Search

In this work, aluminum nitride particles (AlN) and boron nitride whiskers (BN w) were surface-functionalized by polydopamine, and then novel composites were prepared by co-doping. By observing with transmission electron microscopy, we clearly saw that the surfaces of AlN and BN w were successfully coated with a thin polydopamine coating. This is beneficial to enhance the filler-matrix interface interaction and the filler dispersion. The co-doping of the two thermally conductive fillers increases the chance of contact between the filler and the filler, and reduces the interfacial thermal resistance, thereby forming a thermal conduction network more efficiently. The results show that at a frequency of 1 MHz at room temperature, the dielectric constant of 30 wt%AlN@PDA/6 wt%BN w @PDA/EP composites is 4.74 and the dielectric loss tangent is 0.0171. Its thermal conductivity is 0.40 W/(m·K), the glass transition temperature reaches 250.2°C, the impact strength reaches 6.89 kJ m−2, and the breakdown field is 10.93 kV/mm. • The addition of thermal conductive AlN@PDA and BN w @PDA with excellent heat-transfer capability significantly improves the thermo-stability of epoxy resin composites. • PDA coating effectively inhibits the agglomeration of thermal conductivity particles, and the co-doping of BN w @PDA and AlN@PDA makes it easier to form heat transfer network. • With the addition of BN w @PDA and AlN@PDA, the surrounding matrix can be bridged into a stressed whole, which markedly enhances the impact strength of the composites. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) contamination is an environmental concern that threatens the agricultural product safety and human health. To address this concern, we developed a novel strategy involving the synergistic application of Azospirillum brasilense , a growth-promoting rhizobacterium which produces abscisic acid (ABA), and biochar to minimize HM accumulation in the edible parts of vegetable crops. Compared to A. brasilense or biochar alone, the concentrations of Cd, Ni, Pb, and Zn in radish (Raphanus sativus L.), pakchoi (Brassica chinensis L.), and tomato (Lycopersicon esculentum L.) decreased by 18–63% and 14–56%, respectively. Additionally, the synergistic treatment led to a 14–63% decrease in the bioconcentration factor. The biomass of the edible parts of the three crops increased by 65–278% after synergistic treatment, surpassing the effects of single treatments. Furthermore, the synergistic application enhanced the SPAD values by 1–45% compared to single treatments. The MDA concentrations in stressed plants decreased by 16–39% with the bacteria-biochar co-treatment compared to single treatments. Co-treatment also resulted in increased soluble protein and sugar concentrations by 8–174%, and improvements in flavonoids, total phenols, ascorbic acid, and DPPH levels by 2–50%. Pearson correlation analysis and structural equation modeling revealed that the synergistic effect was attributed to the enhanced growth of A. brasilense facilitated by biochar and the improved availability of HMs in soils. Notably, although ABA concentrations were not as high as those achieved with A. brasilense alone, they were maintained at relatively high levels. Overall, the synergistic application of A. brasilense -biochar might have remarkable potential for reducing the accumulation of HMs while promoting growth and improving nutritional and antioxidant qualities in tuberous, leafy, and fruit crops. [Display omitted] • ABA-producing bacteria and biochar synergistically reduce HM accumulation in vegetables. • Increased ABA levels and reduced soil HM availability contribute to this synergistic effect. • Improved crop yields, nutritional value, and antioxidant capacities were observed. • Biochar plays a significant role in the synergy alongside A. brasilense. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Developed Poly(N-Isopropylacrylamide)-Cellulose Nanocrystal hydrogel films. • Achieved unique thermo-responsivity and tunable optical performance. • Developed a hybrid materials system to modulate LCST and moisture content for thermo-responsivity and optical tunability. • Demonstrated a ∼ 15 °C reduction of the LCST relative to pure PNIPAm hydrogel films. • Below the LCST, PNIPAm/CNC hydrogel films exhibit transparency or semi-transparency. Abstract A hybrid materials system to modulate lower critical solution temperature (LCST) and moisture content for thermo-responsivity and optical tunability was strategically developed by incorporating cellulose nanocrystals (CNCs) into a poly(N -isopropylacrylamide) (PNIPAm) hydrogel matrix. The PNIPAm/CNC hydrogel films exhibit tunable optical properties and wavelength bandpass selectivity as characterized by PROBE Spectroscopy and Dynamic Light Scattering (DLS). Importantly, the micro/nano structures of the PNIPAm/CNC hydrogel films were completely different when dried below and above the LCST. Below the LCST, PNIPAm/CNC hydrogel films exhibit transparency or semi-transparency due to the uniform bonding of hydrophilic PNIPAm and CNC through hydrogen bonds. Above the LCST, the hydrogel films engage in both hydrophobic PNIPAm and hydrophilic CNC interactions due to changes in PNIPAm conformation which lead to light scattering effects and hence opacity. Furthermore, the incorporation of CNC induces a ∼ 15 °C reduction of the LCST relative to pure PNIPAm hydrogel films. [ABSTRACT FROM AUTHOR]

Although profiles of axisymmetric capillary bridges between two cylindrical fibers have been extensively studied, little research has been reported on capillary bridges under external forces such as the gravitational force. This is because external forces add significant complications to the Laplace–Young equation, making it difficult to predict drop profiles based on analytical approaches. In this paper, simulations of capillary bridges between two vertically stacked cylindrical fibers with gravitational effect taken into consideration are studied. The asymmetrical structure of capillary bridges that are hard to predict based on analytical approaches was studied via a numerical approach based on Surface Evolver (SE). The axial and the circumferential spreading of liquids on two identical fibers in the presence of gravitational effects are predicted to determine when the gravitational effects are significant or can be neglected. The effect of liquid volume, equilibrium contact angle, the distance between two fibers and fiber radii. The simulation results were verified by comparing them with experimental measurements. Based on SE simulations, curves representing the spreading of capillary bridges along the two cylindrical fibers were obtained. The gravitational effect was scaled based on the difference of the spreading on upper and lower fibers. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) and reduced graphene oxide (r-GO) continue to attract considerable research due to their applicability in many academic and industrial fields. Here, we report a liquid-phase plasma approach with fast reduction and high reactivity for directly converting GO to r-GO at mild temperatures. The liquid-phase plasma process is at the forefront, and it is a strong candidate for facilitating large-scale applications of GO and r-GO. In this work, using methanol as an additive rather than other hazardous reducing agents, the results demonstrated that methanol could provide more hydrogen radicals (·H) to improve the reduction process of the liquid-phase plasma. Meanwhile, the ·CH 2 , ·CH, ·C, ·C 2 , ·OH, ·H, ·O were formed during discharge, suggesting that the collision of energetic electrons in plasma with methanol and water, which subsequently removes oxygen-containing functional groups and restores the π-conjugated structure in GO through a radical process. The analytical results revealed that r-GO has been successfully reduced by liquid-phase plasma. In conclusion, our findings can provide underlying insights into liquid-phase plasma treatment for GO reduction. • Microwave liquid-phase plasma approach for graphene oxide reduction. • Energetic electrons and ·H for the deoxygenation and sp2 carbon restoration. • Plasma and methanol in combination results in higher ·H reduction rates. • Future studies of simultaneous reduction and defect healing: create a paradigm. [ABSTRACT FROM AUTHOR]

Transparent and High Barrier Plasma Functionalized Acrylic Coated Cellulose Triacetate Films. • Fabrication of transparent and high barrier coated cellulose triacetate (CTA) films. • Enhanced adhesion and curing of acrylic coatings via atmospheric plasma treatments. • Significant reduction in WVTR while maintaining excellent transparency. • Modulation of surface texture via plasma compositions and crosslinking agents. Transparent and high moisture barrier acrylic coatings were obtained by deposition of acrylic resin containing crosslinking agents onto cellulose ester films, followed by exposure to atmospheric plasma. The effects of monomers, crosslinking agents, and polymerization methods were studied. The surface chemical composition, morphology, water vapor transmission rate (WVTR), light transmittance, and adhesion performance of the coated cellulose triacetate (CTA) films were characterized for the acrylic coated films and for different plasma treatments. Coated films showed a significant reduction in water vapor permeability while maintaining excellent transparency when compared with uncoated films. Furthermore, adhesion of the coating to the CTA film was also improved due to plasma treatment. It was also found that plasma curing on the coated oligomers can induce morphological changes and significantly increase surface roughness and hydrophilicity. The roughness texture observed via SEM analysis indicated that the types of plasma polymerization and the amount of crosslinking agents control the texture types for acrylic coating. Plasma-assisted acrylic coated CTA films can be used in electronic displays, medical, and packaging applications. [ABSTRACT FROM AUTHOR]

• Tunable poly(N-Isopropylacrylamide)-cellulose nanofibrils hydrogel films. • Fabrication using inverted SLA 3D printing to provide a new manufacturing platform. • Switchable bio-adhesion to bacteria depending on the CNF content and distribution. • Unique thermo-responsivity and tunable optical performance. • Modulation of LCST (∼ 8 °C reduction) relative to pure PNIPAm hydrogel films. A hybrid poly(N-isopropylacrylamide) (PNIPAm)/cellulose nanofibrils (CNFs) hydrogel composite was fabricated by inverted stereolithography 3D printing to provide a new platform for regulating lower critical solution temperature (LCST) properties and thus tuning optical and bioadhesive properties. The phenomena of interest in the as-printed PNIPAm/CNF hydrogels may be attributed to the fiber-reinforced composite system between crosslinked PNIPAm and CNFs. The optical tunability was found to be correlated to the micro/nano structures of the PNIPAm/CNF hydrogel films. It was found that PNIPAm/CNF hydrogels exhibit switchable bioadhesivity to bacteria in response to CNF distribution in the hydrogels. After 2.0 wt% CNF was incorporated, it was found that a remarkable 8°C reduction of the LCST was achieved relative to PNIPAm hydrogel crosslinked by TEGDMA without CNF. The prepared PNIPAm/CNF hydrogels possessed highly reversible optical, bioadhesion, and thermal performance, making them suitable to be used as durable temperature-sensitive sensors and functional biomedical devices. [ABSTRACT FROM AUTHOR]

• CNF/MWCNTs films with a structure of semi-interpenetrating networks were fabricated. • Percolation threshold level of CNF/MWCNTs membranes of 1.88 wt% was achieved. • CNF/MWCNTs films with 10 wt% MWCNTs showed a high conductivity value of 37.6 S/m. • Resistances of CNF/MWCNTs films were affected by bending states to a minor extent. • Capacitance of the pressure sensors was almost linearly dependent on pressure. Highly conductive multi-walled carbon nanotubes (MWCNTs) and flexible cellulose nanofibers (CNF) membranes with semi-interpenetrating networks structure were fabricated using the typical paper-making method, which was simple and cost-effective. The Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR), and thermal gravimetric analysis (TGA) were used to estimate the morphology, chemical structure, and thermal stability of the membranes. The mechanical, optical, and electrical properties of the membranes were characterized with a uniaxial tensile testing machine, ultraviolet visible spectroscope, and digital multimeter, respectively. The results indicated that the membranes containing 10 wt% of MWCNTs showed a high conductivity value of 37.6 S/m, and the sheet resistances of the membranes were stable at different bending states. Furthermore, we demonstrated the electrical features of membrane-based capacitive pressure sensors based on CNF/MWCNTs. The proposed method for fabricating CNF/MWCNTs membranes can simplify the production process and have great practical potential in various electronics applications such as touch screens. [ABSTRACT FROM AUTHOR]

Cellulose-based composites have attracted significant attention in the fabrication and advancement of wearable devices due to their sustainable, degradable, and cost-effective properties. However, achieving a cellulosic sensor with reliable sensory feedback remains challenging owing to the deficiency in reversible microstructures during response processes. In this study, we developed a piezoresistive sensor consisting of nearly pure cellulose handsheets using origami-inspired corrugated structures to achieve durable and sensitive piezoresistive responses. Multi-walled carbon nanotubes (MWCNTs) were used as conducting agents. With the addition of 7 wt% MWCNTs, 36.27 % of the cellulose fiber surface was covered and the conductivity of cellulose handsheets was increased to 8.7 S/m. The obtained conductive cellulose handsheets were transformed into corrugated structures and integrated orthogonally to construct the piezoresistive sensors with reversible electrical paths for electrons. The restorable corrugated structure endowed the sensors with a wide workable pressure range (0–10 kPa), high sensitivity (6.09 kPa−1 in a range of 0–0.92 kPa), fast response time (<280 ms), and good durability (>1000 cycles). Furthermore, the practical applications of the proposed sensors as wearable devices were demonstrated through phonation, real-time sports monitoring, and step pressure tests. [Display omitted] [ABSTRACT FROM AUTHOR]

The ethanol decomposition process for hydrogen-rich gas synthesis via microwave discharge in ethanol-water mixtures was investigated in this study. Excited active species and gas-phase products based on ethanol's varying volume fraction were detected via optical emission spectroscopy (OES) and mass spectrometry (MS). The correlation between the spectrum signal of the active species and the mass spectrum signal of the gas phase products was quantitatively analyzed. The experimental results showed that the intermediate active species mainly consisted of OH, C 2 , CH 2 , CH, C, and H, and the gas phase products mainly included H 2 , CH 4 , C 2 H 2 , CO, C 2 H 4 , and CO 2. There were significantly positive linear relationships between H or CH 2 and H 2 , demonstrating that both H and CH 2 were important radicals for generating H 2. Based on the experimental results and analyzed from the perspective of thermodynamics, the reactions of H + H (+M) → H 2 (+M) and H + H + H 2 →H 2 + H 2 , H + H + H 2 O → H 2 + H 2 O, CH 2 + CH 2 → H 2 + C 2 H 2 were all likely to produce hydrogen. • There were significantly positive linear relationships between H or CH 2 and H 2. • H and CH 2 were important radicals for generating H 2. • Possible reaction path of microwave discharge in ethanol solution was given. [ABSTRACT FROM AUTHOR]

Hydrogen produced by pulsed discharge in ethanol-water mixtures is optimized in this work. A needle-balls configuration is designed, which is fit for situ hydrogen production in transportation. The energy yield of hydrogen can attain 141.3 gH 2 /kWh, which is better than most existing methods. The high energy yield attributes to the special discharge characteristics. During the discharge, shock waves make the balls jumping in the reactor that increase the randomness and local strength of discharge. The microscopic pathway of pulsed discharge in ethanol-water mixtures is also analyzed by the comparison of rate constants. The main products can be analyzed from the microscopic pathway. In addition, CH 3 CHO, CH 2 O are important intermediates, which may be good additives for increasing hydrogen yield. • Hydrogen produced by pulsed discharge was optimized with needle-balls configurations. • The Energy yield of hydrogen can reach 141.3 gH 2 /kWh. • The microscopic pathway of pulsed discharge in ethanol-water mixtures was analyzed. • Aldehydes are important intermediates for hydrogen production. [ABSTRACT FROM AUTHOR]

Hydrogen production from ethanol solution (initial ethanol concentration of 50%) by pulsed discharge coupled with TiO 2 is investigated in this work. Strong ultraviolet light is emitted by pulsed discharge in liquid, which makes photocatalysis have a great prospect in plasma reforming. Two kinds of TiO 2 are attempted, containing non-metal ion doping and Ag deposition. The results show that the flow rate of hydrogen produced by pulsed discharge with TiO 2 coated non-metal can be achieved 1.55 L/min, which is higher than with TiO 2 coated Ag, but both two are higher than discharge without TiO 2 . From SEM analysis, it may be associated with the larger specific surface area of TiO 2 coated non-metal. However, percentage concentration of hydrogen produced with TiO 2 coated Ag is higher than others, which can be attained 78%. It may be due to the high work function of Ag. In addition, mechanism of hydrogen produced by pulsed discharge coupled with TiO 2 is also analyzed. It demonstrates that the increase of ·H is the main reason for increased hydrogen yield. [ABSTRACT FROM AUTHOR]

Carbon nanoparticles produced from alcohols by pulsed spark discharge in liquid (PSDL) was investigated in this work. The spherical carbon particles with about 10 nm diameter can be produced by PSDL, which were similar to the commercial carbon particles. With the increase of discharge power, the mean diameter of carbon particles was decreased and the size distribution was more uniform. Meanwhile, the yield of carbon produced from ethanol was more than from methanol that may be attributed to the more carbon atoms in ethanol compared with the same volume of methanol. In addition, the mechanism of carbon produced from alcohols by PSDL was also analyzed. The possible reactions were given according to the production analysis. This work presents a new method for carbon nanoparticles production and the results can play a guidance role in producing nanometer materials by plasma reforming. [ABSTRACT FROM AUTHOR]

Hydrogen produced from ethanol solution by pulsed discharge was investigated in this work. With needle-net configurations, hydrogen can be easily exported from the plasma reactor thereby preventing hydrogen from consuming by the oxidizing active substances generated from pulsed discharge. Both flow rate and percentage concentration of hydrogen were enhanced with the increase of energy density, but not much change with the increase of discharge time. Flow rate, percentage concentration, and energy consumption of hydrogen were achieved about 800 mL/min, 73.5%, and 0.9 kWh/m 3 H 2 respectively with energy density of 6.4 J/L. All products were analyzed, which were divided into main and secondary products guiding the mechanism analysis of hydrogen production. The main products contain H 2 , CO, CH 3 OH, and the secondary products include C 2 H 2 , CO 2 , macromolecular compounds, nano carbon particles. The high hydrogen yield, emerged nano carbon, low ethanol and energy consumption make this method possess bright prospect in hydrogen production. [ABSTRACT FROM AUTHOR]

Resourceful treatment of alcohol distillery wastewater by pulsed discharge in liquid (PDL) was first studied in this work. The biodegradability of alcohol wastewater can be effectively improved and chemical oxygen demand (COD) removal attained over 40% within 15 min PDL treatment. Hydrogen produced from the treating processes was emphatically analyzed. The flow rate, and yield of hydrogen achieved were 80 mL/min, 146 mL/g COD removed within 30 min respectively, which were much better than existing technologies. Meanwhile, the mechanism of hydrogen production from alcohol distillery wastewater by PDL was presented in this work indicating that different region in reactor has different mechanism. In discharge channel, high-energy electrons and resultant free radicals played a leading role. Far away from discharge channel, the neutral particles with strong oxidizing were more important. This work can be a good guidance for both treatment of refractory wastewater and mechanism of hydrogen production by plasma reforming. [ABSTRACT FROM AUTHOR]

Hydrogen-rich syngas produced from ethanol/water mixtures by pulsed electrodeless discharge is studied in this work. A plate-pinhole-plate device is used to achieve electrodeless discharge that positive and negative discharge can simultaneously generate in both sides of the pinhole. The study find that the gas production efficiency is higher when both sides are spark discharge. Among the produced gas, H 2 , CO are the main components, which account for about 99%. Meanwhile, in order to acquire hydrogen-rich syngas with high yield, both high peak voltage and appropriate electrode distance are important. The reaction process is also researched by the spectral diagnosis. The results show that the generation of ·H is the key for syngas production by pulsed electrodeless discharge that ·H is not only the important substance for hydrogen production, but also affects the generation of ·CH and ·C 2 thereby determining the CO production. • Syngas from ethanol/water mixtures by pulsed electrodeless discharge was studied. • Spark discharge on both polarities is great for syngas production. • Peak voltage and electrode distance are important for syngas production. • The generation of ·H is associated with syngas production. [ABSTRACT FROM AUTHOR]