Original Substrate Research Articles

Constructing a monolithic amino-functionalized poly(ether sulfone) loose nanofiltration membrane for efficient dye/salt fractionation

Loose nanofiltration (LNF) is a promising new technique for dye/salt separation, but LNF membranes still suffer from low permeance and inadequate selectivity. In this study, novel monolithic amino-functionalized poly(ether sulfone) (PES) LNF membranes were developed in three steps, PES powder-grafted with polyacrylonitrile (PAN) under gamma-ray irradiation and membrane preparation via non-solvent-induced phase separation, followed by an amination process. The resultant aminated PES LNF membrane with tetraethylenepentamine (APES-TP) had a thinner skin layer and unusual irregular vesicle-like pore structure in its sublayer compared with the original PES substrate. The amination process increased the hydrophilicity of the APES-TP membranes and partially neutralized the surface zeta-potential. The permeation test confirmed that the APES-TP membrane exhibited 100 % NaCl permeation together with high levels of pure water permeance (77.9 L m–2h−1 bar−1) and dye rejection (98.5 % for Congo red, 97.1 % for Nair blue, and 97.6 % for methyl blue). Even when paired with simulated industrial wastewater containing multiple direct dyes and inorganic salts (1 g L–1 dye and 5 g L–1 salts), the APES-TP membrane still rejected 99.4 % of the mixed dyes, proving its practical applicability to treating industrial dye wastewater. Furthermore, the APES-TP membrane exhibited excellent endurance to harsh conditions (such as acidic, alkaline, and oxidative) and exceptional recyclability (97.9 % permeance recovery rate). This study bridges the gap between conventional nonsolvent phase inversion and the emerging LNF membrane fabrication technology, allowing the LNF technique to be used to fractionate organic matters with salts in batch mode.

Direct Growth of Wafer-Scale Self-Separated GaN on Reusable 2D Material Substrates.

Free-standing gallium nitride has been prepared using various methods; however, the removal of the original substrate is still challenging with low success rates. In this work, 2-inch free-standing GaN films are obtained by direct growth on a fluoro phlogopite mica by hydride vapor-phase epitaxy. Depending on the van der Waals (vdW) interaction between GaN and mica, the effect of the significant lattice mismatch is effectively reduced; thus, enabling the production of a high-quality wafer-scale GaN film on mica. The vdW-induced cracks at GaN-mica interface are found to be initiated near the interface so that GaN can easily separate from mica during rapid cooling. Owing to the hydrophilic nature of mica, the residual GaN on the mica can be lifted off by following deionized water treatment, and the mica substrate can be repeatedly used to grow free-standing GaN films. The self-separated GaN films grown on both pristine and used mica substrates are single crystallinity and strain-free. Additionally, a fully functional ultraviolet light-emitting diode is demonstrated to show that the self-separated GaN films are of device quality. The proposed approach achieves epitaxial growth of wafer-scale single-crystalline GaN on 2D materials and provides a new substrate option in the technology of III-V materials.

Recycling and reusing ITO substrates from perovskite solar cells: A sustainable perspective

In the present work we have carried out two benign routes to recycle ITO coated glass substrates of perovskite solar cells (PSCs) using diluted potassium hydroxide (KOH) or citric acid solutions. After removal of the different layers of the cells structural, optical and electrical properties of ITO recycled substrates were characterized and compared with virgin ones. Sheet resistance and roughness measurements indicate that diluted KOH treatment is the preferred method as it leads to no detectable damage to the ITO coating. We also evaluate the factor of merit of ITO substrate taking into account transmittance and conductivity results obtaining similar values for KOH ITO recovered and original substrates. A new PSC device (with a wide bandgap perovskite absorber) using this recycled ITO was manufactured with identical power conversion efficiencies to the ones achieved with pristine substrates, in this case approx. 18 %.

Biomimetic Leaf-Shaped Wedge Structure with Mixed Wettability for Fog Harvesting.

Water scarcity is a pressing issue in arid and semi-arid regions, making fog harvesting a promising method for water collection. However, enhancing the rate of fog harvesting remains a challenge. Controlling the movement of droplets on functional surfaces is crucial for the development of effective water-harvesting devices. In this study, a three-dimensional (3D) fog-harvesting device with mixed wettability is fabricated using a combination of physical and chemical techniques. With inspiration drawn from natural organisms, such as the desert beetle and Nephrolepis cordifolia, which can both live in low humidity, a copper substrate with a leaf-shaped wedge superhydrophilic structure and flat superhydrophobic regions is fabricated for fog harvesting. The modified surface results in a maximum 49.89% improvement in fog-harvesting efficiency compared to the original copper substrate. The synergistic effect of the 3D structure and mixed wettability of this study offers an idea for improving fog collection efficiency, with potential implications for energy sustainability water resources.

Capillary Force-Induced Graphene Spontaneous Transfer and Encapsulation of Silver Nanowires for Highly-Stable Transparent Electrodes.

Silver nanowires (NWs) (AgNWs) have emerged as the most promising conductive materials in flexible optoelectronic devices owing to their excellent photoelectric properties and mechanical flexibility. It is widely acknowledged that the practical application of AgNW networks faces challenges, such as high surface roughness, poor substrate adhesion, and limited stability. Encapsulating AgNW networks with graphene has been recognized as a viable strategy to tackle these issues. However, conventional methods like self-assembly reduction-oxidation or chemical vapor deposition often yield graphene protective layers with inherent defects. Here, we propose a novel one-step hot-pressing method containing ethanol solution that combines the spontaneous transfer and encapsulation process of rGO films onto the surface of the AgNWs network, enabling the preparation of flexible rGO/AgNWs/PET (reduced graphene oxide/silver NWs/polyethylene terephthalate) electrodes. The composite electrode exhibits outstanding photoelectric properties (T ≈ 88%, R ≈ 6 Ω sq-1) and possesses a smooth surface, primarily attributed to the capillary force generated by ethanol evaporation, ensuring the integrity of the rGO delamination process on the original substrate. The capillary force simultaneously promotes the tight encapsulation of rGO and AgNWs, as well as the welding of the AgNWs junction, thereby enhancing the mechanical stability (20,000 bending cycles and 100 cycles of taping tests), thermal stability (∼30 °C and ∼25% humidity for 150 days), and environmental adaptability (100 days of chemical attack) of the electrode. The electrode's practical feasibility has been validated by its exceptional flexibility and cycle stability (95 and 98% retention after 5000 bending cycles and 12,000 s long-term cycles) in flexible electrochromic devices.

DFT insights into the TM(Cu, Ni, Ag) and TMO(CuO, NiO, Ag2O) modified HfSe2 for detecting PD fault gases

Partial Discharge (PD) in oil-immersed transformers threatens the safe and stable operation of the transformer. PD causes the transformer oil to decompose and produce fault gas. Therefore, the operating status of the transformer can be evaluated through the detection of characteristic fault gas. Through simulation research, this paper proposes to use HfSe2 substrate modified with metal single atoms (Cu, Ni and Ag) and their oxides (CuO, NiO and Ag2O) to detect decomposed fault gases (CO, C2H2, CH4) in transformer oil. DFT was used to systematically study the adsorption of the target gas on the surface of the original substrate and the modified substrate. The research results show that the conductivity of the doped HfSe2 substrate increases to a certain extent, and the band gap also drops from the undoped 0.563 eV to 0.108–0.554 eV. By analyzing the adsorption parameters, it was found that the adsorption capacity of metal single atoms (Cu, Ni and Ag) is lower than metal oxides (CuO, NiO and Ag2O). Among the six substrates, the adsorption capacity of the target gases is ranked as CO > C2H2 > CH4, in which CO and C2H2 are chemically adsorbed, while CH4 is physically adsorbed. In terms of sensing performance, it was found through recovery time and sensitivity analysis that NiO-HfSe2 and Ag2O-HfSe2 can be used to selectively detect C2H2. The research results can provide a theoretical basis for the application of HfSe2 in oil-immersed transformer operating status detection and gas-sensitive sensor detection.

Superhydrophobic Surfaces Prepared from Columnar Units by Convenient Electrodeposition with Excellent Mechanical Stability Impact and Corrosion Resistance.

Regular array structures prepared by laser processing and three-dimensional printing have promising applications in building stable superhydrophobic structures. However, the size of the materials processed by these two methods is affected by the size of the processing equipment, which prevents the processing of large-size materials. In this paper, a columnar unit consisting of a spherical structure with similar mechanical stability to the array structure is designed and prepared for metal surface protection. A convenient electrodeposition method was used to deposit a layer of columnar micron-sized copper consisting of spheres on the surface of a 6061 aluminum alloy. Subsequently, modified ZrO2 nanoparticles and polytetrafluoroethylene (PTFE) were sprayed on the surface to form a superhydrophobic surface with synergistic columnar units and ZrO2 (CAZ). The structure was tested and found to have excellent mechanical stability, maintaining the superhydrophobic properties of the surface even after 200 abrasion cycles of 1000-grit sandpaper under a 500 g load. Moreover, the vertical deformation of the CAZ sample under normal pressure was increased by a factor of 4 compared to the original substrate. Importantly, in subsequent corrosion resistance tests, the CAZ samples showed a two-order-of-magnitude improvement in self-corrosion current density and impedance modulus at low frequencies compared to the original substrate. This strategy is an effective method for preparing mechanically stable superhydrophobic structures that are low-cost and large enough to provide long-term protection for metal surfaces. It is particularly suitable for surface protection of instruments and automotive chassis armor.

Fitness landscape of substrate-adaptive mutations in evolved amino acid-polyamine-organocation transporters.

The emergence of new protein functions is crucial for the evolution of organisms. This process has been extensively researched for soluble enzymes, but it is largely unexplored for membrane transporters, even though the ability to acquire new nutrients from a changing environment requires evolvability of transport functions. Here, we demonstrate the importance of environmental pressure in obtaining a new activity or altering a promiscuous activity in members of the amino acid-polyamine-organocation (APC)-type yeast amino acid transporters family. We identify APC members that have broader substrate spectra than previously described. Using in vivo experimental evolution, we evolve two of these transporter genes, AGP1 and PUT4, toward new substrate specificities. Single mutations on these transporters are found to be sufficient for expanding the substrate range of the proteins, while retaining the capacity to transport all original substrates. Nonetheless, each adaptive mutation comes with a distinct effect on the fitness for each of the original substrates, illustrating a trade-off between the ancestral and evolved functions. Collectively, our findings reveal how substrate-adaptive mutations in membrane transporters contribute to fitness and provide insights into how organisms can use transporter evolution to explore new ecological niches.

Microplastic-free, single-layered functional surface with localized liquid-discharging molecular channels for disposable hygiene products

Conventional disposable absorbent hygiene products (DAHPs) currently represent a significant type of solid waste in landfills and are a substantial producer of fiber-based microplastics. In this work, a novel multifunctional cellulose nonwoven (CNW) is reported. The key structural design of this material was achieved by covalently grafting a naturally cycloheptatriene product namely hinokitiol and a silane covalent bridge, successfully transforming the original super hydrophilic substrate into a single-layered, multifunctional material with precisely designed liquid-discharging molecular channels and a tailored, sophisticated hydrophobic/hydrophilic distribution structure. This 3D structure perfectly mimics the conventional adhesive-bonded polyolefin/polyesters laminates comprising a top sheet and a liquid acquisition and distribution layer (ADL). The results of XPS and 1H NMR indicated the hinokitiol was successfully chemically bonded to the CNW surface. Compared with polyolefin or cotton substrates, the optimal CNW product (CNW-H-A-2) exhibits significantly improved long-term wearing comfort by minimizing the liquid strike-through time (by 26–27%), reducing wet-back amount (by 65–90%), and ensuring an outstanding air-permeability (3011 mm·s-1). Excellent antibacterial properties against Staphylococcus aureus (86.4%) and Escherichia coli (97.3%) were achieved due to the good preservation of the bioactive phenol groups of hinokitiol. Additionally, it can be completely enzymatically-degraded within 24 h. This strategy holds promise as a potential solution for mitigating fiber-based microplastics pollution of DAHPs.

Adsorption of dissolved gases on the TM (Pt, Pd) doped XP(X=In, Ga): A DFT study

Using 2D materials to detect dissolved gases in transformer oil can effectively evaluate the operating status of power systems. In this study, the Pt and Pd atoms are used to modify InP and GaP monolayers for detecting the target gases (C2H2, C2H4, CH4). The band gaps of modified structures are reduced and became more compact compared to the original substrates. The adsorption characteristics of the target gases on the modified substrates are systematically analyzed through adsorption parameters, DCD and DOS. The adsorption effect of the modified InP monolayers on the target gases is ranked as: C2H2>C2H4>CH4. The adsorption capacity of the modified GaP monolayers to the target gases is: C2H4>C2H2>CH4, however the adsorption capacity of the Pd-GaP/gases system is consistent with that of the modified InP monolayers. The sensitivity and recovery time of every gas adsorption systems are further analyzed. In addition, this study provides a theoretical direction for exploring the application prospects of InP and GaP monolayers in the evaluation of operating conditions of oil-immersed transformers.

Enhancement of Filtration Performance Characteristic of Glass Fiber-Based Filter Media, Part 2: Chemical Modification with Surface-Active Treatment.

Standard glass fiber filter media were chemically modified with suitably chosen surface-active agents. The aim of these modifications was to improve the three fundamental filtration performance characteristics, namely, to increase the separation efficiency, reduce the differential pressure (∆P) and increase the dirt holding capacity (DHC). The increase in separation efficiency was considered quantitatively in terms of changes in the work of adhesion between the contaminant and the modified media substrate derived from the contact angle measurements. The experimental confirmation of this behavior was demonstrated by an improved separation efficiency especially for particles in the smaller size ranges, well below the mean porosity of the original substrate. In addition, the effect of different surface modifications, especially those of the opposite ends of the surface energy values, has clearly manifested itself in the experimental results of separation efficiency derived from the multipass evaluations. Collectively, the obtained contact angle (surface energy) and separation efficiency results are strongly indicative of a wide range of filtration performance enhancements that can be achieved through suitably chosen surface-active modification of standard substrate materials.

Recover the tensile strength of hard aluminum alloy through laser assisted cold spray

In the present study, Al6061/Al2O3 composite coating was produced to repair the notched Al7075 substrate by cold spraying (CS) and laser assisted cold spray (LACS) technology. The preparation process and parameter selection of high-performance coating were discussed by combining simulation and experiment. Results showed that the LACS experiment guided by simulation results achieved high-quality bonding of single particle with the substrate. In addition, the tensile strength of samples repaired by LACS recovered to the level of original substrate, and the ductility was significantly higher than that of CS process. This is attributed to the introduction of laser irradiation heating, which improves the plastic deformation ability of particles and produces atomic-level metallurgical bonding between the particles. This study provides a possibility for the repair and remanufacture research of high-quality components, and has great development potential in future research.

Nutritive value of feed substrate waste from black soldier fly larvae production, and its potential as an aquafeed ingredient

Abstract Black soldier fly larvae (BSFL, Hermetia illucens) are an alternative source of protein whereas little research has yet been conducted to investigate the potential application of feed substrate waste (FSW) from larval production in aquaculture. The nutritive value and physicochemical properties of FSW from BSFL were here investigated in vitro. Ten-day-old first-instar larvae were cultivated on two feed substrates: laying hen feed (FS I) or a laying hen feed-rice bran blend (1:1 w/w, FS II). FSW samples were collected at day 4.5 (0.5FSW) and day 9 (1FSW) of larval rearing, and compared to the original feed substrate (0FSW). Crude protein increased depending on FS type, harvesting time (HT), and their interaction. Crude lipid, crude fiber, acid detergent fiber, neutral detergent fiber, crude ash, nitrogen-free extract, and gross energy decreased (). Analysis of the physicochemical properties of FSW by various techniques (scanning electron microscopy, differential scanning colorimetry, X-ray diffractometry, and Fourier transform infrared spectroscopy) revealed qualitative and quantitative changes in FSW, driven by biological processes of BSFL. The digestibility of protein in FSW was determined by an in vitro protein digestibility (IVPD) test using crude digestive enzyme extracts from Nile tilapia (Oreochromis niloticus) and striped catfish (Pangasianodon hypophthalmus). 1FSW from FS I showed significantly better availability of protein relative to 0.5FSW (), while the IVPD of FSW from FS II was stable () or reduced (). Findings from this study suggest FSW from BSFL cultivation could be a protein source in aquafeed.

High-reflectivity composite metal substrate for high-power IRLED

Substrate transfer technology is a common way to prepare high-power infrared light emitting diode (IRLED), which seriously affects the photoelectric performance and reliability of LED. In this paper, a preparation technology of LED with composite metal substrate is presented. Based on electroplating and electron beam evaporation, AuGeNi/Au(1)/Au(2)/Cu composite metal substrate with thickness of 70 nm/30 nm/100 nm/45 μm was prepared, and low resistivity of 4.65 × 10−6 Ω⋅cm2 and high reflectance of 91.3 % were obtained. Compared with the original GaAs substrate, the light output power (LOP) of electroluminescence is increased by 89.2 % at the current of 300 mA.

Elucidating the Role of O2 Uncoupling for the Adaptation of Bacterial Biodegradation Reactions Catalyzed by Rieske Oxygenases.

Oxygenation of aromatic and aliphatic hydrocarbons by Rieske oxygenases is the initial step of various biodegradation pathways for environmental organic contaminants. Microorganisms carrying Rieske oxygenases are able to quickly adapt their substrate spectra to alternative carbon and energy sources that are structurally related to the original target substrate, yet the molecular events responsible for this rapid adaptation are not well understood. Here, we evaluated the hypothesis that reactive oxygen species (ROS) generated by unproductive activation of O2, the so-called O2 uncoupling, in the presence of the alternative substrate exert a selective pressure on the bacterium for increasing the oxygenation efficiency of Rieske oxygenases. To that end, we studied wild-type 2-nitrotoluene dioxygenase from Acidovorax sp. strain JS42 and five enzyme variants that have evolved from adaptive laboratory evolution experiments with 3- and 4-nitrotoluene as alternative growth substrates. The enzyme variants showed a substantially increased oxygenation efficiency toward the new target substrates concomitant with a reduction of ROS production, while mechanisms and kinetics of enzymatic O2 activation remained unchanged. Structural analyses and docking studies suggest that amino acid substitutions in enzyme variants occurred at residues lining both substrate and O2 transport tunnels, enabling tighter binding of the target substrates in the active site. Increased oxygenation efficiencies measured in vitro for the various enzyme (variant)-substrate combinations correlated linearly with in vivo changes in growth rates for evolved Acidovorax strains expressing the variants. Our data suggest that the selective pressure from oxidative stress toward more efficient oxygenation by Rieske oxygenases was most notable when O2 uncoupling exceeded 60%.

Parametric optimization and minimization of corrosion rate of electroless Ni–P coating using Box-Behnken design and Artificial Neural Network

In this study, parametric optimization has been conducted to determine the optimal combination of parameters, considering the corrosion rate of an electroless Ni–P coating onto a copper substrate as a response, and a predictive model has been prepared using Artificial Neural Network (ANN). The concentration of nickel sulphate, sodium hypophosphite, and bath temperature—the three design factors—have been considered as the process parameters. 20 g/L of nickel sulphate, 20 g/L of sodium hypophosphite, and a bath temperature of 85 °C have been found to be the optimum conditions using the Box-Behnken Design (BBD) of the experiment for the deposition of Ni–P coating. The corrosion rate of the as-deposited coat-ed sample in the optimum condition is 1.06μm/Y, which is almost half of that of the original copper substrate. Further, an analysis of variance (ANOVA) has been performed in order to visualize and investigate the impact of the process parameters. A predictive model, the Artificial Neural Network, is employed, and ANN 3-10-1 is found to be the best fit model to predict the corrosion rate of Ni–P, where 3 indicates 3 input variables, 10 indicates 10 hidden neurons, and 1 indicates 1 output. The surface morphology of an electroless Ni–P-coated copper substrate has been studied using a scanning electron microscope (SEM), while the elemental study has been carried out using energy dispersive X-ray analysis (EDX).

Galf-Specific Neolectins: Towards Promising Diagnostic Tools.

In the absence of naturally available galactofuranose-specific lectin, we report herein the bioengineering of GalfNeoLect, from the first cloned wild-type galactofuranosidase (Streptomyces sp. strain JHA19), which recognises and binds a single monosaccharide that is only related to nonmammalian species, usually pathogenic microorganisms. We kinetically characterised the GalfNeoLect to confirm attenuation of hydrolytic activity and used competitive inhibition assay, with close structural analogues of Galf, to show that it conserved interaction with its original substrate. We synthetised the bovine serum albumin-based neoglycoprotein (GalfNGP), carrying the multivalent Galf units, as a suitable ligand and high-avidity system for the recognition of GalfNeoLect which we successfully tested directly with the galactomannan spores of Aspergillus brasiliensis (ATCC 16404). Altogether, our results indicate that GalfNeoLect has the necessary versatility and plasticity to be used in both research and diagnostic lectin-based applications.

Solid-like slippery surface for anti-icing and efficient fog collection

Ice accumulation on the surface of aerospace and transportation equipment under extreme weather seriously endangers the safety and efficiency of equipment operation. In recent years, metal corrosion, especially in the marine engineering industry, has become a global concern. The slippery liquid infused porous surface (SLIPS) is a new bionic surface which has caused extensive research in recent years, and has great potential in anti-corrosion and anti-icing. In this study, a multifunctional solid-like lubricated slippery surface (SL-SLIPS) was developed by superhydrophobic modification of the base of copper hydroxide nanoneedles and injection of solid-like lubricant synthesized by embedding oil-stored mesoporous silica nanoparticles on the surface of epoxy resin. At −30 °C, the delayed icing time on the surface of the SL-SLIPS sample was 22.6 times that of the original copper substrate. The ice adhesion was tested on the surface of the sample, and the results showed that the adhesion of the icicle on the SL-SLIPS surface was the smallest, which decreased by 89% compared with the original copper substrate. In addition, SL-SLIPS have excellent corrosion resistance and rapid droplet trapping, nucleation and drop. It has good practical application prospects in corrosion resistance of marine equipment and icing resistance of aerospace and transportation equipment. This study provides new ideas for the design of new slippery surfaces and their application in practical fields, such as anti-corrosion of offshore equipment, anti-icing of equipment in aviation and fog collection engineering in industry.

Transition-metal-doped Hf2CO2 as a promising sensor for methane: a DFT study

Density functional theory (DFT) methods were used to study the atomic and electronic structures of methane molecules adsorbed on pristine, vacancy-defective, and transition-metal (TMs: Mn, Fe, Y, Mo, Ta, W)-doped Hf2CO2. The interaction distance between the methane molecules and original substrate was large, and the adsorption energy was small, suggesting that the a physisorption adsorption. After introducing O-vacancy, the adsorption of CH4 changed into chemisorption. Through the doping with TM dopants, the methane molecule adsorbed onto the Ta-doped Hf2CO2 exhibited the highest stability and the largest adsorption energy. In addition, the W-doped Hf2CO2 changed from being a semiconductor to being a conductor after the adsorption of methane molecules onto the material; this phenomenon suggests that the change can be used as a signal for sensors in detecting methane gas. These results are expected to provide new insights into the design of gas sensors based on MXenes materials.

Transition metals doped Zr2CF2 as promising sensor and adsorbent for NH3

The effective adsorption and treatment of toxic gases have attracted great attention amongst researchers, particularly the use of new two-dimensional materials for achieving the adsorption of toxic gases. We applied the density functional theory to investigate the stability, geometric structural, electrical, and magnetic properties of NH3 molecules adsorbed on pristine, F-vacancy defected, and transition-metals (V, Cr, Mn, Y, Nb, and Mo) doped Zr2CF2. The charge transfer and adsorption energy of the original substrate were low, indicating that the interaction between NH3 and Zr2CF2 was primarily physical adsorption. After introducing F-vacancy and TM-doping, the adsorption stability was enhanced, with the large charge transfer and high adsorption energies indicating that the adsorption of NH3 transitioned to chemisorption. Electronic density of state diagrams suggested that the enhanced interaction was mainly caused by the hybridization of the d orbitals of dopants and p orbitals of the adsorbed NH3 molecules. The adsorption energy of NH3 molecules on Y-doped Zr2CF2 was the highest at a value of −1.425eV, and the material was also explored as an adsorbent for NH3 gas. After adsorbing six NH3 molecules, the Y-doped substrate had an average adsorption energy of −1.350eV and still maintained a good thermal stability at a temperature of 300 K. These results can provide insights into the development of sensors and adsorbents based on MXenes.