Low Surface Research Articles

Fabrication of slanted gratings with high refractive index starting from master nanoimprint mold

Recently, nanoimprinting has attracted a new round of attention in the industry due to the boom in demand for augmented reality/virtual reality (AR/VR), metalens and microlens, and even semiconductors. Slanted gratings have great application prospects in AR/VR displays because of their high efficiency in light coupling. UV-Nanoimprint lithography (UV-NIL) has been identified as one of the most feasible routes for mass manufacture of high refractive index (RI) slanted gratings. This paper presents a fabrication of high RI slanted gratings based on UV-NIL. A comprehensive study on the optical principles of slanted gratings is conducted, followed by simulation-based optimization of the grating parameters. The key element for applying nanoimprint to fabricate slanted gratings is the master mold, which is acquired by a tilted angle etching of metal gratings as an etching mask on silicon wafers with F-based plasma. The influence of experimental parameters, such as the etching power and etching mask thickness on the morphology of the slanted gratings on the master mold are investigated. The working mold was simply duplicated from the master mold by UV-NIL with a low surface energy working mold material. The high RI slanted gratings were achieved by imprinting a UV-curable resin with high RI. Finally, experimental verification was performed to assess the optical performance of the slanted gratings.

Adsorption of methyl orange and methylene blue on activated biocarbon derived from birchwood pellets

This study explored the adsorption capacity of a physically activated biocarbon derived from the pyrolysis of birchwood pellets (ABPB) towards two dyes - methyl orange (MO, anionic) and methylene blue (MB, cationic), at pH 2, 7 and 11. Compared to mineral commercial activated carbon (CACmineral), ABPB exhibited lower SSA, pores volume and surface; higher external surface and average pore diameter, similar ash content and aromaticity, and stronger hydrophilicity and polarity. The maximum adsorption capacity on ABPB was equal to 220 mg/g for MO and 91 mg/g for MB after 17 h. Batch tests with variable adsorbent amount (0.5–2.5 g/L) showed for both ABPB and CACmineral better results for lower adsorbent dose. Under all tested conditions, ABPB showed higher or analogous adsorption capacity compared to CACmineral. Based on the pKa of MB (3.80) and MO (3.46) and on the pHPZC of ABPB (5.3), the adsorption was favored at pH 2 for MO and at pH 11 for MB. Kinetics analysis and isotherm modelling revealed that, although many different physicochemical interactions occurred between ABPB and the dyes molecules, chemisorption is the rate-controlling step and prevalent mechanism. In conclusion, this study may provide support to further research aimed at exploring the effect of ABPB's physicochemical properties on the efficiency and mechanisms of dyes adsorption.

The effect of autoclave cycles on the mechanical properties and surface roughness of NiTi archwires: ex-vivo study

ObjectivesTo evaluate the effect of the universal and rapid autoclave cycles on the mechanical properties and surface roughness of nickel-titanium archwires following clinical use.Material and methodsThirty-six NiTi archwires (0.016 × 0.022 inch) were equally divided into a control group (Group A) and 2 experimental groups (Group B & C). Wires in group A were tested in the “as-received” form. Wires in the two other groups were installed in patients mouth for 4 weeks, and then autoclaved using the rapid-cycle (Group B) or the universal-cycle (Group C). All wires were subjected to 3-point bending test to calculate the elastic limit, modulus of elasticity, spring-back, yield strength, resilience and toughness. Atomic force microscopy (AFM) was used for surface roughness qualitative and quantitative analysis.ResultsGroup B showed significantly higher values of elastic limit, modulus of elasticity, resilience, yield strength and toughness than the other two groups. No significant differences were detected between groups A and C (P > 0.05). Group B showed significantly lower average surface roughness than the other two groups, but no significant differences were detected between groups A and C (P > 0.05).ConclusionsThe mechanical properties and surface roughness of clinically used NiTi wires were less affected by the universal-cycle than the rapid-cycle autoclaving. However, the difference between the effect of both autoclave cycles was diminutive.Clinical relevanceThe mechanical properties and surface roughness of the tested NiTi wires were not notably altered by clinical use and autoclaving.

Photocurable Thiol-Ene/Nanocellulose Elastomeric Composites for Bioinspired and Fluorine-Free Superhydrophobic Surfaces.

Artificially prepared superhydrophobic surfaces toward a self-cleaning "lotus effect" and anticontamination performance have become critically important in the past few years. However, most approaches to create the required topology with a hierarchical roughness comprise several manufacturing steps of varying practicality. Moreover, the desired low surface energy is in most cases achieved with fluorinated moieties that are currently criticized due to biological and environmental hazards. In this work, rapidly photocuring but weak thiol-ene resins were reinforced with cellulose nanofibrils (CNFs) to replicate lotus leaves via one-step UV nanoimprint lithography. The CNFs were surface-modified using countercation exchange of carboxyl groups and grafting of thiol and methacrylate functionalities. The formulation methodology resulted in free-flowing, shear-thinning composite resins without surfactants or dispersants. The rheological and photo-cross-linking behavior of the resins, the thermal stability, the mechanical performance, and the hydrophobicity of the cured composites were characterized. Notably, the surface modifications increased the as received fibril diameter (1.9 ± 0.6 nm) by 1.6-2.3 nm and raised the fibril-resin compatibility. The resins underwent rapid polymerization and the high thermal stability of thiol-enes was retained. The methacrylated nanofibrils (10 vol %) significantly strengthened the rubbery network, outperforming the neat thiol-ene polymer in terms of hardness (3.4×), reduced modulus (5.8×), and wear resistance (>100×). Moreover, the surface of lotus-texturized composites was superhydrophobic with a water contact angle of 155°, higher than that of the neat polymer (147°), and was self-cleaning. These CNF composite resins are compatible with fast-cure processes such as 3D printing and roll-to-roll processing, are exempt of fluorine or any other hydrophobization treatment, and are extremely wear-resistant.

A Novel BiOBr/CAU-17 Composite with Enhanced Photo-Catalytic Performance for Dye Degradation and Removal of Tetracycline Antibiotic Under Visible Light.

In order to improve the low specific surface area and high recombinant light generation carriers of BiOBr, loading BiOBr onto suitable Metal Organic Frameworks (MOFs) is an effective strategy to unleash its efficient visible light response and intrinsic catalytic activity. In this study, using classic MOF CAU-17 as a precursor, using a straightforward co-precipitation technique, four BiOBr/CAU-17 composites with distinct MOF contents values BCAU-1, BCAU-2, BC, AU-3, and BCAU-4 were created, and their photo-catalytic characteristics were examined. The BCAU-2 composite exhibited much higher photo-catalytic degradation efficiency for Rhodamine B (RhB) and Tetracycline (TC) than the pristine materials, counter compositions, and early reported materials. XRD, SEM, TEM, XPS, and EDX results revealed the strong synergistic photo-catalytic effect of BiOBr and CAU-17. The photocatalytic degradation of TC was significantly enhanced by the BiOBr bimetal modification, with the 2 wt.% BiOBr/CAU-17 nanocomposite achieving an 87.2 % degradation of TC and 82 % Total Organic Carbon (TOC) removal within 60 min. The high photo-degradation efficiency of BCAU-2 composite should be attributed to the efficient transfer of photo-generated carriers at interfaces and the synergistic effect between BiOBr/CAU-17. Furthermore, the experiments on the capture of the active species proved that the main active free radicals involved in the degradation of RhB and TC are attributed to the photo-induced holes h+ and ⋅ O2 - under visible light. The catalyst's efficacy is corroborated by the outcomes of photoluminescence spectroscopy and photo current response. This study offers a new understanding for the design of green synthesis schemes for photo-catalytic dye degradation and removal of certain antibiotics from the aquatic environment.

Gradient Hole Injection Inducing Efficient Exciton Recombination in Blue (475 nm) Perovskite QLEDs.

Perovskite quantum dots (QDs) are emerging as excellent light sources for light-emitting diodes (LEDs). However, the performance of blue perovskite QD-based LEDs (QLEDs) still lags behind that of red and green counterparts, which is hindered by blue perovskite QDs with broad bandgaps that tend to increase nonradiative recombination. Here, we designed a gradient energy for hole injection utilizing multiple hole injection layers (HTLs) combined with carbazole-based small-molecule modification to reduce the hole injection barrier between HTLs and QD layers and improve the hole injection efficiency, realizing efficient exciton recombination in blue perovskite QLEDs. Moreover, the QD film on the designed HTLs demonstrates a lower surface roughness and improved photoluminescence properties. The optimized blue CsPbCl3-xBrx QLEDs exhibit an impressive external quantum efficiency of 20.7% with an electroluminescence peak at 475 nm and a turn-on voltage of 2.6 V, representing the state-of-the-art for blue perovskite LEDs emitting in the range of 460-480 nm.

Novel Forming Shoulder for Coated Paper‐Based Materials With Improved Convertibility and Minimum Wrinkles for Use in Vertical Form, Fill and Seal Machines

ABSTRACTMost vertical form, fill and seal machines use thermoplastic films. However, the gradual shift towards sustainability has created challenges for the packaging industry to employ flexible coated paper‐based materials for packing products. Forming shoulders are a crucial component in packaging machinery for creating coated paper‐based packaging as the size and shape of the packaging depend on their geometrical features. However, the shoulder geometry and design can negatively affect paper packaging by causing unwanted wrinkles and tears, which can affect the shelf lives of products. Therefore, this study focused on developing a new shoulder and optimizing its geometrical parameters for coated paper‐based packaging. Conventional forming shoulders were experimentally investigated by evaluating the influence of their geometrical parameters on flexible coated papers before focusing on optimizing the new shoulder. Additionally, this study aimed to improve the overall runnability and convertibility of the coated paper on the forming shoulder. The newly designed optimized shoulder features an enhanced geometry that can minimize the stress–strain effect. Additionally, the computerized numerical control machined new shoulder features improved web tracking and material handling process. The study achieved to produce lower surface roughness with minimum number of wrinkles on the pillow bag's surface. Furthermore, it ensures that the oil‐ and grease‐resistance properties of the converted coated paper are maintained and feature an enhanced geometry that minimizes the stress–strain effect on paper, thereby offering a more sustainable and efficient packaging solution.

Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions

PTFE coatings were deposited on YT15 carbide substrates using spray technology. A series of examinations were conducted, including the use of surface and cross-section micrographs to analyze the structural integrity of the coatings. The surface roughness, the adhesion force between the PTFE coatings and the carbide substrate, and the micro-hardness of the coated carbide were also evaluated. Additionally, the friction and wear behaviors were assessed through dry sliding friction tests against WC/Co balls. The test results indicated that while the PTFE-coated carbide exhibited a rougher surface and reduced micro-hardness, it also demonstrated a significant reduction in surface friction and adhesive wear. These findings suggest that the PTFE coatings enhance the overall wear resistance of the carbides. The lower surface hardness and shear strength of the coatings influenced the friction performance, leading to specific wear failure mechanisms, such as abrasion wear, coating delamination, and flaking. Overall, the deposition of PTFE coatings on carbide substrates presents a promising strategy to enhance their friction and wear performance. This approach not only improves the durability of carbide materials but also offers potential applications in industries where reduced friction and wear are critical for performance.

Transparent, Flexible, Responsive Switching "Delayed" Amphiphilic Coatings Designed on the Basis of the Full-Cycle Antifouling Strategy.

Marine fouling on the surface of ships and equipment not only creates problems of enhanced resistance to navigation and increased energy consumption but also leads to unclear vision and inaccurate data collection. Antifouling coatings to resist fouling are effective, but it is difficult to achieve long-lasting fouling protection with a single interface state. Switching the status of the interface by intelligent response is a reasonable way to achieve full-cycle efficient antifouling. In this study, the hydrophobic and active antifouling interface in the initial state was achieved by adopting the fluorine-containing group and the natural extract (citronellol) as the antifouling active site. The switching of the interface relies on silanes, which respond to the generation of zwitterions in a seawater environment. Eventually, the interface switched from the hydrophobic state to the amphiphilic state with delayed formation, which achieved continued antifouling. Based on the full-cycle antifouling concept, the combination of low surface energy and antifouling active ingredients in the initial state sustainably switched surfaces in the midterm (free radicals generated during the hydrolysis process), and amphiphilic interfaces formed by "delays" produced an antifouling effect from the initial stage to the subsequent stage. The excellent antifouling activity (bacterial and diatom attachment inhibition by over 90% and significantly reduced mussel adhesion force), optical transparency, and flexibility of these coatings indicate the potential for the application of antifouling coatings prepared from hyperbranched silicone-based resins; they can also be used for data extraction sensors, underwater probes, marine photovoltaics, and other areas where transparency is required.

Tuning the Interfacial Deformation of Gliadin-Flaxseed Gum Complex Particles for Improving the Foam Stability

Gliadin nanoparticle (GNP) is a promising foaming agent, but its application is hindered by the limited foam stability under low acidic conditions. Herein, we attempted to tune the foam stability of GNP by coating it with flaxseed gum (FG) and investigated the structure, interfacial behaviors, and foam functionality of gliadin-FG (GFG) particles at pH 4.5. Results showed that the formation of GFG complex particles was driven by an electrostatic interaction between positive charge patches on the surface of GNP (~17 mV) and negative charges in FG molecule (~−13 mV) at all tested ratios. The addition of appropriate amounts of FG (1:0.05) effectively improved the foam stability of GNP. This was because GFG with larger sizes and lower surface charge possessed higher rigidity after coating with FG. When they adsorbed at the air/water interface, their deformation process was slower than that of GNP, as indicated by interfacial dilatational rheology and cryo-SEM, and the covered particles seemed to be more closely distributed to form solid-like and dense interfacial films. Notably, the addition of FG at a higher ratio (1:0.3) promoted the foam stability of GNP by about five folds because the larger GFG with suitable flexibility and wettability could form a stiff interface layer with more significant elastic response, and the unabsorbed particles and FG could form a gel-like network structure in the continuous phase. These characteristics effectively prevented foam disproportionation and coalescence, as well as retard the drainage. Our findings demonstrate that coating GNPs with FG is an effective approach to improve their application in foamed foods.

Facile Synthesis of Rhodium-Based Nanocrystals in a Metastable Phase and Evaluation of Their Thermal and Catalytic Properties.

Controlling the polymorphism of metal nanocrystals is a promising strategy for enhancing properties and discovering new phenomena. However, previous studies on Rh nanocrystals have focused on their thermodynamically stable face-centered-cubic (fcc) phase. Herein, a facile synthesis of Rh-based nanocrystals featuring the metastable hexagonal close-packed (hcp) phase is reported by using Ru seeds in their native hcp phase to template the deposition of Rh atoms. The success of such phase-controlled synthesis relies on the templating effect promoted by the small lattice mismatch between Ru and Rh and the slow dropwise titration of the precursor at an elevated temperature, ensuring the layer-by-layer growth mode and thus the formation of a conformal hcp-Rh shell. Faster injection rate of Rh(III) precursor leads to the formation of a rough Rh shell in the conventional fcc phase due to accelerated reaction kinetics. Considering both thermodynamic and kinetic aspects of this system, the hcp-Rh phase is favored when the low surface energy from smooth overlayers balances the high bulk energy of the metastable phase, achieved through tight control of reaction rates and deposition patterns. These Ruhcp@Rhhcp core-shell nanocrystals demonstrate thermal stability up to 400°C, while exhibiting higher catalytic activity toward ethanol oxidation reaction compared to Ruhcp@Rhfcc counterparts.

Effects of Spontaneous Curvature on Interfacial Adsorption and Collapse of Phospholipid Monolayers.

To function effectively, pulmonary surfactant must adsorb rapidly to the alveolar air/water interface, but avoid collapse from the interface when compressed to low surface tensions. Prior studies show that phospholipids in the cylindrical monolayers of the inverse hexagonal (HII) phase adsorb quickly. The monolayers have negative curvature, defined by the concave shape of the hydrophilic face. Formation of the HII structures, however, involves significant disruption of optimal chain-packing. Samples with significant spontaneous curvature, formed in the absence of applied force, may nonetheless have lamellar structures. The experiments here tested whether planar lamellar bilayers formed by phospholipids with negative spontaneous curvature might adsorb rapidly but collapse slowly. Prior studies have shown that binary mixtures of dioleoyl phosphatidylcholine-dioleoyl phosphatidylethanolamine (DOPC-DOPE) with higher mol fractions of DOPE (XPE) have more negative spontaneous curvature. Samples with higher XPE adsorbed more rapidly but also collapsed more quickly. Over that range of XPE, small angle X-ray scattering showed only lamellar structures. The HII phase was undetectable. The results suggest that the innate tendency of the phospholipids to form curved structures has primary importance for adsorption rather than the presence of HII structures. Planar structures are insufficient to minimize the tendency of spontaneous curvature to promote collapse. These findings are consistent with adsorption and collapse that occur via rate-limiting structures with significant negative curvature.

Durable Superhydrophobic Coatings with Attapulgite for Inhibiting 5G Radome Rain Attenuation.

5G radomes are easily wetted and stained by rainfall, which greatly reduces the quality of signal transmission. Superhydrophobic coatings are expected to solve this problem because of their unique wettability, but it is still challenging to develop robust superhydrophobic coatings via simple methods. Here, we report the design of robust superhydrophobic coatings containing oxalic acid-modified attapulgite (MDP) for inhibiting rain attenuation of 5G radomes. First, a homogeneous suspension was prepared by nonsolvent-induced phase separation of a silicone-modified polyester adhesive (SMPA) solution containing fluorinated MDP (F-MDP) nanorods. Superhydrophobic coatings can be easily prepared by spraying the suspension. The effects of phase separation and the SMPA/F-MDP ratio on the surface morphology, superhydrophobicity, and stability of the coatings were systematically investigated. The micro-/nanostructure and low surface energy endow the coatings with excellent static and dynamic superhydrophobicity. Compared with previous studies, the coatings exhibit excellent mechanical stability, flexibility, chemical stability, and pressure resistance due to the combined effects of adhesion by SMPA, self-similar micro-/nanostructures, reinforcement by the MDP nanorods, etc. Consequently, the coatings show good performance in preventing rain attenuation of 5G radomes, an emerging application of Superhydrophobic coatings. We believe that the coatings have great application potential in various fields, including 5G communication.

CO2-selective membrane reactor process for water-gas-shift reaction with CO2 capture in a coal-based IGCC power plant

Integrated gasification combined cycle (IGCC) power plants enable pre-combustion carbon capture to reduce CO2 emissions. Membrane water-gas-shift (WGS) reactors can intensify these processes by converting raw syngas to H2 with simultaneous CO2 capture in one unit. This paper reports process design and techno-economic analysis (TEA) for a membrane reactor (MR) process with a CO2 selective ceramic-carbonate dual-phase (CCDP) membrane for WGS reaction with CO2 capture for a IGCC power plant. The target performance includes CO conversion > 95 %, hydrogen purity > 90 %, CO2 purity > 95 %, and carbon capture > 90 %. Using a commercial catalyst and a CCDP membrane, the MR can achieve the performance target at 750 °C and space velocity of 250 h−1. The outcome of the process design and TEA shows that the CCDP MR has an operating cost of $24 M/year, significantly lower than that for the conventional processes (40 M$/year). However, the MR process has a higher capital cost ($1007 M) than the conventional process ($527 M) because of the higher cost of the CCDP MRs. Modeling analysis shows a MR with higher CO2 permeance can deliver the target at a higher space velocity and lower membrane surface area to catalyst volume ratio, leading to a significantly reduced MR capital costs.

The Application of TiO2/ZrO2-Modified Nanocomposite PES Membrane for Improved Permeability of Textile Dye in Water.

This study investigates the modification of polyethersulfone (PES) membranes with 1 wt% titanium dioxide (TiO2), zirconium dioxide (ZrO2) and a nanocomposite of TiO2/ZrO2. The aim was to efficiently remove Rhodamine B (RhB) from water using a threefold approach of adsorption, filtration and photodegradation. Among the modified membranes (TiO2, ZrO2 and TiO2/ZrO2), the TiO2/ZrO2-PES nanocomposite membrane showed a better performance in rejection of RhB than other membranes with the rejection efficiency of 96.5%. The TiO2/ZrO2-PES membrane was found to possess a thicker selective layer and reduced mean pore radius, which contributed to its improved rejection. The TiO2/ZrO2 nanocomposite membrane also showed high bulk porosity and a slightly lower contact angle of 69.88° compared to pristine PES with a value of 73°, indicating an improvement in hydrophilicity. Additionally, the TiO2/ZrO2-PES nanocomposite membrane demonstrated a relatively lower surface roughness (Sa) of 8.53 nm, which offers the membrane antifouling properties. The TiO2/ZrO2-PES membrane showed flux recovery ratio (FRR), total fouling (Rt), reversible fouling (Rr) and irreversible fouling (Rir) of 48.0%, 88.7%, 36,8% and 52.9%, respectively. For the photocatalytic degradation performance, the removal efficiency of RhB followed this order TiO2 > TiO2/ZrO2 > ZrO2 (87.6%, 85.7%, 67.8%). The tensile strength and elongation were found to be compromised with the addition of nanoparticles and nanocomposites. This indicates the necessity to further modify and optimise membrane fabrication to achieve improved mechanical strength of the membranes. At low pressure, the overall findings suggest that the TiO2/ZrO2 nanocomposite has the potential to offer significant improvements in membrane performance (water flux) compared to other modifications.

Flow boiling heat transfer in multi-stage enhanced open microchannels with micro/nano structures

In the realm of flow boiling research, open microchannels heat sink is garnering more attention due to its potential in enhancing heat transfer and mitigating flow instability. Nevertheless, growing heat dissipation needs necessitate further enhancement of the heat removing capability of flow boiling within open microchannels. In this paper, experimental research on flow boiling in open microchannels utilized a new environmentally friendly refrigerant SF-33 and presented a novel heat transfer enhancement strategy, specifically, a multi-region enhancement strategy for diverse flow pattern stages. A copper heat sink with 25 open microchannels was fabricated, and a layer of copper powder particles was sintered on the channel bottom to create a microporous structured surface in about 1/3 of the inlet region. Several layers of copper wire mesh with micropores were sintered in about 1/3 of the outlet region, and the nanostructures were grown on the wire mesh by chemical treatment, resulting in a micro-nanocomposite structure. The final product formed the multi-stage enhanced open microchannels (MSEOM). The heat transfer performance and pressure drop of SF-33 saturated flow boiling in MSEOM under different operating conditions were determined, and the transitions of flow patterns were visualized to analyze the mechanism of two-phase heat transfer. The study demonstrated that despite SF-33 having a low latent heat of vaporization, its flow boiling heat transfer coefficient in MSEOM was high. This was attributed to the enhanced effect of multi-region surface modifications on heat transfer. Additionally, a vapor plug breakup-dispersed bubble flow pattern was observed for the first time, which resulted from the combined influence of the low surface tension property of SF-33 and the boosted nucleate boiling triggered by the micro-nanostructures in the outlet region.

Hydrolysis of phospholipid monolayers by phospholipase A2 revealed by heterodyne-detected sum frequency generation (HD-SFG) spectroscopy.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 acyl ester linkage in phospholipid, producing lysophospholipid and fatty acid in the presence of Ca2+. The hydrolysis mediated by PLA2 has attracted much interest in various fields, such as pharmacy and biotechnology. It is recognized that PLA2 cannot hydrolyze phospholipid monolayers at high surface coverage. However, the origin of different PLA2 activities is not fully understood yet. The present study investigated the interaction between DPPC (16:0 PC) monolayer and PLA2 using heterodyne-detected sum frequency generation spectroscopy, which is interface-specific spectroscopy and highly sensitive to molecular symmetry based on a second-order nonlinear optical process. It was revealed that PLA2 adsorbs to the DPPC monolayer on the aqueous solution surface only when the surface coverage is low. The adsorption at the low surface coverage significantly changes the interfacial structures of PLA2 and the hydration, which are stabilized by the presence of Ca2+. Therefore, the restriction of the hydrolysis of phospholipid monolayers at high surface coverage can be rationalized by the inhabitation of the PLA2 adsorption. The present study deepens our molecular-level understanding of the hydrolysis of phospholipids by PLA2.

Hierarchical Bifunctional NiO Electrocatalyst: Highly Porous Structure Boosting the Water Splitting Activity.

The development of an efficient, low-cost and earth-abundant electrocatalyst for water splitting is crucial for the production of sustainable hydrogen energy. However their practical applications are largely restricted by their limited synthesis methods, large overpotential and low surface area. Hierarchical materials with a highly porous three-dimensional nanostructure have garnered significant attention due to their exceptional electrocatalytic properties. These hierarchical porous frameworks enable the fast electron transfer, rapid mass transport, and high density of unsaturated metal sites and maximize product selectivity. Here the process involved obtaining monodispersed microrod-shaped Ni(OH)2 through a hydrothermal reaction, followed by a heat treatment to convert it into hierarchical microrod-shaped NiO materials. N2 sorption analysis revealed that the BET surface area increased from 9 to 89 m2/g as a result of the heat treatment. The hierarchical microrod-shaped NiO materials demonstrated outstanding bifunctional electrocatalytic water splitting capabilities, excelling in both HER and OER in basic solution. Overpotential of 347 mV is achieved at 10 mA/cm2 for OER activity, with a Tafel slope of 77 mV/dec. Similarly, overpotential of 488 mV is achieved at 10 mA/cm2 for HER activity, with a Tafel slope of 62 mV/dec.

Electrospun Pt-TiO2 nanofibers Doped with HPA for Catalytic Hydrodeoxygenation

Electrospinning is utilized to fabricate catalytic nanofiber scaffold for biocrude upgrading in hydrodeoxygenation (HDO) following computational studies suggesting the need for nano-catalysts for efficient HDO conversion and selectivity. Here, Pt-TiO2 nanofibers are fabricated through electrospinning, followed by wet impregnation with a heteropoly acid (HPA), tungstosilicic acid. Intensive heat treatments were incorporated during and after processes to obtain a HPA doped Pt-TiO2 nano-catalyst. Catalytic HDO was performed in a batch reactor with phenol as the raw biocrude dissolved in hexadecane. The HPA doped Pt-TiO2 catalyst demonstrated promising HDO performance of 37.2% conversion and a 78.9% selectivity to oxygen free benzene and the remainder 21.1% as diphenyl ester as a result of esterification by acidic components of the catalyst. Additionally, BET surface area characterization show a low surface area 16.9 m2 g−1 significantly lower than existing commercial catalysts and a mesoporous nature suitable for selectivity. The presence of HPA on the anatase nanofiber compensated for low platinum nanoparticles crystallinity on the nanofibers. This work might create needed alternatives for preparing HDO catalysts for efficient aromatics production.

Investigation on load - transfer characteristics of spherical hinge structure of swivel bridge based on scale distortion model

The mechanical properties of the swivel spherical hinge, a critical component in swivel bridge structures, remain inadequately understood. This study precisely examines the load-transfer characteristics of the swivel spherical hinge using a combination of finite element simulation and scaled model loading tests. An optimized hinge model, accounting for distortion effects and strategic placement of measurement points, was constructed and tested in the laboratory. Results indicate that the scaled model exhibited consistent elastic deformation, ensuring structural integrity and stability. The results indicate that under a 122 kN load, the average discrepancy between the experimental data and numerical predictions was only 1.53 %, highlighting the numerical model's accuracy and reliability. Additionally, the center of the slider experienced a compressive stress of approximately 2.7 MPa, while the edge endured 5.3 MPa, reflecting a non-uniform load distribution. Stress concentrations at the slider's projection were 2–5 times greater than at other measurement points on the steel-concrete interface of the hinges. The lower spherical hinge surface displayed a complex stress pattern combining tensile and compressive stresses, resulting from slider compression and hinge surface expansion. This research provides valuable insights into the load-transfer mechanisms of swivel spherical hinges, offering guidance for the design and construction of swivel bridges.