Uniform Pore Distribution Research Articles

Effect of Ultrasound Combined with Glycerol-Mediated Low-Sodium Curing on the Quality and Protein Structure of Pork Tenderloin.

Considering the hazards of high salt intake and the current status of research on low-sodium meat products, this study was to analyze the effect of ultrasound combined with glycerol-mediated low-sodium salt curing on the quality of pork tenderloin by analyzing the salt content, water activity (aw), cooking loss, and texture. The results of scanning electron microscope (SEM) analysis, Raman spectroscopy, ultraviolet fluorescence, and surface hydrophobicity were proposed to reveal the mechanism of the effect of combined ultrasound and glycerol-mediated low sodium salt curing on the quality characteristics of pork tenderloin. The results showed that the co-mediated curing could reduce salt content, aw, and cooking loss (p < 0.05), improve texture and enhance product quality. Compared with the control group, the co-mediated curing increased the solubility of the myofibrillar protein, improved the surface hydrophobicity of the protein, increased the content of reactive sulfhydryl groups (p < 0.05), and changed the protein structure. The SEM results showed that the products treated using a co-mediated curing process had a more detailed and uniform pore distribution. These findings provide new insights into the quality of ultrasonic-treated and glycerol-mediated low-salt cured meat products.

Foamability and mechanical properties of in situ submicron MgAl2O4p/Al composite foams by ultrasonic method

Composite aluminum foams, which are reinforced with submicron MgAl2O4 generated in situ using different weight percentages of SiO2 precursor (0.3, 0.5, and 0.7 wt%), were fabricated by stir casting and ultrasonic treatment (UT). Experimental results indicated that the microstructural constitution of all the foams prepared was composed of α-Al, MgAl2O4 and Fe based intermetallics. More uniform pore distribution and better stability were achieved in the foams corresponding to maximum SiO2 addition. The mechanical properties of the MgAl2O4p/Al composite foams were investigated by the quasi-static compression test. The plateau stress and energy absorption are enhanced with increasing SiO2 addition. These are mainly due to the presence of submicron particles in the microstructure.

Finite Element Analysis for the Static Response of Functionally Graded Porous Sandwich Beams

In this paper, the finite element method is used to analyze the static response of the functionally graded porous (FGP) sandwich beams subjected to uniformly distributed loads along the beam span. The core of the beam is made up of functionally graded porous material while the top and bottom layers are made up of isotropic homogenous materials. Uniform distribution and symmetric distribution of pores are used as two different types of porous material. Shear deformation is considered in the analysis by utilizing BEAM189 in ANSYS which is a finite element package program. This element is based on the first-order shear deformation theory. The influence of porosity coefficient, boundary conditions, and type of the porous material on the static response of the considered structures is presented in detail. The results demonstrate that the porosity coefficient has an important impact on the static response of the FGP sandwich beams.

A comparative study of the optical and microstructural properties of suspension and atmospheric plasma sprayed thermal barrier coatings

Thermal radiation is an increasingly important issue for thermal barrier coating (TBC) applications in aircraft engine components. As operating temperatures increase, the radiative part of the heat load increases significantly faster than the conductive portion; as such, TBCs may not be as efficient in protecting their underlying heat-sensitive metallic components. To address this issue, new coating morphologies must be investigated. In this study, we compare the optical performance of atmospheric plasma sprayed (APS) and suspension plasma sprayed (SPS) yttria-stabilized zirconia (YSZ) coatings. First, we extract their absorption and scattering coefficients from spectrophotometry measurements via the inverse adding-doubling (IAD) method. The microstructure of the coatings is then analyzed and compared using scanning electron microscopy (SEM) and mercury infiltration porosimetry (MIP). SPS samples are found to offer higher radiation blocking properties due to a more uniform distribution of pores with an average smaller pore diameter than the APS samples. This results in an overall higher pore density, with each pore interface acting as a scattering site, and therefore a higher propensity for scattering events.

Core-shell assembly of ZrO2 nanoparticles with ionic liquid: a novel and highly efficient heterogeneous catalysts for Biginelli and esterification reactions.

Imidazolium sulfonic acid chloride grafted ZrO2 nanoparticles (ZrO2-IL) were synthesized through facile post-treatment of the nanoparticles with the imidazolium-sulfonic acid chloride ionic liquid. The immobilization of the ionic liquid over the ZrO2 nanoparticles was evident from the XRD, SEM, TEM, Raman, BET, and XPS analysis. The results obtained from the XRD analysis clearly show that the catalyst has an orthorhombic structure and from the BET analysis it is evident that the surface is mesoporous with uniform pore sizes and pore distribution. Further evidence of immobilization of ionic liquid over the ZrO2 NPs was obtained from the SEM, TEM, XPS, and Raman analysis. Under mild conditions, the synthesized heterostructure was used in the acid-catalyzed esterification of different acids. The ZrO2-IL catalyst converts 99% of the acid to ester with a 98.9% yield in 1h. The material was also shown to be highly efficient as catalyst for the Biginelli reaction under solvent-free conditions, with the catalyst for dihydropyrimidin-2(1H)-one (DHPMs) in 1h with 99.2% conversion and 99% yield. The synergy between the ionic liquid catalyst and the substrates increased the catalytic efficiency and resulted in high-yield product conversion. The mechanism of both transformation reactions was investigated, as well as the synergy between ionic liquid and ZrO2 nanoparticles for better catalytic efficiency was established.

4D study of liquid binder penetration dynamics in pharmaceutical powders using synchrotron X-ray micro computed tomography

The properties of pharmaceutical powders, and the liquid binder, directly influence the penetration behavior in the wet granulation process of the pharmaceutical industry. Conventional methods encounter challenges in understanding this fast process. In this work, an emerging synchrotron-based X-ray imaging technique (having fast imaging capability) was employed to investigate the internal process from 2D and 3D to real-time (in-situ with ms time intervals) 3D (also considered 4D) perspectives. Two commonly used excipients (lactose monohydrate (LMH) and microcrystalline cellulose (MCC)) were used to make binary mixtures with acetaminophen (APAP) as the active pharmaceutical ingredient (API). Isopropanol and water were employed as liquid binders in the single droplet impact method. Results showed that for most of the mixtures, the porosity increased at higher fractions of APAP. MCC mixtures experienced less agglomeration and more uniform pore distribution than LMH ones, resulting in a faster droplet penetration with isopropanol. Moreover, the imbibition-spreading studies showed that isopropanol penetration in MCC powders followed more unidirectional vertical movement than horizontal spreading. Our results also demonstrated that simultaneous granulation of LMH with water resulted in much slower penetration. This study revealed that synchrotron X-ray imaging can investigate 3D internal pore structures and how they affect the quantitively real-time internal penetration dynamics.

Synthesis of γ-graphyne by modified mechanochemistry with enhanced adsorption of organic dyes

The γ-graphyne is a new two-dimensional carbon nanomaterials with unique sp and sp2 hybridized carbon atoms, uniform distribution of nanotopological pores, and high degree of π-conjugation, making it a promising candidate in water pollutant treatment. Herein, γ-graphyne was synthesized by a modified mechanochemical method and used as adsorbents for removing of organic dyes. Raman spectra, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are performed to confirm the chemical structure and morphology of γ-graphyne. The maximum adsorption capacities of γ-graphyne for rhodamine B (RhB), methylene blue (MB) and congo red (CR) obtained through kinetic and isotherm analysis are 386.10, 357.14 and 254.45 mg/g, respectively，which are in good accordance with the experimental results of 383.64, 359.72 and 242.44 mg/g. The calculated adsorption energies of −20.0995, −12.5219 and −8.3647 kCal/mol, respectively, for RhB, MB and CR, which characterized the possible adsorption sites, give more deep understanding of the experimental results regarding the remarkable absorbability of γ-graphyne. Our work sheds light on synthesis of γ-graphyne for the future development of excellent adsorbents.

Preparation and Characterization of 3D Printed Porous 45S5 Bioglass Bioceramic for Bone Tissue Engineering Application.

Three-dimensional (3D) printing technology provides advanced technical support for designing personalized bone tissue engineering scaffold. In this study, two porous diffusing models, namely, average and layered perforated cylindrical scaffolds, were designed for bone tissue engineering scaffold. The designed models were fabricated by liquid crystal display mask stereolithography printing. Structural design and finite element mechanical analysis were conducted. 45S5 bioglass was selected as the raw material for preparing the printing inks for bone tissue engineering scaffolds. By adjusting the viscosity and temperature of the slurry, the maximum proportion of 45S5 bioglass (40 wt%) was added into the photosensitive resin for preparing 3D printing slurry. Our results indicated that an optimized sintering condition includes the debinding rate (0.5°C/min), and temperature raising rate (5°C/min) and sintering temperature (1100°C) were proposed to sinter 45S5 bioceramic scaffolds. The amorphous 45S5 bioglass showed good crystallization after sintering, and the scaffold porous structure showed good integrity. Micropores were observed in the struts which interconnected with each other. Moreover, the porosities were tested as 57% and 45% with a uniform pore distribution. The shrinkage rate was about 10% during sintering process due to binder burning and crystallization shrinkage. The compressive strength of the sintered scaffold was 0.71 ± 0.048 MPa and 2.13 ± 0.054 MPa, respectively, which are consistent with the finite element mechanical analysis simulation results. In conclusion, the layered perforated 45S5 bioglass scaffold shows good mechanical properties and porosity, indicating that it could be a promising candidate for bone tissue engineering.

Achieving enhanced microwave absorption performance based on metal/covalent organic frameworks-derived heterostructures

The high performance “thin, light, wide and strong” pursued by microwave absorbing materials is strongly determined by the structure regulation of materials. Herein, we developed the metal/covalent organic frameworks (MOFs/COFs) heterostructures for enabling multiple interfaces and abundant defect vacancies to enhance impedance matching characteristic and dissipation property. The MOF presents uniform pore distribution, large specific surface area and tunable chemical structures. Furthermore, two kinds of COFs were formed by successively polymerizing based on Schiff-base reaction, and in-situ coated on the MOFs-derived Co/C hybrids to favor rich interfaces. The Co/C@TpPa possesses a minimum reflection loss (RLmin) of −48.7 dB at ultrathin thickness of 1.61 mm. In particular, the RLmin of Co/C@TAPB-PDA is −50.6 dB at 8.8 GHz. Meanwhile, CST simulation was carried out to confirm the microwave absorption capabilities under actual far field conditions. The Radar cross section (RCS) values for Co/C@TpPa and Co/C@TAPB-PDA at 0° scattering angle are reduced to 3.88 dB m2 and -12.23 dB m2 from 7.96 dB m2 (Co/C). It is noted that the RCS values of MOFs/COFs-derived hybrids are less than −10 dB m2 at −90°∼90°. This novel MOFs/COFs open up an avenue for advanced absorbing materials.

Realizing load bearing-heat insulation integration of lightweight porosity-controlled SiC(rGO) bulk ceramics via precursor route for hypersonic vehicles

Realizing integration of admirable load bearing and outstanding heat insulation characteristics of porosity-controlled ceramics for hypersonic vehicles is a great challenge. Herein, an ingenious strategy based on re-pyrolysis process of ball-milling-induced fillers/precursors(pore-forming agents) blends is proposed to prepare porous SiC(rGO) bulk polymer-derived ceramics (PDCs) for thermal protection. During re-pyrolysis, dense integrated β-SiC/SiOxCy/Cfree(rGO) framework, belonging to SiC(rGO)p tightly tied by SiC(rGO) from polycarbosilane-vinyltriethoxysilane-graphene oxide (PCS-VTES-GO, PVG), can be formed to maintain brilliant mechanical properties of products. Meanwhile, good interfacial compatibility of nanocomposite structure within the framework also contributes to load capacity. A uniquely uniform distribution of dentinal tubules-like pores, originated from polystyrene (PS) in SiC(rGO) region, could relax stress at crack tips and ensure good thermal insulation. Particularly, lightweight porous SiC(rGO) bulk PDCs with 10 wt% PS content possess low thermal conductivity (0.25 W·m−1·K−1), excellent fracture toughness (1.96 MPa·m1/2), outstanding hardness (3.58 GPa), optimal compressive strength (51.80 MPa) and good flexural strength (33.86 MPa). Their large-sized molding ability and good high-temperature oxidation resistance were significantly demonstrated by further exploration. Such well-balanced high load bearing and good heat insulation integration nature can be used to make thermal insulators with complex shapes in a facile and economical manner.

Chemically modified surface of silicon nanostructures to enhance hydrogen uptake capabilities

Hydrogen is an active substitute for current commercial fuels as a green energy source. However, the progress toward hydrogen economy is stalled due to a lack of efficient and economical storage systems usually restrained by the material used. Some specific issues still need to improve in recent practical hydrogen storage methods: low surface area, limited capacity to attract gas adsorbate, high-temperature medium for hydrogen desorption, and extreme reactivity towards Oxygen and air. The paper presents a study on the surface modification of silicon nanostructures (SiNSs) synthesized by chemical etching, followed by structure optimization to enhance the hydrogen storage capacity. The standard anodization method prepares porous silicon (PS) while metal-assisted chemical etching fabricates Si and Porous Si nanowires (PSiNWs) on Si and PS substrates. Morphological features like surface area and porous nature were evaluated using SEM, AFM, and BET to interpret the gas-surface interaction. The modified surface area and average roughness of SiNSs increase maximum to 437 m2 g−1 and 501 nm, respectively. The PS shows the highest gas-surface interaction (up to 86.6%) and surface energy due to uniform pore distributions and high surface area. The NMR and FTIR investigate the hydrogen termination on the surface, whereas TG-DSC indicates the desorption of surface hydrides at ∼290 °C. A rank matrix is constructed considering various adsorption-desorption and fabrication parameters to select optimized SiNS, whereas PS is selected as a suitable candidate for hydrogen storage.

Static analysis of porous core functionally graded piezoelectric (PCFGP) sandwich plate resting on the Winkler/Pasternak/Kerr foundation under thermo-electric effect

This paper analyzed static bending and deflection of the porous core functionally graded piezoelectric (PCFGP) sandwich plate resting on the Winkler/Pasternak/ Kerr foundations under thermomechanical and electromechanical loading with different conventional and unconventional boundary conditions. First-order shear deformation theory (FSDT) based displacement field and von Karman geometric nonlinear strain are used for problem formulation. The governing equations of the PCFGP sandwich plate are obtained using Hamilton’s principle. A higher-order finite element method has been employed with a modified iterative Newton-Raphson scheme for solving the governing equations. Convergence and comparison studies demonstrate that the validation of the current model has suitably correct. It has been observed that an increase in the porous exponent in the core part of the sandwich plate reduces the stiffness of the plate with an increase in stress, deflection, and electric potential. The maximum stress, deflection, and electric potential are obtained for porosity dispersion in the Uniform pore distribution (UD) type, while minimum in Un-symmetric pore distribution (USD) type dispersions. Hence, the different embedding porosity in the core part of the sandwich plate plays a significant role in reducing plate structural weight and offering good stability in plate structural bending stiffness.

Analysing the Porosity Distribution in Stone Surfaces by Means of Unilateral NMR after Long-Term Outdoor Weathering

Porosity changes in the near-surface area of sandstones due to long-term weathering can produce deterioration. Therefore, porosity analyses on weathered sandstones are significant for detecting possible influences on the pore structure. Classical methods for determining the porosity and pore size distribution in sandstones can only investigate the entire sample volume. In contrast, in this publication, the porosity was analysed in 0.2 mm steps over a depth of 5 mm by means of single-sided NMR measurements on water-saturated sandstones under vacuum. Evaluations of Obernkirchener and Schleeriether Sandstones that were weathered outdoors in Germany for over 30 years are presented. The results showed that the water content in Vol.-% strongly correlated with the normalised NMR signal. The unweathered sandstones showed a uniform distribution of micro and capillary pores throughout the stone depth. As a result of 30 years of outdoor weathering, changes in the pore structure occurred at the sandstone surface due to weathering down to depths of about 0.6 mm. The porosity of the Schleeriether Sandstone samples, mainly the microporosity, clearly increased in this region. Due to the dominance of capillary pores in the Obernkirchener Sandstone, the changes were not as pronounced, but a shift towards smaller pores in the surface area was observable.

Hierarchically porous glass–ceramics by alkaline activation and crystallization from municipal solid waste incineration ashes

As a hazardous waste, municipal solid waste incineration (MSWI) fly ash poses a serious threat to the environment, and considerable efforts have been made to achieve its harmless treatment. Herein, a novel approach for handling MSWI fly ash has been proposed to prepare porous glass–ceramics by alkali activation–crystallization, which overcomes the difficulty of controlling air bubbles under high temperatures. MSWI bottom ash rich in Al2O3 and SiO2 are co-treating as raw material to develop glass framework structure. The alkali activation mechanism shows that the development of MSWI ashes based basic glass from monomer to silica–aluminate gel under alkaline condition. The influence of H2O2 addition on the morphology and physical properties of porous glass–ceramics were evaluated. Porous glass–ceramics with uniform hierarchical pore structure have been fabricated at 3 mol/L NaOH, a solid loading of 55 wt%, and 1–4 wt.% H2O2, then crystallization treatment at 1150 °C for 2 h, the porosity and the bulk density of which varies from 77.22 to 82.94% and 0.68–0.91 g/cm3 respectively, while their relatively high compressive strength ranges from 1.62 MPa to 3.85 MPa. Attributed to the hierarchical porous structure, uniform distribution of pores and excellent physical properties, porous glass–ceramics has potential applications in construction, filtration, and adsorption materials, providing a convenient and feasible method for the efficient and comprehensive utilization of MSWI ashes.

Achieving high permeability of in-situ formed lightweight Cf/SiC(rGO)px/SiC porous ceramics with improved interfacial compatibility for transpiration cooling

Making lightweight porous ceramics with excellent permeability applied for transpiration cooling is still challenging. Herein, an ingenious fabrication method is proposed to successfully prepare Cf/SiC(rGO)px/SiC porous ceramics possessing low density, high permeability and satisfactory mechanical properties. The introduction of carbon fibers for constructing channels and SiC(rGO)p with three-dimensional (3D) honeycomb cellular net-like structure, could effectively decrease density and improve porosity. Meanwhile, self-supporting porous skeleton, high open porosity and uniform pores distribution contribute to brilliant permeability of the products. Good interfacial compatibility among SiC(rGO)p, carbon fibers and β-SiC/SiOxCy/Cfree matrix, as well as toughening effects of carbon fibers are beneficial for enhancing fracture toughness and compressive strength. Particularly, Cf/SiC(rGO)p0.6/SiC porous ceramics exhibit low density (1.12 g·cm−3), low linear shrinkage (3.22%), especially high permeability (1.36 ×10−7 mm2), satisfactory fracture toughness (1.77 MPa·m1/2), excellent hardness (3.88 GPa) and compressive strength (6.41 MPa), focusing on potential applications as coolant medium in transpiration cooling.

Effects of different hydrocolloids on the water migration, rheological and 3D printing characteristics of β-carotene loaded yam starch-based hydrogel

The effects of guar gum (GG), xanthan gum (XG), carrageenan gum (CG), xanthan-guar gum blend (XG-GG), chitosan (CS), gum arabic (GA) on the water migration, rheological and 3D printing properties of β-carotene loaded yam starch-based hydrogel (BCH) were investigated to expand product form of β-carotene. The results showed that CS addition promoted the migration of weakly bound water to tightly bound water in BCH. Addition of GG, CG, XG-GG, CS and GA enhanced apparent viscosity, G', G'', hardness and gumminess of BCH. CG, XG-GG, CS and GA addition improved printing stability of BCH. The printed objects added with GG and CS displayed smooth lines with fine resolution and higher formability, which showed a more uniform pore distribution and thinner gel skeleton structure. The results of XRD showed that hydrocolloids addition decreased the relative crystallinity of BCH. A combination of physicochemical parameters could be used to discriminate samples through hierarchical cluster analysis.

Bifunctional design of cerium-based metal-organic framework-808 membrane modified separator for polysulfide shuttling and dendrite growth inhibition in lithium-sulfur batteries

Lithium-sulfur battery is perceived as one promising next generation rechargeable battery system, in view of its high theoretical specific capacity and energy density. However, the “shuttle effect” of polysulfides and the uncontrolled growth of lithium dendrites significantly obstruct its practical application. Herein, a bifunctional separator with double-sided modification is developed to simultaneously resolve these issues, which is constructed by growing continuous cerium-based metal-organic framework-808 (Ce-MOF-808) membranes on both sides of the commercial polypropylene (PP) separator through a simple in-situ growth method. On the cathode side, the Ce-MOF-808 membrane can play multiple roles of adsorption, selective sieving and catalytic conversion towards polysulfides, thereby effectively inhibiting their shuttle effect. On the anode side, the highly uniform pore distribution and polar groups of this MOF membrane ensure the fast and homogenous diffusion of lithium ions, endowing a stable lithium nucleation and growth in the cycles. Consequently, the Ce-MOF-808/PP separator exhibits a high initial specific capacity of 954.7 mAh g−1 under 1 C with a very limited capacity fading of 0.025% in 500 cycles, and an outstanding rate capability. Moreover, the separator also ensures the stable cycling of the battery at raised sulfur loading and lean-electrolyte conditions.

Bioactive fluorcanasite reinforced magnesium alloy based porous bio-nanocomposite bone scaffold with controlled degradation

ABSTRACT This study deals with the fabrication of magnesium-alloy-based biodegradable porous bone scaffolds. Selected amounts of calcium, zinc and strontium were incorporated into magnesium-metal-matrix as alloying elements to tune the degradation behaviour, while bioactive fluorcanasite nano-particulates were incorporated to promote bone growth. Green compacts with urea porogen were fabricated using the powder metallurgy route, followed by sintering to achieve the desired porosity in the fabricated samples. The microstructure of the fabricated samples was examined by FE-SEM, coupled with EDS, which revealed uniform distribution of pores and alloying elements. Degradation study of the fabricated bio-nanocomposites revealed the retardation of degradation rate, owing to the incorporation of alloying elements. Hydrogen evolution and pH studies of the immersed samples were also found to be in coherence with the degradation behaviour of the samples. These results, therefore, demonstrated that the fabricated magnesium alloy-based bio-nanocomposite scaffolds have promising potential for bone tissue engineering.

The efficacy of a paeoniflorin-sodium alginate-gelatin skin scaffold for the treatment of diabetic wound: An in vivo study in a rat model

ObjectiveTo investigate the efficacy of a paeoniflorin-sodium alginate (SA)-gelatin skin scaffold for treating diabetic wound in a rat model. MethodsBioinks were prepared using various percentages of paeoniflorin in the total weight of a solution containing SA and gelatin. Skin scaffolds containing 0%, 1%, 3%, 5%, and 10% paeoniflorin were printed using 3D bioprinting technology, and scaffold microstructure was observed with scanning electron microscopy. Skin scaffolds were then used in rats with diabetic wounds. H&E staining, Masson staining, and immunohistochemical staining for IL-1β and CD31 were performed on days 7 and 14. ResultsAll skin scaffolds had a mesh-like structure with uniform pore distribution. Wounds healed well in each group, with the 1% and 3% groups demonstrating the most complete healing. H&E staining showed that skin accessory organs had appeared in each group. On day 7, collagen deposition in the 3% group was higher than in the other groups (P＜0.05), and IL-1β infiltration was lower in the 10% group than in the 3% group (P = 0.002). On day 14, IL-1β infiltration was not significantly different between the 10% and 3% groups (P = 0.078). The CD31 level was higher in the 3% group than in the other groups on days 7 and 14 (P＜0.05). ConclusionA 3% paeoniflorin-SA-gelatin skin scaffold promoted the healing of diabetic wounds in rats. This scaffold promoted collagen deposition and microvascular regeneration and demonstrated anti-inflammatory properties, suggesting that this scaffold type could be used to treat diabetic wounds.

Design and analysis of the mechanical properties of controllable porous scaffolds for bone tissue engineering.

[Formula: see text].