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Keywords = porous sheets

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19 pages, 3771 KiB  
Article
Effect of Carboxymethyl Konjac Glucomannan on the Gel Properties of Silver Carp Surimi: A Study on the Regulatory Mechanism of Substitution Degree
by Wenli Yan, Zhihan Ouyang, Xiaoying Luo, Rankun Xiao, Siqiao Liao, Fatang Jiang, Yonghui Li, Shanbai Xiong, Tao Yin and Xiangwei Zhu
Foods 2025, 14(15), 2715; https://doi.org/10.3390/foods14152715 (registering DOI) - 1 Aug 2025
Viewed by 196
Abstract
Freshwater surimi typically exhibits poor gel-forming capability and is prone to gel deterioration, limiting its applications in food products. This study successfully prepared silver carp surimi gels with improved gel strength and water-holding capacity (WHC) using carboxymethyl konjac glucomannan (CKGM) as a functional [...] Read more.
Freshwater surimi typically exhibits poor gel-forming capability and is prone to gel deterioration, limiting its applications in food products. This study successfully prepared silver carp surimi gels with improved gel strength and water-holding capacity (WHC) using carboxymethyl konjac glucomannan (CKGM) as a functional modifier. Furthermore, the regulatory mechanism of CKGM with different degrees of substitution (DS) on the gel properties of silver carp surimi was systematically investigated. Results demonstrated that DS significantly influenced gel strength, WHC, and microstructure. CKGM (DS = 0.21%) substantially enhanced the gel strength and WHC through strengthened hydrophobic interactions and hydrogen-bond networks. However, CKGM with a higher DS (0.41%) induced a steric hindrance effect, decreasing elastic modulus and WHC and resulting in a more porous gel network. Raman spectroscopy analysis revealed that CKGM facilitated the conformational transition of myofibrillar proteins from α-helix to β-sheet, thereby improving the density of the gel network. The study provides theoretical foundations and technical guidance for the quality improvement of surimi products. Full article
(This article belongs to the Special Issue Food Proteins: Extraction, Functions and Applications)
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18 pages, 6693 KiB  
Article
Tensile Resistance and Fracture Mechanisms of Silica Aerogels Reinforced by Nanotube–Graphene Hybrid Networks
by Lin Guo, Mu Du, Jiaqian Li, Wei Li, Mingyang Yang and Gongming Xin
Gels 2025, 11(6), 471; https://doi.org/10.3390/gels11060471 - 19 Jun 2025
Viewed by 370
Abstract
Despite their outstanding thermal insulation and ultralight structure, silica aerogels suffer from inherent mechanical fragility, making the investigation of their mechanical behavior crucial for expanding their practical utility in advanced applications. To enhance their mechanical performance, this study introduces a dual-phase reinforcement strategy [...] Read more.
Despite their outstanding thermal insulation and ultralight structure, silica aerogels suffer from inherent mechanical fragility, making the investigation of their mechanical behavior crucial for expanding their practical utility in advanced applications. To enhance their mechanical performance, this study introduces a dual-phase reinforcement strategy by anisotropically incorporating carbon nanotubes (CNTs) and graphene oxide (GO) sheets into the aerogel matrix. Using molecular dynamic simulations, we systematically investigate the tensile behavior and pore structure evolution of these hetero-structured composites. The results reveal a non-monotonic dependence of tensile strength on loading ratio, distinguishing three strain-dependent reinforcement regimes. High loading content (11.1%) significantly improves strength under low strain (0–26%), whereas low loading levels (1.8%) are more effective at preserving structural integrity under large strain (44–50%). Moderate loading (5.1%) yields balanced performance in intermediate regimes. While increasing carbon content reduces initial pore size by partially filling the framework, tensile deformation leads to interfacial debonding and the formation of larger pores due to CNT–GO hybrid structure interactions. This work elucidates a dual reinforcement mechanism—physical pore confinement and interfacial coupling—highlighting the critical role of nanostructure geometry in tuning strain-specific mechanical responses. The findings provide mechanistic insights into anisotropic nanocomposite behavior and offer guidance for designing robust porous materials for structural and functional applications. Full article
(This article belongs to the Special Issue Aerogels: Synthesis and Applications)
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8 pages, 2235 KiB  
Article
In Situ Synthesis of Copper Nanoparticles on Biocarbon Sheets for Surface-Enhanced Raman Scattering
by Jianqiang Wei, Zelong Zhou, Junchao Qian, Yaping Wang, Jun Chen and Yunfei Sun
Nanomaterials 2025, 15(12), 944; https://doi.org/10.3390/nano15120944 - 18 Jun 2025
Viewed by 351
Abstract
A copper nanoparticles@porous biocarbon substrate was designed for Surface-Enhanced Raman Spectroscopy (SERS) via a simple reduction method. In the detection of three trace antibiotics, the substrate exhibits a very high Raman enhancement efficiency. This is partly because the biocarbon is rich in meso-micropores, [...] Read more.
A copper nanoparticles@porous biocarbon substrate was designed for Surface-Enhanced Raman Spectroscopy (SERS) via a simple reduction method. In the detection of three trace antibiotics, the substrate exhibits a very high Raman enhancement efficiency. This is partly because the biocarbon is rich in meso-micropores, which can rapidly trap target molecules. On the other hand, the copper nanoparticles embedded on the surface of the carbon sheets generate a large number of plasmonic hotspots, leading to an increase in Raman signal intensity. These results suggest that this substrate has utility for SERS applications in food safety, medicine, and water pollution detection. Full article
(This article belongs to the Section 2D and Carbon Nanomaterials)
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20 pages, 14795 KiB  
Article
Inkjet-Printed Conductive Patterns on Electrospun Substrates for the Modular Fabrication of Nonplanar Circuits
by Fabricio N. Molinari, Emanuel Bilbao and Leandro N. Monsalve
Appl. Nano 2025, 6(2), 10; https://doi.org/10.3390/applnano6020010 - 18 Jun 2025
Viewed by 449
Abstract
Placing printed conductive patterns onto nonplanar substrates is a challenging task. In this work, we tested a simple method for depositing inkjet-printed conductive patterns onto 3D-printed pieces with cavities and sharp edges. First, a silver nanoparticle ink was used to print conductive patterns [...] Read more.
Placing printed conductive patterns onto nonplanar substrates is a challenging task. In this work, we tested a simple method for depositing inkjet-printed conductive patterns onto 3D-printed pieces with cavities and sharp edges. First, a silver nanoparticle ink was used to print conductive patterns onto a flexible and porous substrate made of electrospun polycaprolactone (PCL). Then, the printed patterns were transferred to 3D-printed pieces made of polylactic acid (PLA) by temperature-promoted adhesion. Finally, the printed patterns were cured to render them conductive. The influence of the number of printed layers on their electrical and mechanical properties was evaluated. The printed patterns were also transferred to flexible substrates, such as thermoplastic polyurethane (TPU) and polyethylene terephthalate (PET) sheets, achieving conductivity after curing. Moreover, the printed patterns were effective for modular interconnection among successive transferred patterns, since it was possible to achieve electrical contact between them during the transfer process. Full article
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13 pages, 5872 KiB  
Article
In Vivo Cell Migration and Growth Within Electrospun Porous Nanofibrous Scaffolds with Different Pore Sizes in a Mouse Pouch Model
by David C. Markel, Therese Bou-Akl, Bin Wu, Pawla Pawlitz, Xiaowei Yu, Liang Chen, Tong Shi and Weiping Ren
J. Funct. Biomater. 2025, 16(5), 181; https://doi.org/10.3390/jfb16050181 - 14 May 2025
Viewed by 607
Abstract
Cellular infiltration into traditional electrospun nanofibers (NFs) is limited due to their dense structures. We were able to obtain polycaprolactone (PCL) NFs with variable and defined pore sizes and thicknesses by using a customized programmed NF collector that controls the moving speed during [...] Read more.
Cellular infiltration into traditional electrospun nanofibers (NFs) is limited due to their dense structures. We were able to obtain polycaprolactone (PCL) NFs with variable and defined pore sizes and thicknesses by using a customized programmed NF collector that controls the moving speed during electrospinning. NFs obtained by this method were tested in vitro and have shown better cell proliferation within the NFs with larger pore sizes. This study investigated in vivo host cell migration and neovascularization within implanted porous PCL NF discs using a mouse pouch model. Four types of PCL NFs were prepared and classified based on the electrospinning speed: NF-zero (static control), NF-low (0.085 mm/min), NF-mid (0.158 mm/min) and NF-high (0.232 mm/min) groups. With the increase in the speed, we observed an increase in the pore area; NF-zero (11.6 ± 6.2 μm2), NF-low (37.4 ± 28.6 μm2), NF-mid (67.6 ± 54.8 μm2), and NF-high (292.3 ± 286.5 μm2) groups. The NFs were implanted into air pouches of BALB/cJ mice. Mice without NFs served as control. Animals were sacrificed at 7 and 28 days after the implantation. Pouch tissues with implanted NFs were collected for histology (n = three per group and time point). The efficiency of the tissue penetration into PCL NF sheets was closely linked to the pore size and area. NFs with the highest pore area had more efficient tissue migration and new blood vessel formation compared to those with a smaller pore area. No newly formed blood vessels were observed in NF-zero sheets up to 28 days. We believe that a porous NF scaffold with a controllable pore size and thickness has great potential for tissue repair/regeneration and for other healthcare applications. Full article
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11 pages, 8235 KiB  
Article
Performance Improvement of Vertical Channel Indium–Gallium–Zinc Oxide Thin-Film Transistors Using Porous MXene Electrode
by Wanqiang Fu, Qizhen Chen, Peng Gao, Linqin Jiang, Yu Qiu, Dong-Sing Wuu, Ray-Hua Horng and Shui-Yang Lien
Energies 2025, 18(9), 2331; https://doi.org/10.3390/en18092331 - 2 May 2025
Viewed by 591
Abstract
The surface morphology of porous source electrodes plays a significant role in the performance of vertical channel indium–gallium–zinc oxide thin-film transistors (VC-IGZO-TFTs). This study systematically investigates the properties of porous MXene-based source electrodes and their impact on VC-IGZO-TFTs fabricated with varying MXene concentrations. [...] Read more.
The surface morphology of porous source electrodes plays a significant role in the performance of vertical channel indium–gallium–zinc oxide thin-film transistors (VC-IGZO-TFTs). This study systematically investigates the properties of porous MXene-based source electrodes and their impact on VC-IGZO-TFTs fabricated with varying MXene concentrations. As the MXene concentration increases, both the sheet resistance and porosity of the electrodes decrease. VC-IGZO-TFTs based on a 3.0 mg/mL MXene concentration exhibit optimal electrical performance, with a threshold voltage (Vth) of 0.16 V, a subthreshold swing (SS) of 0.20 V/decade, and an on/off current ratio (Ion/Ioff) of 4.90 × 105. Meanwhile, the VC-IGZO-TFTs exhibit excellent electrical reliability and mechanical stability. This work provides a way to analyze the influence of sheet resistance and porosity on the performance of VC-IGZO-TFTs, offering a viable approach for enhancing device efficiency through porous MXene electrode engineering. Full article
(This article belongs to the Special Issue Advanced Technologies of Solar Cells: 2nd Edition)
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15 pages, 13259 KiB  
Article
N- and O- Doped Porous Carbon Nanosheets Prepared from Templating Methodology for Supercapacitors
by Baoning Zhu, Jinghua Liu, Qijun Zhong, Yaru Wen, Qianqian Dong, Yuhao Li, Qianqian Jin and Yao Lu
Polymers 2025, 17(9), 1198; https://doi.org/10.3390/polym17091198 - 27 Apr 2025
Viewed by 464
Abstract
Heteroatom-doped biomass-derived porous carbon materials show promising applications as electrode components in energy storage technologies. In this investigation, we present a template-assisted pyrolysis procedure to fabricate nitrogen–oxygen dual-doped carbon materials. Firstly, the precursor and template initially polymerized to form a white jelly-like gel, [...] Read more.
Heteroatom-doped biomass-derived porous carbon materials show promising applications as electrode components in energy storage technologies. In this investigation, we present a template-assisted pyrolysis procedure to fabricate nitrogen–oxygen dual-doped carbon materials. Firstly, the precursor and template initially polymerized to form a white jelly-like gel, which was freeze-dried to create a nanosheet-assembled structure. Subsequent high-temperature pyrolysis induced the formation of a porous structure with nanosheet morphology. The CMC-ZnK sample derived from the dual template of potassium citrate and zinc acetate pyrolyzed at 800 °C exhibits optimal electrochemical performance, delivering a specific capacitance of 271.4 F g−1 at 1 A g−1 in a three-electrode configuration, along with outstanding rate capability (90% retention, 244 F g−1 at 10 A g−1). The constructed supercapacitor demonstrated an energy density of 6.5 Wh kg−1 under a power density of 500 W kg−1. Furthermore, this study systematically investigated the performance variation mechanisms at different temperatures, revealing the relationship between structural composition and temperature in biomass materials. Full article
(This article belongs to the Section Polymer Applications)
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16 pages, 4785 KiB  
Article
Fabrication and Characterization of a Flexible Non-Enzymatic Electrochemical Glucose Sensor Using a Cu Nanoparticle/Laser-Induced Graphene Fiber/Porous Laser-Induced Graphene Network Electrode
by Taeheon Kim and James Jungho Pak
Sensors 2025, 25(7), 2341; https://doi.org/10.3390/s25072341 - 7 Apr 2025
Cited by 3 | Viewed by 1053
Abstract
We demonstrate a flexible electrochemical biosensor for non-enzymatic glucose detection under different bending conditions. The novel flexible glucose sensor consists of a Cu nanoparticle (NP)/laser-induced graphene fiber (LIGF)/porous laser-induced graphene (LIG) network structure on a polyimide film. The bare LIGF/LIG electrode fabricated using [...] Read more.
We demonstrate a flexible electrochemical biosensor for non-enzymatic glucose detection under different bending conditions. The novel flexible glucose sensor consists of a Cu nanoparticle (NP)/laser-induced graphene fiber (LIGF)/porous laser-induced graphene (LIG) network structure on a polyimide film. The bare LIGF/LIG electrode fabricated using an 8.9 W laser power shows a measured sheet resistance and thickness of 6.8 Ω/□ and ~420 μm, respectively. In addition, a conventional Cu NP electroplating method is used to fabricate a Cu/LIGF/LIG electrode-based glucose sensor that shows excellent glucose detection characteristics, including a sensitivity of 1438.8 µA/mM∙cm2, a limit of detection (LOD) of 124 nM, and a broad linear range at an applied potential of +600 mV. Significantly, the Cu/LIGF/LIG electrode-based glucose sensor exhibits a relatively high sensitivity, low LOD, good linear detection range, and long-term stability at bending angles of 0°, 45°, 90°, 135°, and 180°. Full article
(This article belongs to the Section Chemical Sensors)
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16 pages, 5156 KiB  
Article
The Heat-Induced Gel–Sol Transition in Coated Tofu: A Study on Protein Conformation and Microstructural Changes
by Xin Xie, Meng Li, Xinrui Diao, Saihua Sun, Ming Wen, Xiaohu Zhou, Liangzhong Zhao, Yang Li, Ping Lv, Bin Li, Xiaolong Shen, Zhanrui Huang, Hao Chen and Kuilin Zhang
Gels 2025, 11(4), 237; https://doi.org/10.3390/gels11040237 - 24 Mar 2025
Cited by 1 | Viewed by 919
Abstract
To enhance and stabilise the edible quality of coated tofu, this study explored the changes in the microstructure and intermolecular forces of coated tofu gel and sol under different heat treatments. It elucidated the phase transformation mechanism of coated tofu gel and sol [...] Read more.
To enhance and stabilise the edible quality of coated tofu, this study explored the changes in the microstructure and intermolecular forces of coated tofu gel and sol under different heat treatments. It elucidated the phase transformation mechanism of coated tofu gel and sol under heat treatment. The results showed that the protein structure unfolded, the fluorescence intensity decreased, and the protein solubility, surface hydrophobicity, and free sulfhydryl group content increased as the coated tofu gel transformed to sol. Disulfide bonding and hydrophobic interactions were the primary intermolecular forces in the heat-induced gel–sol transition. FTIR showed that the content of β-sheets decreased significantly during gel–sol transformation, while the content of β-turns, α-helices and random coils increased significantly. Most remained relatively stable during the gel–sol transformation process, with only the A and B subunits of the 11S protein decreasing slightly. Their reduction became significant when the temperature reached 200 °C. Additionally, the high-temperature heat treatment promoted the gel–sol transition of the coated tofu, with its cross-section gradually transforming from a porous network structure to a more uniform and smooth texture during heat treatment process. The findings of this study provide a theoretical basis for improving the quality of coated tofu by optimising heat treatment parameters, laying the groundwork for future advancements in the development of pre-heat-treated coated tofu. Full article
(This article belongs to the Special Issue Advances in Protein Gels and Their Applications)
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18 pages, 5889 KiB  
Article
Glass Fiber-Reinforced Polypropylene Composites with High Solar Reflectance for Thermal Insulation Applications
by Csenge Vámos and Tamás Bárány
Polymers 2025, 17(3), 274; https://doi.org/10.3390/polym17030274 - 22 Jan 2025
Viewed by 1118
Abstract
Reflective thermal insulation layers can offer an energy-efficient strategy for preventing temperature rises by reflecting sunlight on surfaces. Our previous study presented a novel solvent-based method to prepare porous polypropylene (PP) with high solar reflectivity. However, the stiffness and strength of the neat [...] Read more.
Reflective thermal insulation layers can offer an energy-efficient strategy for preventing temperature rises by reflecting sunlight on surfaces. Our previous study presented a novel solvent-based method to prepare porous polypropylene (PP) with high solar reflectivity. However, the stiffness and strength of the neat porous PP were insufficient for thermal insulation applications, as mechanical loads from installation and environmental factors limit the applicability of such products. This paper addresses this gap by applying our solvent-based surface modification technology to glass fiber (GF)-reinforced PP composite sheets, creating a previously unexplored system. While the enhanced modulus and strength aligned with expectations, the micro- and nano-structured porous outer layers situated below the skin layer of the sheets, the refractive index mismatch between the PP matrix and the GF, and the size of the GF delivered a notable advancement in reflective thermal insulation performance. The combined effect of 30 wt% GF, nucleating agents, and surface modification resulted in a highly porous surface layer featuring spherulite sizes of 0.5–2.0 μm. With these combined effects, we achieved a modulus value of ~4 GPa, a tensile strength of 60 MPa, and an average solar reflectance of up to 94%. Thermal insulation performance measurements demonstrated that the registered inner temperature was lower by 24.1 °C compared to neat PP sheets. These combined effects demonstrate the potential of our solvent-based surface modification technology to develop cost-effective, porous PP composite sheets for efficient reflective thermal insulation. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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17 pages, 8297 KiB  
Article
Deformation Behavior of Inconel 625 Alloy with TPMS Structure
by Kangning Xu, Jiahui Cao, Zhiwei Zheng, Rusheng Zhao, Gaopeng Xu, Hao Wang, Jincheng Wang, Boyoung Hur and Xuezheng Yue
Materials 2025, 18(2), 396; https://doi.org/10.3390/ma18020396 - 16 Jan 2025
Cited by 2 | Viewed by 1041
Abstract
Triply periodic minimal surfaces (TPMSs) are known for their smooth, fully interconnected, and naturally porous characteristics, offering a superior alternative to traditional porous structures. These structures often suffer from stress concentration and a lack of adjustability. Using laser powder bed fusion (LPBF), we [...] Read more.
Triply periodic minimal surfaces (TPMSs) are known for their smooth, fully interconnected, and naturally porous characteristics, offering a superior alternative to traditional porous structures. These structures often suffer from stress concentration and a lack of adjustability. Using laser powder bed fusion (LPBF), we have fabricated Inconel 625 sheet-based TPMS lattice structures with four distinct topologies: Primitive, IWP, Diamond, and Gyroid. The compressive responses and energy absorption capabilities of the four lattice designs were meticulously evaluated. The discrepancies between theoretical predictions and the fabricated specimens were precisely quantified using the Archimedes’ principle for volume displacement. Subsequently, the LPBF-manufactured samples underwent uniaxial compression tests, which were complemented by numerical simulation for validation. The experimental results demonstrate that the IWP lattice consistently outperformed the other three configurations in terms of yield strength. Furthermore, when comparing energy absorption efficiencies, the IWP structures were confirmed to be more effective and closer to the ideal performance. An analysis of the deformation mechanisms shows that the IWP structure characteristically failed in a layer-by-layer manner, distinct from the other structures that exhibited significant shear banding. This distinct behavior was responsible for the higher yield strength (113.16 MPa), elastic modulus (735.76 MPa), and energy absorption capacity (9009.39 MJ/m3) observed in the IWP configuration. To examine the influence of porosity on structural performance, specimens with two varying porosities (70% and 80%) were selected for each of the four designs. Ultimately, the mechanical performance of Inconel 625 under compression was assessed both pre- and post-deformation to elucidate its impact on the material’s integrity. Full article
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11 pages, 2311 KiB  
Article
Ion-Replacement Strategy in Preparing Bi-Based MOF and Its Derived Bi/C Composite for Efficient Sodium Storage
by Zhenpeng Zhu, Shuya Zhang, Kuan Shen, Fu Cao, Qinghong Kong and Junhao Zhang
Batteries 2025, 11(1), 2; https://doi.org/10.3390/batteries11010002 - 24 Dec 2024
Viewed by 1177
Abstract
To address large volumetric expansion and low conductivity of bismuth-based anodes, an ion-replacement technique is proposed to prepare Bi/C composites, using 1,3,5-benzenetricarboxylicacid (H3BTC) based metal–organic framework as precursors. The characterizations reveal that the Bi/C composite derived from Cu-H3BTC is [...] Read more.
To address large volumetric expansion and low conductivity of bismuth-based anodes, an ion-replacement technique is proposed to prepare Bi/C composites, using 1,3,5-benzenetricarboxylicacid (H3BTC) based metal–organic framework as precursors. The characterizations reveal that the Bi/C composite derived from Cu-H3BTC is a sheet structure with the size of 150 nm, and Bi nanoparticles are uniformly dispersed in carbon sheets. When assessed as anode material for sodium ion batteries (SIBs), a sheet-like Bi/C anode exhibits superior sodium storage performance. It delivers a reversible capacity of 254.6 mAh g−1 at 1.0 A g−1 after 100 cycles, and the capacity retention is high at 91%. Even at 2.0 A g−1, the reversible capacity still reaches 242.8 mAh g−1. The efficient sodium storage performance benefits from the uniform dispersion of Bi nanoparticles in the carbon matrix, which not only provides abundant active sites but also alleviates the volume expansion. Meanwhile, porous carbon sheets can increase the electrical conductivity and accelerate the electrochemical reaction kinetics. Full article
(This article belongs to the Special Issue Thermal Safety of Lithium Ion Batteries—2nd Edition)
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14 pages, 2101 KiB  
Article
Fabrication of Porous MXene/Cellulose Nanofibers Composite Membrane for Maximum Osmotic Energy Harvesting
by Sha Wang, Zhe Sun, Mehraj Ahmad and Mengyu Miao
Int. J. Mol. Sci. 2024, 25(23), 13226; https://doi.org/10.3390/ijms252313226 - 9 Dec 2024
Cited by 1 | Viewed by 1502
Abstract
Two-dimensional (2D) nanofluidic channels are emerging as potential candidates for harnessing osmotic energy from salinity gradients. However, conventional 2D nanofluidic membranes suffer from high transport resistance and low ion selectivity, leading to inefficient transport dynamics and limiting energy conversion performance. In this study, [...] Read more.
Two-dimensional (2D) nanofluidic channels are emerging as potential candidates for harnessing osmotic energy from salinity gradients. However, conventional 2D nanofluidic membranes suffer from high transport resistance and low ion selectivity, leading to inefficient transport dynamics and limiting energy conversion performance. In this study, we present a novel composite membrane consisting of porous MXene (PMXene) nanosheets featuring etched nanopores, in conjunction with cellulose nanofibers (CNF), yielding enhancement in ion flux and ion selectivity. A mild H2O2 oxidant is employed to etch and perforate the MXene sheets to create a robust network of cation transportation nanochannels that effectively reduces the energy barrier for cation transport. Additionally, CNF with a unique nanosize and high charge density further enhances the charge density and mechanical stability of the nanofluidic system. Under neutral pH and room temperature, the PMXene/CNF membrane demonstrates a maximum output power density of 0.95 W·m−2 at a 50-fold KCl gradient. Notably, this represents a 43% improvement over the performance of the pristine MXene/CNF membrane. Moreover, 36 nanofluidic devices connected in series are demonstrated to achieve a stable voltage output of 5.27 V and power a calculator successfully. This work holds great promise for achieving sustainable energy harvesting with efficient osmotic energy conversion utilization. Full article
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11 pages, 1227 KiB  
Article
Sampling and Comparison of Extraction Techniques Coupled with Gas Chromatography–Mass Spectrometry (GC-MS) for the Analysis of Substrates Exposed to Explosives
by Himanshi Upadhyaya, Alexis J. Hecker and John V. Goodpaster
Chemosensors 2024, 12(12), 251; https://doi.org/10.3390/chemosensors12120251 - 29 Nov 2024
Viewed by 1648
Abstract
Explosive-detecting canines (EDCs) show high sensitivity in detecting explosives that they are trained to detect. The ability of canines to detect explosive residues to the parts per trillion level can sometimes result in nuisance alerts. These nuisance alerts can occur when various materials [...] Read more.
Explosive-detecting canines (EDCs) show high sensitivity in detecting explosives that they are trained to detect. The ability of canines to detect explosive residues to the parts per trillion level can sometimes result in nuisance alerts. These nuisance alerts can occur when various materials (i.e., substrates) are exposed to volatile organic compounds (VOCs) present in explosive mixtures, leading to contamination—the unintended absorption or adsorption of VOCs by the substrate. Chemical constituents such as taggant, plasticizer, and residual solvent in explosives are often composed of VOCs that canines are trained on to detect explosives. Composition C-4 (C4) is a common explosive that EDCs are trained to detect and hence is this study’s focus. Common VOCs of interest emitted from C4 include 2,3-dimethyl-2,3-dinitrobutane (DMNB), 2-ethyl-1 hexanol (2E1H), and cyclohexanone. In this study, we developed a protocol for comparing different substrates such as cotton, cardboard, wood, sheet metal, and glass that were exposed to volatiles from C4. 1-bromooctane (1-BO) was used as a single-odor compound to compare the complex odor originating from C4. Triplicates of substrates such as cotton, wood, cardboard, sheet metal, and glass were exposed to 1 g of C4 in a paint can for one week and the substrates were then extracted using various extraction methods such as liquid injection, direct SPME, and headspace analysis coupled with gas chromatography–mass spectrometry. An extraction time study was performed to determine the optimal extraction time for SPME analysis, and it was found to be 20 min. Comparison of extraction methods revealed that SPME surpassed other techniques as DMNB was found on all substrates using SPME. It was observed that porous substrates such as wood and cardboard have a higher retention capacity for volatiles in comparison to non-porous substrates such as sheet metal and glass. Finally, swabbing was evaluated as a sampling technique for the substrates of interest and the extracts were analyzed using the total vaporization–solid phase microextraction (TV-SPME) technique. No volatiles associated with C4 were identified on conducting a GC-MS analysis, suggesting that swabbing is not an ideal technique for analysis of substrates exposed to C4. Full article
(This article belongs to the Special Issue Detection of Volatile Organic Compounds in Complex Mixtures)
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26 pages, 13041 KiB  
Article
Carbon-Free H2 Production from Ammonia Decomposition over 3D-Printed Ni-Alloy Structures Activated with a Ru/Al2O3 Catalyst
by Cristina Italiano, Gabriel Marino, Minju Thomas, Benjamin Hary, Steve Nardone, Simon Richard, Assia Saker, Damien Tasso, Nicolas Meynet, Pierre Olivier, Fausto Gallucci and Antonio Vita
Processes 2024, 12(12), 2663; https://doi.org/10.3390/pr12122663 - 26 Nov 2024
Viewed by 2490
Abstract
Hydrogen, with its high energy density and zero greenhouse gas emissions, is an exceptional energy vector, pivotal for a sustainable energy future. Ammonia, serving as a practical and cost-effective hydrogen carrier, offers a secure method for hydrogen storage and transport. The decomposition of [...] Read more.
Hydrogen, with its high energy density and zero greenhouse gas emissions, is an exceptional energy vector, pivotal for a sustainable energy future. Ammonia, serving as a practical and cost-effective hydrogen carrier, offers a secure method for hydrogen storage and transport. The decomposition of ammonia into hydrogen is a crucial process for producing green hydrogen, enabling its use in applications ranging from clean energy generation to fueling hydrogen-powered vehicles, thereby advancing the transition to a carbon-free energy economy. This study investigates the catalytic performance of various 3D-printed porous supports based on periodic open cellular structures (POCS) and triply periodic minimal surface (TPMS) architecture manufactured from IN625 nickel alloy powder using the laser powder bed fusion (LPBF) technique. The POCS and TPMS, featuring geometries including BCC, Kelvin, and Gyroid, were analyzed for cell size, strut/sheet diameter, porosity, and specific surface area. Pressure drop analyses demonstrated correlations between structural parameters and fluid dynamics, with BCC structures exhibiting lower pressure drops due to their higher porosity and the open channel network. The dip/spin coating method was successfully applied to activate the supports with a commercial Ru/Al2O3 catalyst, achieving uniform coverage crucial for catalytic performance. Among the tested geometries, the Gyroid structure showed superior catalytic activity towards ammonia decomposition, attributed to its efficient mass transfer pathways. This study highlights the importance of structural design in optimizing catalytic processes and suggests the Gyroid structure as a promising candidate for improving reactor efficiency and compactness in hydrogen production systems. Full article
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