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ACS Omega Jun 2024With the development of high-rise and large-scale modern structures, traditional concrete has become a design limitation due to its excessive dead weight. High-strength...
With the development of high-rise and large-scale modern structures, traditional concrete has become a design limitation due to its excessive dead weight. High-strength lightweight concrete is being emphasized. Lightweight concrete has low density and the characteristics of a brittle material. This is an important factor affecting the strength and ductility of the lightweight concrete. To improve these shortcomings and proffer solutions, a three-phase composite lightweight concrete was prepared using a combination of tumbling and molding methods. This paper investigates the various influencing factors such as the stacking volume fraction of GFR-EMS, the type of fiber, and the content and length of fiber in the matrix. Studies have shown that the addition of fibers significantly increases the compressive strength of the concrete. The compressive strength of concrete with a 12 mm basalt fiber (BF) (1.5%) admixture is 9.08 MPa, which is 62.43% higher than that of concrete without the fiber admixture. The compressive strength was increased by 27.53 and 21.88% compared to concrete containing 3 mm BF (1.5%) and 0.5% BF (12 mm), respectively. Fibers can fill the pore defects within the matrix. Mutually overlapping fibers easily form a network structure to improve the bond between the cement matrix and the aggregate particles. The compressive strength of lightweight concrete with the addition of BF was 16.71% higher than that with the addition of polypropylene fiber (PPF) with the same length and content of fibers. BF has been shown to be more effective in improving the mechanical properties of concrete. In this work, the compressive mechanism and optimum preparation parameters of a three-phase composite lightweight concrete were analyzed through compression tests. This provides some insights into the development of lightweight concrete.
PubMed: 38947776
DOI: 10.1021/acsomega.3c10076 -
IScience Jun 2024experiments and cryo-EM structures of p97 and its cofactor, Ufd1/Npl4 (UN), elucidated substrate processing. Yet, the structural transitions and the related ATPase...
experiments and cryo-EM structures of p97 and its cofactor, Ufd1/Npl4 (UN), elucidated substrate processing. Yet, the structural transitions and the related ATPase cycle upon UN binding remain unresolved. We captured two discrete conformations: One in which D1 protomers are ATP bound, while the D2 subunits are in the ADP state, presumably required for substrate engagement with the D2 pore; and a heterologous nucleotide state within the D1 ring in which only two NTDs are in the "up" ATP state that favors UN binding. Further analysis suggests that initially, UN binds p97's non-symmetrical conformation, this association promotes a structural transition upon which five NTDs shift to an "up" state and are poised to bind ATP. The UBXL domain of Npl4 was captured bound to an NTD in the ADP state, demonstrating a conformation that may provide directionality to incoming substrate and introduce the flexibility needed for substrate processing.
PubMed: 38947518
DOI: 10.1016/j.isci.2024.110061 -
IScience Jun 2024In recent years, vegetation plays a key role in landslide stability under extreme rainfall in the Three Gorges Reservoir area, so it is very important to identify the...
In recent years, vegetation plays a key role in landslide stability under extreme rainfall in the Three Gorges Reservoir area, so it is very important to identify the mechanism of vegetation slope protection. This study takes wildcat landslide in Three Gorges Reservoir area as the research object, using indoor landslide model test and building monitoring systems such as stress field, displacement field, and soil erosion, to illustrate the protective effect of typical vegetation. Furthermore, Bermuda cover effectively reduces pore water pressure, pore soil pressure, displacement, and turbidity. In particular, the three stages of interception and buffering of rainfall by stems and leaves, infiltration and absorption of rainfall by the root system, and the reinforcement of the slope against sliding forces by the root system have been divided. Moreover, these findings offer valuable preliminary insights for guiding landslide mitigation strategies in the Three Gorges Reservoir area.
PubMed: 38947505
DOI: 10.1016/j.isci.2024.110057 -
International Journal of Nanomedicine 2024Functional inorganic nanomaterials (NMs) are widely exploited as bioactive materials and drug depots. The lack of a stable form of application of NMs at the site of skin...
PURPOSE
Functional inorganic nanomaterials (NMs) are widely exploited as bioactive materials and drug depots. The lack of a stable form of application of NMs at the site of skin injury, may impede the removal of the debridement, elevate pH, induce tissue toxicity, and limit their use in skin repair. This necessitates the advent of innovative wound dressings that overcome the above limitations. The overarching objective of this study was to exploit strontium-doped mesoporous silicon particles (PSiSr) to impart multifunctionality to poly(lactic-co-glycolic acid)/gelatin (PG)-based fibrous dressings (PG@PSiSr) for excisional wound management.
METHODS
Mesoporous silicon particles (PSi) and PSiSr were synthesized using a chemo-synthetic approach. Both PSi and PSiSr were incorporated into PG fibers using electrospinning. A series of structure, morphology, pore size distribution, and cumulative pH studies on the PG@PSi and PG@PSiSr membranes were performed. Cytocompatibility, hemocompatibility, transwell migration, scratch wound healing, and delineated angiogenic properties of these composite dressings were tested in vitro. The biocompatibility of composite dressings in vivo was assessed by a subcutaneous implantation model of rats, while their potential for wound healing was discerned by implantation in a full-thickness excisional defect model of rats.
RESULTS
The PG@PSiSr membranes can afford the sustained release of silicon ions (Si) and strontium ions (Sr) for up to 192 h as well as remarkably promote human umbilical vein endothelial cells (HUVECs) and NIH-3T3 fibroblasts migration. The PG@PSiSr membranes also showed better cytocompatibility, hemocompatibility, and significant formation of tubule-like networks of HUVECs in vitro. Moreover, PG@PSiSr membranes also facilitated the infiltration of host cells and promoted the deposition of collagen while reducing the accumulation of inflammatory cells in a subcutaneous implantation model in rats as assessed for up to day 14. Further evaluation of membranes transplanted in a full-thickness excisional wound model in rats showed rapid wound closure (PG@SiSr vs control, 96.1% vs 71.7%), re-epithelialization, and less inflammatory response alongside skin appendages formation (eg, blood vessels, glands, hair follicles, etc.).
CONCLUSION
To sum up, we successfully fabricated PSiSr particles and prepared PG@PSiSr dressings using electrospinning. The PSiSr-mediated release of therapeutic ions, such as Si and Sr, may improve the functionality of PLGA/Gel dressings for an effective wound repair, which may also have implications for the other soft tissue repair disciplines.
Topics: Gelatin; Animals; Strontium; Wound Healing; Bandages; Polylactic Acid-Polyglycolic Acid Copolymer; Skin; Porosity; Rats; Humans; Silicon; Rats, Sprague-Dawley; Mice; Human Umbilical Vein Endothelial Cells; Male; Biocompatible Materials
PubMed: 38946883
DOI: 10.2147/IJN.S460177 -
Misleading Pore Size Measurements in Gelatin and Alginate Hydrogels revealed by Confocal Microscopy.Tissue Engineering. Part C, Methods Jul 2024It is a well-documented phenomenon that the porous structure of hydrogels observed with vacuum-based imaging techniques is generated during the freezing and drying...
It is a well-documented phenomenon that the porous structure of hydrogels observed with vacuum-based imaging techniques is generated during the freezing and drying process employed prior to observation. Nevertheless, vacuum-based techniques, such as scanning electron microscopy (SEM), are still being commonly used to measure pore sizes in hydrogels, which is often not representative of the actual pore size in hydrated conditions. The frequent underestimation of the impact of freezing and drying on hydrogel structures could stem from a lack of cross-fertilization between materials science and biomedical or food science communities, or from the simplicity and visually appealing nature of SEM imaging which may lead to an overemphasis on its use. Our study provides a straightforward and impactful way of pinpointing this phenomenon exploiting two hydrogels ubiquitously applied in tissue engineering, including gelatin methacryloyl (GelMA) and alginate as proof-of-concept hydrogels. By comparing images of the samples in the native hydrated state, followed by freezing, freeze-drying and rehydration using SEM and confocal microscopy, we highlight discrepancies between hydrogel pore sizes in the hydrated versus the dry state. To conclude, our study offers recommendations for researchers seeking insight in hydrogel properties and emphasizes key factors that require careful control when using SEM as a characterization tool.
PubMed: 38946552
DOI: 10.1089/ten.TEC.2024.0117 -
ACS Applied Materials & Interfaces Jul 2024Meeting the exacting demands of wound healing encompasses rapid coagulation, superior exudate absorption, high antibacterial efficacy, and imperative support for cell...
Meeting the exacting demands of wound healing encompasses rapid coagulation, superior exudate absorption, high antibacterial efficacy, and imperative support for cell growth. In this study, by emulating the intricate structure of natural skin, we prepare a multifunctional porous bilayer artificial skin to address these critical requirements. The bottom layer, mimicking the dermis, is crafted through freeze-drying a gel network comprising carboxymethyl chitosan (CMCs) and gelatin (GL), while the top layer, emulating the epidermis, is prepared via electrospinning poly(l-lactic acid) (PLLA) nanofibers. With protocatechuic aldehyde and gallium ion complexation (PA@Ga) as cross-linking agents, the bottom PA@Ga-CMCs/GL layer featured an adjustable pore size (78-138 μm), high hemostatic performance (67s), and excellent bacterial inhibition rate (99.9%), complemented by an impressive liquid-absorbing capacity (2000% swelling rate). The top PLLA layer, with dense micronanostructure and hydrophobic properties, worked as a shield to effectively thwarted liquid or bacterial penetration. Furthermore, accelerated wound closure, reduced inflammatory responses, and enhanced formation of hair follicles and blood vessels are achieved by the porous artificial skin covered on the surface of wound. Bilayer artificial skin integrates the advantages of nanofibers and freeze-drying porous materials to effectively replicate the protective properties of the epidermal layer of the skin, as well as the cell migration and tissue regeneration of the dermis. This bioabsorbable artificial skin demonstrates structural and functional comparability to real skin, which would advance the field of wound care through its multifaceted capabilities.
PubMed: 38946497
DOI: 10.1021/acsami.4c05074 -
Selective Xenon Recovery Using Aluminum-Based Metal-Organic Frameworks with Conserved Pore Topology.ACS Applied Materials & Interfaces Jun 2024Xenon (Xe) is a commercially valuable element found in trace amounts in the off-gas from used nuclear fuel. Recovering Xe from these streams provides a cost-effective...
Xenon (Xe) is a commercially valuable element found in trace amounts in the off-gas from used nuclear fuel. Recovering Xe from these streams provides a cost-effective means to increase its supply. However, achieving high-purity Xe recovery is challenging due to the need for separation from nearly identical krypton (Kr). Metal-organic frameworks (MOFs), a class of crystalline porous materials, show potential to separate Xe and Kr by utilizing differences in their kinetic diameters, allowing for selective separation. In this work, we study the impact of pore aperture and volume on selective Xe recovery using four robust aluminum MOFs: Al-PMOF, Al-PyrMOF, Al-BMOF and MIL-120, all with conserved structural topology. The pore topology in each MOF is dictated by the dimensions of the tetracarboxylate ligand employed, with larger ligands leading to MOFs with increased pore size and volume. Our experimental and computational investigations revealed that MIL-120 exhibits the highest affinity (21.94 = 21.94 mmol g bar) for Xe among all MOFs, while Al-BMOF demonstrates the highest Xe/Kr selectivity of 14.34. We evaluated the potential of both MIL-120 and Al-BMOF for Xe recovery through breakthrough analysis using a mixture of 400 ppm Xe:40 ppm Kr. Our results indicate that due to its larger pore volume, Al-BMOF captured more Xe than MIL-120, demonstrating superior Xe/Kr separation efficiency.
PubMed: 38946070
DOI: 10.1021/acsami.4c06215 -
Chemistry (Weinheim An Der Bergstrasse,... Jun 2024Tailoring the properties of cellulose aerogel beads was investigated in the present study by using weak organic acids as coagulants. Three different weak acids were...
Tailoring the properties of cellulose aerogel beads was investigated in the present study by using weak organic acids as coagulants. Three different weak acids were specifically chosen, acetic acid, lactic acid and citric acid. For comparative studies, a strong acid, hydrochloric acid was examined. The production of aerogel beads by conventional dropping technique was controlled and optimized for weak acids. Aerogels were characterized by density analyses, scanning electron microscopy, nitrogen adsorption-desorption analysis, X-ray powder diffractometry and IR spectroscopy. In common, all the aerogel beads showed interconnected nanofibrillar network, high specific surface area, high pore volume, high porosity and meso- and macroporous structure. In particular, when the weakest acid (acetic acid) was used as coagulant in the regeneration bath, the lowest shrinkage was observed. As a result, the cellulose aerogel beads produced from acetic acid showed the highest values of specific surface area (423 m2·g-1) and pore volume (3.6 cm3·g-1). The porous structure can be tuned by the choice of regeneration bath having either strong acid or high concentration of weak acid. The aerogel beads were pure and showed cellulose II crystallinity. Hence this study paves an alternative path way to tailor the properties of cellulose aerogel beads.
PubMed: 38945825
DOI: 10.1002/chem.202401794 -
International Journal of Biological... Jun 2024To replace traditional petrochemical-based thermal insulation materials, in this work, the chitosan (CHI)/alginate (ALG) (CA) aerogels with three-dimensional...
Construction of chitosan/alginate aerogels with three-dimensional hierarchical pore network structure via hydrogen bonding dissolution and covalent crosslinking synergistic strategy for thermal management systems.
To replace traditional petrochemical-based thermal insulation materials, in this work, the chitosan (CHI)/alginate (ALG) (CA) aerogels with three-dimensional hierarchical pore network structure were constructed by compositing CHI and ALG using a synergistic strategy of hydrogen bonding dissolution and covalent crosslinking. The structure and properties were further regulated by crosslinking the CA aerogels with epichlorohydrin (ECH). The CA aerogels exhibited various forms of covalent crosslinking, hydrogen bonding and electrostatic interactions, with hydrogen bonding content reaching 79.12 %. The CA aerogels showed an excellent three-dimensional hierarchical pore network structure, with an average pore size minimum of 15.92 nm. The structure regulation of CA aerogels obtained excellent compressive properties, with an increase of stress and strain by 137.61 % and 45.05 %, which can support a heavy object 5000 times its weight. Additionally, CA aerogels demonstrate excellent thermal insulation properties and low thermal conductivity, comparable to commercially available insulation materials. More importantly, CA aerogels have good cyclic insulation stability and thermal properties, and they have a flame retardancy rating of V-0, which shows the stability of insulation properties and excellent safety. CA aerogels provide new ideas for the development of biomass thermal insulation materials and are expected to be candidates for thermal management applications.
PubMed: 38945720
DOI: 10.1016/j.ijbiomac.2024.133367 -
Food Research International (Ottawa,... Aug 2024The effect of varying proportions (w/w) of natural aromatic extract of black tea (NAEBT) with pre-emulsification on the water-holding capacity (WHC) of pork meat batter...
The effect of varying proportions (w/w) of natural aromatic extract of black tea (NAEBT) with pre-emulsification on the water-holding capacity (WHC) of pork meat batter was investigated. The addition of NAEBT significantly reduced the cooking loss (CL) of pork meat batter from 23.95 % to 18.30 % (P < 0.05). Furthermore, NAEBT with pre-emulsification significantly improved the color stability and increased the springiness (P < 0.05). The results of TBARS and carbonyls indicated that NAEBT with pre-emulsification significantly alleviated oxidative damage to proteins (P < 0.05), resulting in an increased level of β-sheet (P < 0.05), as confirmed by FT-IR analysis. As a result, the water mobility of pork meat batter was restricted (P < 0.05), resulting in an increase in the energy storage modulus (P < 0.05) and a decrease in the pore size. In summary, the WHC of pork meat batter was improved by the antioxidant effect of the NAEBT.
Topics: Water; Plant Extracts; Pork Meat; Animals; Tea; Meat Products; Antioxidants; Swine; Cooking; Thiobarbituric Acid Reactive Substances; Spectroscopy, Fourier Transform Infrared
PubMed: 38945580
DOI: 10.1016/j.foodres.2024.114627