their high chemical stability and specific physical properties. A composite of cellulose nanocrystals with propylene glycol, methylcellulose and CaCO 3 was obtained. Chemical and physical properties of the cellulose nanocrystal-based were compared with properties of conventional papers. Samples were tested by pH measurements, infrared spectroscopy, stress–strain testing, and scanning electron microscopy. Crystallinity index of the cellulose nanocrystal-based composite paper was about three times higher than that of the reference conventional paper. Nanocrystal-based composite and conventional papers presented similarity in stress–strain behavior. The results make nanocrystal-based composite a candidate for reintegration of lacunae of documents and artworks on paper. [ABSTRACT FROM AUTHOR]

This study presents the development of a novel paper-based electrochemical device modified with pure and nickel-doped TiO 2 nanocrystals and graphene oxide to enhance its ability to detect ascorbic acid (AA). The use of nanomaterials in the fabrication of the sensor provides a high surface area-to-volume ratio, leading to an increase in the sensitivity and selectivity of the device. The nanomaterials were synthesized, and a combination with the best properties was selected for detecting AA. The morphological, structural, and electrical properties of the nanomaterials in the paper device were investigated using scanning electron microscopy (SEM), Raman spectroscopy (Raman), and cyclic voltammetry (CV), respectively. The sensor's performance was evaluated through various experiments, including cyclic voltammetry, to measure its sensitivity and selectivity in detecting AA. The results indicate that adding Ni-doped TiO 2 nanocrystals improves the sensor's sensitivity while incorporating graphene oxide enhances its selectivity. Furthermore, the sensor's performance was compared to that of other commonly used sensors, and it was found to be highly sensitive and selective. Therefore, this paper-based electrochemical sensor, modified with nanomaterials, shows great potential for detecting AA and other applications, such as environmental monitoring and medical diagnostics, due to its high sensitivity and selectivity, low cost, and ease of use. • The modification with nanomaterials enhances the sensitivity and selectivity. • The paper-based platform is cost-effective, portable, eco-friendly, and suitable for point-of-care applications. • The study demonstrates the synergy between nanomaterials. • Increasing nickel concentration improves electrical properties, however, high concentrations worsen them. • The device also has potential implications for the environmental monitoring of C Vitamin. [ABSTRACT FROM AUTHOR]

Biodegradable colloidal particle materials are becoming attractive candidates as eco-friendly chemical additives in the low-carbon economy era. However, developing cheap, stable, and efficient paper-sizing agents is still a challenging issue for both the paper-making academic community and industry. Here, an easy-fabricating, stable, and high-performance alkenyl succinic anhydride (ASA) paper-sizing emulsion that is stabilized by lauric arginate (LAE)/cellulose nanocrystals (CNCs) nanorods is developed. Furthermore, the partial hydrophobization between ASA and LAE/CNCs can be adjusted due to the partial hydrophobization between ASA and LAE/CNC nanorods, resulting in improved stability of the ASA-sizing emulsion. This novel paper-sizing emulsion is shown to have a small droplet size (0.8 μm), high hydrolysis resistance, and a high paper-sizing degree (300 s) along with a remarkable hydrophobicity contact angle of 110° for long-term storage. This work enables the realization of an interfacial self-assembled Pickering-stabilizer, which leads to an environmentally friendly, pervasive and cost-effective emulsification technique for next-generation paper-sizing additives. [ABSTRACT FROM AUTHOR]

Microfluidic paper analytical devices (μPADs) are among the most promising platforms for heavy metal ion analysis. On the other hand, achieving simple and highly sensitive analysis of μPADs is challenging. In this study, we developed a simple enrichment method for sensitive multi-ion detection utilizing water-insoluble organic nanocrystals accumulated on μPAD. By combining the enrichment method with multivariate data analysis, three metal ion concentrations in the ion mixtures were simultaneously quantified with high sensitivity owing to the sensitive responses of the organic nanocrystals. In this work, we successfully quantified Zn2+, Cu2+, and Ni2+ at 20 ng L−1 in the mixed ion solution using only two dye indicators with a larger sensitivity improvement than those reported in previous studies. Interference studies revealed possibilities for a practical application in real sample analysis. This developed approach also can be used for other analytes. [Display omitted] • Organic nanocrystals of two dyes were applied to microfluidic paper analytical devices. • The device responses to Zn2+, Cu2+ and Ni2+ were captured by a smartphone camera. • Quantitative multivariate analysis enabled simultaneous multi-ion determination. [ABSTRACT FROM AUTHOR]

Perovskite nanocrystals (PNCs) are promising fluorescent nanomaterials that have been employed in a wide range of areas. However, their applications in some specific fields, such as chem-/biosensing remain hampered due to their inherent instability to different external stimuli. Herein, we discover a novel mechanism that ethanol, a chemical that is generally thought to be detrimental to PNCs, could specifically initiate the in-situ crystallization of the precursor salts absorbed by paper fiber to yield standard CsPbBr 3 fluorescent PNCs. Based on systematical experimental verification, it is revealed that ethanol could mediate the interfacial interaction of the PNC precursor salts on the paper fiber to allow for this exceptional in-situ PNC crystallization process. Accordingly, a fluorescence turn-on mode paper sensor for rapid and high-sensitive expiratory alcohol detection is designed, which could fulfill the on-site visualized drink-driving screening requirement. Furthermore, the application of this new mechanism in multidimensional information encryption is also demonstrated. This work not only discovers a new mechanism for PNC crystallization but also expands the sensing application toolbox of PNCs. [Display omitted] • Ethanol can induce the crystallization of perovskite nanocrystals on paper fiber. • This is due to the on-paper interaction of the precursor salts induced by ethanol. • A paper sensor is developed for fluorescence turn-on expiratory alcohol sensing. • The sensor can reach the standard of drinking-driving screening. • This technique can also be used in information encryption. [ABSTRACT FROM AUTHOR]

The screen‐printing process of conductive ink can realize simple and large‐scale manufacture of micro/nano patterns for producing wearable electronic products. Herein, chitin nanocrystals (ChNCs) are used as a dispersant for the preparation of multiwalled carbon nanotube (MWCNT) ink with high viscosity and uniformity by ultrasound treatment. ChNCs can interact with MWCNT in noncovalent ways, including π–π and hydrophobic interactions. ChNCs/MWCNT (CCNT) ink does not aggregate even after standing for 3 months with a maximum MWCNT concentration of 33 mg mL−1 and dispersion efficiency of 91.1%. Using CCNT ink, a paper‐based thermoelectric generator (TEG) is manufactured by screen‐printing technology. With good thermoelectric and strain sensing properties, CCNT coated paper can stably collect human energy at room temperature to realize self‐powering. The CCNT coated paper‐based TEG can convert thermal voltage signals into musical notes, monitor the changes in human behavior and respiratory rate, and monitor joint movements. Moreover, CCNT coated paper has no cytotoxicity by CCK‐8 and live/dead staining. This work puts forward a strategy of green preparation of MWCNT‐based ink by adding renewable chitin, which opens up a new way to apply MWCNT‐based ink in self‐powering wearable multifunctional sensors. [ABSTRACT FROM AUTHOR]

The present study was aimed to develop an ultrasensitive technique for electroanalysis of ketamine; a date rape drug. It involved the fabrication of nano-hybrid based electrochemical micro fluidic paper-based analytical device (EμPADs) for electrochemical sensing of ketamine. A paper chip was developed using zeolites nanoflakes and graphene-oxide nanocrystals (Zeo–GO). EμPAD offers many advantages such as facile approach, economical and potential for commercialization. Nanocrystal modified EμPAD showed wide linear range 0.001–5 nM/mL and a very low detection limit of 0.001 nM/mL. The developed sensor was tested in real time samples like alcoholic and non-alcoholic drinks and found good correlation (99%). The hyphenation of EμPAD integrated with nanocrystalline Zeo–GO for detection of ketamine has immense prospective for field-testing platforms. An extensive development could be made for industrial translation of this fabricated device. [ABSTRACT FROM AUTHOR]

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5–12 nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus . [ABSTRACT FROM AUTHOR]

Highlights: [•] CNCC was applied to specialty paper as a strength additive. [•] CNCC improved the mechanical properties of both cellulosic and PVA fiber paper. [•] Tear index and tensile index of both papers increased stably with addition of CNCC. [•] This article provided a newly unique window of functional application of CNCC. [Copyright &y& Elsevier]

Nanocrystalline mullite has been synthesized by sintering of absorbed monophasic aluminosilicate precursors into cotton wool and filter paper cellulosic structures. Effects of molybdenum and tungsten doping on template mediated mullite at 1200°C and 1400°C have been investigated using differential thermal analysis ( DTA), X-ray diffraction analysis ( XRD), Fourier transform infrared spectroscopy ( FTIR) and field emission scanning electron micrographs ( FESEM). Microstructures of the sintered samples revealed successful replication of cellulosic structure with the formation of dense mullite phases having grain diameter in the range of 50-80 nm. Strong photoluminescence emissions in the UV and visible regions result from the oxygen vacancies and Al-O bonds present in mullite structures. [ABSTRACT FROM AUTHOR]

A general approach has been designed to blue, green, and red pigments by metal ions doping hollow TiO2. The reaction involves initial formation of PS at TiO2 core–shell nanoparticles via a mixed-solvent method, and then mixing with metal ions solution containing PEG, followed calcining in the atmosphere. The as-prepared hollow pigments exhibit uniform size, bright color, and tunable density, which are fit for electronic paper display. [ABSTRACT FROM AUTHOR]

An effective method of preparing composites containing inorganic (Ag) and organic (beeswax) particles was established in this study. Ag nanoparticles were first immobilized on the cellulose nanocrystals (CNC) during the reduction of AgNO 3 in the presence of CNC, then mixed with beeswax by high speed stirring. Scanning transmission electron microscopy (STEM) images indicated that Ag and beeswax particles were uniformly dispersed and stable in the network structure formed by CNC. Upon coating on a paper surface, a layer of beeswax film was evident based on scanning electron microscopy (SEM) images. The dynamic contact angle and antibacterial activity tests indicated that the contact angle of coated paper reached 113.06° and the growth inhibition of Escherichia coli increased to 99.96%, respectively, at a coating amount of 21.53 g/m 2 . When applied onto paper surface by coating, the CNC/Ag/beeswax composites can impact paper with antibacterial property and improved water resistance. [ABSTRACT FROM AUTHOR]

As commercial interest in flexible power-conversion devices increases, the demand for high-performance alternatives to brittle inorganic thermoelectric (TE) materials is growing. As an alternative, we propose a rationally designed graphene/polymer/inorganic nanocrystal free-standing paper with high TE performance, high flexibility, and mechanical/chemical durability. The ternary hybrid system of the graphene/polymer/inorganic nanocrystal includes two hetero­junctions that induce double-carrier filtering, which significantly increases the electrical conductivity without a major decrease in the thermopower. The ternary hybrid shows a power factor of 143 μW m−1 K−1 at 300 K, which is one to two orders of magnitude higher than those of single- or binary-component materials. In addition, with five hybrid papers and polyethyleneimine (PEI)-doped single-walled carbon nanotubes (SWCNTs) as the p-type and n-type TE units, respectively, a maximum power density of 650 nW cm−2 at a temperature difference of 50 K can be obtained. The strategy proposed here can improve the performance of flexible TE materials by introducing more heterojunctions and optimizing carrier transfer at those junctions, and shows great potential for the preparation of flexible or wearable power-conversion devices. [ABSTRACT FROM AUTHOR]

In this study, we employed nanocrystalline cellulose (NCC) as an efficient dispersant to perpare alkyl ketene dimer (AKD) emulsion. The particle size and zeta potential of AKD/NCC emulsion were measured, which were approximately 5 μm and −50 mV, respectively. The surface-sized paper possessed multiple barriers properties. The air permeability of surface-sized paper was 0.29 μm/Pa s and the sizing degree reached 42 s when the amount of sizing was 12.58 g/m 2 with a 96.83% decrease and a 40.00%, increase, respectively. Furthermore, the mechanical properties were optimal when the amount of sizing was about 8 g/m 2 . AKD/NCC emulsion acted as a good reinforcing agent in surface-sized paper. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals have been evaluated as reinforcement material in polymeric matrices due to their potential to improve the mechanical, optical, and dielectric properties of these matrixes. This work describes how high pressure defibrillation and chemical purification affect the sludge fiber morphology from micro to nanoscale. Microscopy techniques and X-ray diffraction were used to study the structure and properties of the prepared nanofibers and composites. Microscopic studies showed that the used individualization processes lead to a unique morphology of interconnected web-like structure of sludge fibers. The nanofibers are bundles of cellulose fibers having widths (5 to 30 nm) and estimated lengths of several micrometers. [ABSTRACT FROM PUBLISHER]

I would like to comment the crystallographic part of the paper by Santosh Kumor Parida and Rama Narayan Prasad Choudhary entitled 'Preparation method and cerium dopant effects on the properties of BaMnO3 single perovskite' and published in 'Phase Transitions' in September 2020 [1]. There are several errors that should be corrected, if possible. [ABSTRACT FROM AUTHOR]

ABSTRACT Cellulose nanocrystals (CNC) are isolated from office waste paper using an alkali solution and a subsequent acid hydrolysis process. The Fourier transform infrared spectroscopy and X-ray diffraction (XRD) results demonstrate that ink and fillers used in the papermaking industry are almost totally removed after alkali treatments. The XRD results show that CNCs obtained after 2 wt % NaOH solution treatment and a subsequent hydrolysis process exhibit only a cellulose I crystalline structure, and the crystallinity index value increases around 42% with respect to initial office waste paper. Nevertheless, CNCs obtained after 7.5 wt % NaOH solution treatment and a subsequent acid hydrolysis process show a mixture of cellulose I and cellulose II polymorphs. The thermal analysis shows that the CNCs obtained after 7.5 wt % NaOH solution treatment and a subsequent acid hydrolysis process are thermally less stable than other samples, suggesting that the cellulose chains could depolymerize into low molecular weight sugar compounds. Even though the atomic force microscopy images confirm the presence of CNCs, the optical images show that some cellulose microfibers still maintain their structure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45257. [ABSTRACT FROM AUTHOR]

Electrically conductive films are key components in most printed and flexible electronics applications. For the solution processing of conductive films, inks containing silver nanoparticles (AgNPs) remain important because of their relatively easy processing and generally low resistivity after a sintering procedure. Because the commonly used, moderate sintering temperatures of 150-300 °C are still too high for most low-cost flexible substrates, expanding the knowledge of surface-ink interactions that affect the sintering temperature is desirable. It is known that chloride ions can assist the sintering of AgNP films by displacing capping agents on the surfaces of AgNPs. However, very little is known about other possible Cl-AgNP interactions that affect the resistivity and no interaction having the opposite effect (sintering inhibition) has been identified before. Here we identify such a Cl-AgNP interaction giving sintering inhibition and find that the mechanism involves the formation of AgCl nanocrystals within the AgNP film. The AgCl formation was observed after inkjet-printing of AgNP inks with polyvinylpyrrolidone (PVP) as the capping agent onto papers with quick-absorbing coatings containing 0.3 wt % KCl. Our findings show that chloride can have opposite roles during sintering, either assisting or inhibiting the sintering depending on the prevalence of AgCl formation. The prevalence of AgCl formation depends on the absorption properties and the capping agent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developing a graphite nanocrystals (GNCs)/paper electrode using ion beam sputtering deposition method. • An electrochemical genosensor using the cDNA-functionalized Au@CD core/shell NPs for the SARS-CoV-2 RdRP detection. • Engineering a signal-on mechanism based on the intercalation of toluidine blue into the large grooves of cDNA-RdRP duplex. Currently, the development of biosensors is an urgent need due to the rapid spread of SARS-CoV-2 and the limitations of current standard methods for the diagnosis of COVID-19. Hence, many researchers have focused on the design of high-performance biosensors for measuring coronavirus genes. In this study, a voltammetric genosensor was developed for the determination of SARS-CoV-2 RdRP gene based on the format of cDNA probe/Au@CD core–shell NPs/graphite nanocrystals (GNCs)/paper electrode. For the first time, graphite nanocrystals were used in the electrochemical biosensor design. This genosensor was exposed to different concentrations of virus gene and then the hybridization between cDNA probe and RdRP gene was monitored by redox-active toluidine blue (TB). With increasing the RdRP concentration, the reduction peak current of TB enhanced in a linear range of 0.50 pM-12.00 nM according to the regression equation of I (μA) = 7.60 log C RdRP (pM) + 25.78. The repeatability with a RSD of 2.2% clearly exhibited that the response of modified electrode is stable because of the high adhesion of GNC layer on the paper substrate and the high stability of cDNA-Au@CD bioconjugates. The spike-and-recovery studies showed the acceptable recoveries for the sputum samples (>95%). [ABSTRACT FROM AUTHOR]

A large-area, self-supported Co3O4 nanocrystal/carbon fiber electrode for oxygen and hydrogen evolution reaction was fabricated via thermal decomposition of the [Co(NH3)n]2+–oleic acid complex and subsequent spray deposition. Due to the exposed active sites and good electrical conductivity, its operate voltage for overall water splitting is nearly the same as commercial Pt/C. [ABSTRACT FROM AUTHOR]

The article focuses on development of paper solar cell technology for addressing the need of new type of solar cell, by researchers with the Industry University Cooperative Research Center for Next Generation Photovoltaic (NGPVIUCRC). It mentions need of solar cells for internet of things (IoT) requiring devices and sensors to transmit information wirelessly to mobile personal electronics and computer networks. It also mentions the technology combining nanocellulose paper with nanocrystal ink.

Abstract: A sustainable packaging system with excellent liquid- and gas-barrier properties and enhanced strength properties was highlighted by a composite coating containing a mixture of cellulose nanocrystals (CNC), a high-aspect ratio nano-filler montmorillonite clay, an amphiphilic binder soy protein, and a surface-active agent alkyl ketene dimer. They were tested on various surfaces of commercially available packaging papers and compared with the appropriate control (i.e., CNC-only coating) to determine surface morphology, chemical composition, barrier, and mechanical properties. Scanning electron microscopy image analysis showed a compact matrix whose defects (cracks) were significantly attenuated compared to the control while FTIR showed fewer exposed hydroxyl (-OH) groups. The compact structure and reduced proportion of -OH groups are attributed to the plate-like structure, high aspect ratio of clay, and uniform distribution of additives to help inhibit gas, moisture, water, oil, and grease permeation. The base paper used also had a significant impact on how coatings interacted with various fluids. Overall, sustainable CNC-composite barrier coatings with relatively low-cost additives were fabricated and showed improved barrier and strength characteristics with a strong potential as barrier coatings for packaging.Graphical Abstract: [ABSTRACT FROM AUTHOR]

A new method for the determination of chloride anions in sweat is described. The novelty of the method relies on the different photochemical response of silver ions and silver chloride crystals when exposed to UV light. Silver ions undergo an intense colorimetric transition from colorless to dark grey-brown due to the formation of nanosized Ag while AgCl exhibits a less intense color change from white to slightly grey. The analytical signal is obtained as mean grey value of color intensity on the paper surface and is expressed as the absolute difference between the signal of the blank (i.e., in absence of chloride) and the sample (i.e., in the presence of chloride). The method is simple to perform (addition of sample, incubation in the absence of light, irradiation, and offline measurement in a flatbed scanner), does not require any special signal processing steps (the color intensity is directly measured from a constant window on the paper surface without any imager processing) and is performed with minimum sample volume (2 μL). The method operates within a large chloride concentration range (10–140 mM) with good detection limits (2.7 mM chloride), satisfactory recoveries (95.2–108.7%), and reproducibility (<9%). Based on these data the method could serve as a potential tool for the diagnosis of cystic fibrosis through the determination of chloride in human sweat. [ABSTRACT FROM AUTHOR]

Transparent TiO2and TiO2–ZrO2(molar ratio Zr/Ti = 0.1) thin films were produced by low-temperature sol–gel processing from nanocrystalline aqueous based solutions. The structural features and compositions of the films treated at room temperature, 100 °C and 500 °C were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and thermal analysis. Addition of zirconia increased specific surface area (140–230 m2g−1) and hindered the growth of anatase crystallites, exhibiting a constant size of 6–7 nm in the whole temperature range. These significant changes with respect to pure TiO2in anatase crystalline form did not result in significantly and systematically different photocatalytic activity, which was evaluated in terms of aqueous pollutant degradation (azo-dye in water) and self-cleaning ability (fatty contaminant deposit). The films treated at only 100 °C showed excellent photocatalytic activity towards azo-dye degradation. Contact angle measurements of aged and contaminated surfaces revealed a fast or sharp hydrophilicity gain under UVA illumination. Accordingly, the results of this study confirmed the potential application of advantageous low-temperature films in water treatment as well as for self-cleaning surfaces. [ABSTRACT FROM AUTHOR]

Titania nanocrystalline films have been deposited on glass slides and loaded with Pt nanoparticles by adsorption from aqueous solutions of sodium tetrachloroplatinate followed by UVA radiation or heat treatment. These metal/semiconductor combined photocatalysts have been used for photooxidation of aqueous ethanol and production of hydrogen. The efficiency of the photocatalytic process was associated with the metal load on the titania films and the size of the metal nanoparticles. Characterization of the combined photocatalyst has been made by X-ray photoelectron spectroscopy and transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Given their photoluminescent character, portable quantum dot readers are often sophisticated and relatively expensive. In response, we engineered a "do it yourself" fluorescence reader employing paper materials and a mid-range smartphone camera. Black paperboard facilitated a versatile, lightweight and foldable case; whereas cellophane paper was observed to behave as a simple, yet effective, optical bandpass filter leading to an advantageous device for the quantitative interrogation of quantum dot nanocrystals concentrations (from 2.5 to 20 nM), which are suitable for optical point-of-care biosensing. The streptavidin-coated nanocrystals employed are commercially available and the developed reader was benchmarked with a standard portable quantum dot reader, thereby demonstrating advantages in terms of cost and linear analytical range. [ABSTRACT FROM AUTHOR]

While there are many known ways to improve light extraction, however, the cost‐effective manufacturing process and the requirement to achieve high quality image severely restrict how light can be extracted. Pixelligent's solution processable high refractive index zirconia materials allow for the creation of high index, transparent, low‐haze nanocomposites that can build the necessary light extraction structures. The application of Pixelligent's PixClear® high‐refractive index (> 1.7) zirconia nanocomposite films onto glass or flexible substrates by inkjet printing is discussed in this paper. The optically clear nanocomposite formulation comprises zirconia nanocrystals (< 10 nm in diameter), a UV‐curable binder material, a high‐boiling point solvent, and with (or without) scatters. Clear films with > 90% transmission and films containing scattering particles have been printed as uniform layers and patterned structures by inkjet printing. A broad range of film thicknesses are achievable for inkjet printing, ranging as low as tens of nanometers and up to 100 microns. Main advantages of inkjet printing are the material conservation during deposition and complex patterning of the printed material. For this study, we demonstrate the ability of Pixelligent's zirconia nanocomposites to improve the light extraction and can be inkjet printed, emphasizing a new way in which high‐refractive index materials are being incorporated into devices for OLED lighting and displays. [ABSTRACT FROM AUTHOR]

The study reports on the preparation of cellulose nanocrystals (CNCs) from wastepaper, as an environmental friendly approach of source material, which can be a high availability and low-cost precursor for cellulose nanomaterial processing. Alkali and bleaching treatments were employed for the extraction of cellulose particles followed by controlled-conditions of acid hydrolysis for the isolation of CNCs. Attenuated total reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy was used to analyze the cellulose particles extracted while Transmission electron microscopy images confirmed the presence of CNCs. The diameters of CNCs are in the range of 3–10 nm with a length of 100–300 nm while a crystallinity index of 75.9% was determined from X-ray diffraction analysis. The synthesis of this high aspect ratio of CNCs paves the way toward alternative reuse of wastepaper in the production of CNCs. [ABSTRACT FROM AUTHOR]

With the rapid development of social industrialization, energy crisis and environmental problems are becoming increasingly serious. Therefore, there is an urgent need to synthesize multi-mode nanocatalysts for general application. In this paper, a h-Fe3O4@Pd/PDA nanocatalyst with Pd nanocrystals sandwiched between a h-Fe3O4 hollow sphere and a polydopamine (PDA) shell was prepared by a simple redox-oxidative polymerization method. The catalytic activity of h-Fe3O4@Pd/PDA hollow spheres was evaluated using selective reduction hydrogenation of 4-nitrostyrene, reduction of 4-nitrophenol and oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) as catalytic models. h-Fe3O4@Pd/PDA has reduction kinetics of 4-nitrophenol up to 0.77 min−1 mg−1. Importantly, the rate of 4-nitrophenol reduction catalyzed by h-Fe3O4@Pd/PDA was enhanced by 1.43 times under near infrared light (NIR, 808 nm) irradiation. In addition, NIR laser can induce the selective reduction of 4-nitrostyrene to 4-aminostyrene by h-Fe3O4@Pd/PDA with a selectivity of 84.8%. Under different reaction scenarios, h-Fe3O4@Pd/PDA hollow spheres could be recycled by magnetic recovery, and the catalytic reaction activity was above 70% after six cycles. As a result, owing to the simple fabrication, good magnetic separation and high NIR-enhanced catalytic properties, h-Fe3O4@Pd/PDA exhibited a wide range of potential in nanocatalysis. [ABSTRACT FROM AUTHOR]

We demonstrate a simple, rapid, selective and sensitive method for the detection of p-nitrophenol (pNP) using luminescent colloidal silicon nanocrystals (Si NCs). Aqueous suspension of green luminescent Si NCs was prepared at room temperature by simultaneous hydrolysis and redox reaction of (3-aminopropyl)triethoxysilane (APTES) in a remarkably simple one-step method. Trace addition of pNP significantly quenched the luminescence of the Si NCs and the quenching was found to be linearly dependent on the pNP concentration in the range of 0–20 μM of pNP in solution. Beyond 20 μM pNP concentration the quenching varied exponentially. Analysis of steady state absorption and emission, along with photoluminescence decay dynamics revealed that formation of ground state complexes (static quenching) and primary inner filter effect played a combined role in affecting quenching at relatively lower concentration range (0–20 μM); whereas both static and dynamic quenching came into effect at concentrations above 20 μM. Finally, we demonstrate a simple, pH-paper-type sensor based on Si NC coated filter paper and aluminium tape, for detection of aqueous as well as airborne pNP. [ABSTRACT FROM AUTHOR]