Porous Frame Research Articles

Localized Lagrange Multipliers Mixed (u,p) Formulation Applied in Wind Turbine Analysis

Fluid–structure analysis is frequently used to design offshore structures in a large range of engineering applications. In order to install wind turbines from the seashore, it is required that its towers must be attached at the sea floor or a system needs to be developed that allows the turbine to float. Therefore, the objective of this work is to develop a coupled structural finite element analysis using localized Lagrange multipliers (LLM) at idealized monopile wind turbines. This method enables us to model large structures like wind turbine towers submerged in the ocean and determine the influence of the fluid–structure interaction on the dynamic structural response of these equipments. In this work, the mixed formulation [Formula: see text] developed takes into account the condition of irrotationality of the acoustic fluid. The classical LLM method is modified, thus, a new mixed-formulation for the interface frame has fluid pressure and solid displacement as degree of freedom. In other words, a coupling frame is introduced as fictitious porous material with the aim of non-symmetrical coupling between elastic solid and potential fluid. The solution to the non-matching meshes domain problem is also achieved with this methodology by several numerical strategies. The equations of solid and fluid domains are obtained by classical finite element method and their interaction is modeled with Localized Lagrange Multipliers. The solutions of numerical equations are obtained by direct form in a monolithic approach. The new modeling by using a porous material interface frame algorithm is verified through examples.

Reinforced Supramolecular Hydrogels from Attapulgite and Cyclodextrin Pseudopolyrotaxane for Sustained Intra-Articular Drug Delivery.

Injectable hydrogels for nonsteroidal anti-inflammatory drugs' (NSAIDs) delivery to minimize the side effects of NSAIDs and achieve long-term sustained release at the targeted site of synovial joint are attractive for osteoarthritis therapy, but how to improve its mechanical strength remains a challenge. In this work, a kind of 1D natural clay mineral material, attapulgite (ATP), is introduced to a classical cyclodextrin pseudopolyrotaxane (PPR) system to form a reinforced supramolecular hydrogel for sustained release of diclofenac sodium (DS) due to its rigid, rod-like morphology, and unique structure, which has great potential in tissue regeneration, repair, and engineering. Investigation on the interior morphology and rheological property of the obtained hydrogel points out that the ATP distributed in PPR hydrogel plays a role similar to the "reinforcement in concrete" and exhibits a positive effect on improving the mechanical properties of PPR hydrogel by regulating their interior morphology from a randomly distributed style to the well-ordered porous frame structure. The hybrid hydrogels demonstrate good shear-thinning and thixotropic properties, excellent biocompability, and sustained release behavior both in vitro and in vivo. Furthermore, preliminary in vivo treatment in an acute inflammatory rat model reveals that the ATP hybrid hydrogels present sustained anti-inflammatory effect.

High performance of ceramic current collector fabricated at 550 °C through in-situ joining of reduced Mn1.5Co1.5O4 for metal-supported solid oxide fuel cells

A well-connected and high-porosity current collector layer fabricated at a low temperature of 550 °C is designed for metal-supported solid oxide fuel cells (SOFCs). Reduced Mn1.5Co1.5O4 (MCO) powders are used as the binder through the reforming of MCO in the air atmosphere. A high conductivity phase La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) is added to keep the porous frame microstructure and decease the ohmic polarization of the current collector layer. Three current collector layers are prepared: MCO, MCO/LSCF, and LSCF. The working state of each current collector layer in planar SOFC stack is reproduced by special experimental design; the performance is tested in the range of 550–750 °C. The results show that the current collector layer for SOFC is achieved at low temperatures using the reduction-oxidation properties of MCO, and the performance is improved by adding high conductivity phase LSCF. The gas distribution at the cathode side is also simulated for designing a high performance SOFC.

A Hepatocellular Carcinoma Targeting Nanostrategy with Hypoxia-Ameliorating and Photothermal Abilities that, Combined with Immunotherapy, Inhibits Metastasis and Recurrence.

Hepatocellular carcinoma (HCC) is a common and highly malignant tumor that is prone to recurrence and metastasis and has no effective treatment. Unsurprisingly, its prognosis is quite poor; early detection methods and effective low-toxicity treatments are urgently needed. To achieve these goals, we designed a multifunctional, U.S. Food and Drug Administration-approved Prussian blue (PB) nanoparticle (NP) with a porous metal organic frame loaded with sorafenib (SF), conjugated with HCC-specific targeting peptide SP94 and the near-infrared dye cyanine (Cy)5.5. These NPs are amenable to multimodal imaging for dynamic monitoring of their biodistribution and tumor-targeting effects. The SP94-PB-SF-Cy5.5 NPs achieved targeted delivery and controlled SF release and exhibited good photothermal effects. In this strategy, photothermal therapy and SF treatment complement each other, reducing the side effects of SF and achieving a therapeutic effect without local tumor recurrence. In addition, the catalase-like ability of the NPs alleviates tumor hypoxia, and their photothermal effects induce immunogenic cell death, leading to the release of tumor-associated antigens. These effects combine to trigger an antitumor immune response; the NPs also displayed promising inhibitory effects on tumor metastasis and recurrence and produced an abscopal effect and long-term immunological memory when combined with antiprogrammed death-ligand 1 (PD-L1) immunotherapy. These safe, multifunctional NPs represent a valuable treatment option for HCC. In addition, this next-generation treatment model may provide some ideas for the management of HCC and other cancers.

Frame Polymerbetons Based on Fillers of Different Nature

Recently, the frame composite materials have been developed greatly at the production introduction level. The manufacturing technology of these materials is carried out in two stages: first, large aggregates are glued into the frame, and second, the porous frame voids are impregnated with the matrix component. In this article, we studied the various aggregates’ effect on the polymer concrete frame structures properties using epoxy binders. The materials based on the quenched cullet, brickbats, granite and limestone crushed stone, and the polymer granules were considered as large aggregates. The studied properties were the strength and elastic modulus. Quantitative dependences of compressive and bending strength, elastic modulus of frame composites on the aggregate type and other prescription factors are obtained. Using the methods of mathematical experimental planning, the optimal particle size distribution for the composites with grains from quenched cullet was selected. Particular attention should be paid to the possibility of using industrial wastes in polymer concrete compositions: polymer granules, quenched cullet and brickbats. Used glass makes up about 10% of the household waste. Its reuse is usually associated with high capital costs allocated for sorting glass by color, removing stones and other impurities. Glass grinding allows to get a fine-grained filler and aggregate. Strength and deformation characteristics of the matrix compositions, frameworks and composites as a whole are determined.

FEATURES OF CARBON GRAPHITE IMPREGNATION WITH ALUMINUM ALLOY

The process of forming a composite material carbon-graphite-aluminum by impregnating a porous frame AG-1500 with aluminum melt at a temperature of 650С is studied. The redistribution of elements of the impregnating alloy is established. it is shown that the transition of silicon, Nickel, chromium, and iron from the aluminum melt to the «melt - pore surface of carbon graphite» is determined not by the mechanism of chemical localization of conduction electrons, but by the rearrangement of the electronic structure of components during crystallization. In this case, it is possible to change the solubility of the melt elements in aluminum, as a result of the combined action of pressure and temperature on it during the impregnation process.

MORE DETAILSABOUT IMPREGNATION OF CARBON GRAPHITE WITH ALUMINUM

The process of forming a composite material carbon - graphite-aluminum alloy by impregnation of a porous frame AG-1500 is studied. The technology of filling the open porosity of carbon graphite with a metal melt in a device for impregnation in the mode of constant heating of the furnace is described. The method of applying a protective coating to the inner surface of the pores is shown. It is possible to seal the matrix alloy AK12 in the pores of AG-1500 with lead. It is shown that such processing allows to compact the aluminum alloy and modify it due to the comprehensive pressure of the lead alloy.

CoSe2/N-doped carbon porous nanoframe as an anode material for potassium-ion storage

Transition metal selenides (TMS), on account of their relatively high theoretical capacity, unique electrical properties, easy compositing and low cost, are considered to be a candidate anode material for potassium-ion batteries. However, the cycling stability of TMS is unsatisfactory owing to the large intercalation/deintercalation of K ions. Herein, a CoSe2/N-doped carbon porous frame (CoSe2@NC) is successfully synthesized through a simple mixing and sintering approach and displays excellent potassium storage performance. Plentiful C–N bonds in the precursor can induce the formation of homogeneous N-doped carbon matrix and C–N–Co bonds, thus endowing robust structure and high electronic conductivity for superior cycling stability. Therefore, the unique porous nanoframe suppresses volume expansion and provides more diffusion paths for K ions. After 1000 cycles at 50 mA g−1, a high capacity of 311.3 mA h g−1 is acquired. When the current density increases to 500 mA g−1, the CoSe2@NC can still maintain a capacity of 184.5 mA h g−1 after 1000 cycles. The high performance, easy compositing and low cost of the CoSe2@NC make it a favorable material for application in KIBs.

Exploring porous zeolitic imidazolate frame work-8 (ZIF-8) as an efficient filler for high-performance poly(ethyleneoxide)-based solid polymer electrolytes

The incorporation of inorganic fillers into poly(ethyleneoxide)(PEO)-based solid polymer electrolytes (SPEs) is well known as a low-cost and effective method to improve their mechanical and electrochemical properties. Porous zeolitic imidazolate framework-8 (ZIF-8) is firstly used as the filler for PEO-based SPEs in this work. Due to the introduction of ZIF-8, an ionic conductivity of 2.2 × 10−5 S/cm (30 °C) is achieved for the composite SPE, which is one order of magnitude higher than that of the pure PEO. ZIF-8 also accounts for the broader electrochemical stability window and lithium ion transference number (0.36 at 60 °C) of the composite SPE. Moreover, the improved mechanism of ZIF-8 to the composite SPE is investigated by zeta potential and Fourier transform infrared spectrograph characterizations. The stability at the composite SPE/lithium interface is greatly enhanced. The LiFePO4||Li cells using the composite SPE exhibit high capacity and excellent cycling performance at 60 °C, i.e., 85% capacity retention with 111 mA·h/g capacity retained after 350 cycles at 0.5 C. In comparison, the cells using the pure PEO show fast capacity decay to 74 mA·h/g maintaining only 68 capacity. These results indicate that the PEO-based SPEs with ZIF-8 are of great promise for the application in solid-state lithium metal batteries.

Filtration of a highly concentrated suspension in a porous medium

The problems of filtration in porous media are in demand when strengthening foundations and building waterproof walls in rocks. Deep bed filtration of a highly concentrated monodisperse suspension in a homogeneous porous medium with size-exclusion particle retention mechanism is considered. When filtering a suspension in a porous medium, some solid particles get stuck on the porous frame and form a deposit. The concentration of suspended particles injected at the porous medium inlet decreases when moving from inlet to outlet. The mathematical model for a highly concentrated suspension in a porous medium assumes a nonlinear dependence of the deposit growth rate on the concentration of suspended particles. The exact solution to the filtration problem in implicit integral form and the Riemann invariant relating the concentrations of suspended and retained particles are obtained. The problem is solved for a linear filtration function and a general nonlinear concentration function. An asymptotic solution is constructed near the concentrations front of suspended and retained particles. It is shown that the asymptotics is close to the exact solution, the error decreases with increasing order of asymptotic expansions. The asymptotic solution explicitly defines the dependence of the solution on model parameters and can be used to solve the inverse filtration problem.

Individually Encapsulated Frame-in-Frame Structure

A Pt-based nanoframe is a hollow frame with superior catalytic behavior and a metal−organic framework (MOF) is another porous frame with multifunctionalities. Here, we present the combination of th...

FEATURES OF THE DEVELOPMENT OF THE COMPOSITE CARBON GRAPHITE-ALUMINUM ALLOY

The search results of a carbon-graphite-aluminum alloy composite of aluminum carbide Al4C3 and the possibility of controlling the formation of this undesirable phase by organizing a diffusion transition layer are presented. The problem is shown and ways to solve it are proposed for the impregnation of carbon graphite with aluminum or its alloys. For the study, samples were made by impregnating a porous carbon-graphite frame with a cast aluminum alloy.

Ultra-stable Sb confined into N-doped carbon fibers anodes for high-performance potassium-ion batteries

Antimony-based materials with high theoretical capacity are known as promising anodes for potassium-ion batteries (PIBs). However, they still face challenges from the large ionic radius of the K ion, which has sluggish kinetics. Much effort is needed to exploit high-performance electrode materials to satisfy the reversible capacity of PIBs. In this paper, nano Sb confined in N-doped carbon fibers (Sb@CN nanofibers) were successfully prepared through an electrospinning method, which was designed to improve potassium storage performances. Sb@CN nanofibers benefit from the fact that the synergy between the porous nanofiber frame structure and the uniformly distributed Sb nano-components in the carbon matrix can effectively accelerate the ion migration rate and reduce the mechanical stress caused by K+ insertion/extraction, Sb@CN nanofiber electrodes thus exhibited excellent potassium storage performance, especially long cycle stability, as expected. When utilized as a PIB anode, they delivered high reversible capacity of 360.2 mAh g−1 after 200 cycles at 50 mA g−1, and a particularly stable capacity of 212.7 mAh g−1 was also obtained after 1000 cycles even at 5000 mA g−1. Given such outstanding electrochemical performances, this work is expected to provide insight into the development and exploration of advanced alloy-type electrodes for PIBs.

Engineering defect‐enabled 3D porous MoS2/C architectures for high performance lithium‐ion batteries

AbstractDesigning defect‐rich MoS2/C architectures with three‐dimensional (3D) porous frame effectively improve the electrochemical performance of lithium‐ion batteries (LIBs) owing to the improved conductivity and decreased diffusion distance of Li+ ions for lithium storage. Herein, we report a reliable morphology engineering method combining with tunable defects to synthesize defect‐rich MoS2 nanosheets with a few layers entrapped carbon sheath, forming a 3D porous conductive network architecture. The defect‐rich MoS2 nanosheets with expanded interlayers can provide a shortened ion diffusion path, and realize the 3D Li+ diffusion with faster kinetics. A 3D conductive interconnected carbon network is able to improve interparticle conductivity, concurrently maintaining the structural integrity. Benefiting from these intriguing features, the as‐prepared MoS2/C architectures exhibit excellent electrochemical performance: a high reversible capacity of 1163 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles and a high rate capability of 800 mAh g−1 at 5 A g−1. Defect content in MoS2/C architectures can be obtained by changing H2 concentration. Compared with the counterparts with few defects, the defect‐rich MoS2/C architectures show improved electrochemical stability with a superior cycle life, illustrating a highly reversible capacity of 751 mAh g−1 at 0.5 A g−1 after 500 cycles.

Spectroscopic investigations on Se/RE doped sol gel derived silica matrices

Selenium and rare earth ions co-doped inorganic luminescence silica matrices are synthesized through sol gel route. The incorporation of cubic Se quantum dots within the porous silica frame is confirmed from TEM analysis. The successful entrapment of green as well as blue color emitters within the silica frame generates evident luminescence bands in the visible region. Obtained Se/Tb3+ ions doped silica glasses give characteristic sharp emission peaks of terbium ions at 488 nm, 543 nm, 584 nm, 619 nm wavelength under UV excitations. A broad blue emission band from selenium nanodots centered at 421 nm wavelength is observed in the emission spectrum. Colorimetric studies are done with the aid of 1931 chromaticity diagram. CIE indices of the co-doped glasses are found to lie in between the CIE indices of selenium doped silica glasses (0.18, 0.21) and terbium doped silica glasses (0.28, 0.46). For a fixed concentration of Se and terbium in silica glasses, tunable luminescence without shift in peak wavelength is observed under the excitation wavelength of 340 nm to 380 nm. Varying blue to green luminescence intensity ratio (B/G) with the excitation wavelength reveals the possibility of tunable emission of the glassy matrix for their applicability in solid lighting systems.

A linear constitutive model for unsaturated poroelasticity by micromechanical analysis

SummaryThis paper extends the Biot theory of poroelasticity from the saturated to unsaturated case. The Biot phenomenological model uses parameters that are easily observable, such as the deformation of porous frame, total stress, pore pressure, and fluid specific discharge. Such model is preferred for engineering applications. At this macroscopic level, the extension of Biot theory from saturated to unsaturated is straightforward. The constitutive constants, however, are combined properties of solid, pore space, and fluids. In the unsaturated case, the constants are functions of the degree of saturation. Their measurements and tabulation over a range of saturation is generally not feasible for practical applications. In this work, a Biot‐Willis type analysis is performed for the unsaturated case to provide a theory that the bulk material constants can be evaluated using laboratory measurable micromechanical constants under saturated condition, plus a capillary pressure curve (saturation versus suction pressure) typically available for unsaturated porous medium, without the need of measurement at each state of saturation. In particular, it is demonstrated that the surface energy contained in the meniscus interface manifests as a “capillary modulus,” given by the negative inverse slope of the capillary pressure curve. A rigorous analysis based on the thermodynamic variational energy approach is also conducted to lend theoretical support to the phenomenological approach. The presented model can bring a closure to the practical engineering modeling of the deformation of partially saturated porous medium that lacks the information of material constants over the range of saturation.

Functionalization of tissue equivalents based on sodium alginate by human blood plasma

The work is aimed at the development of biodegradable porous frame materials that combine high biocompatibility and possess pro-angiogenic properties, that is, the ability to ensure the active germination of the vessels of the recipient tissue and, possibly, the formation of the de novo vascular bed. Approaches have been developed to create a two-layer matrix structure based on biopolymers - sodium alginate and collagen. The two-layer structure provides the functions of the skin - protective (from external environmental factors) and regenerative - restoration of epithelial tissues of the dermis. The article shows the functionalization of the polymer framework by growth factors — enriched and depleted human blood plasma in different concentrations from 5 to 25 masses. % Methods of functionalizing the polymer matrix were studied and the influence of the inclusion of growth factors on cyto- and biocompatibility, angiogenic properties was established.

Embedded SnO2/Diatomaceous earth composites for fast humidity sensing and controlling properties

A tin oxide/diatomaceous earth (DE) composite was synthesized via the hydrothermal method without using a template or surfactant, and its humidity-sensing and controlling properties were investigated. The SnO2/DE composites have a special embedded structure, in which SnO2 nanoparticles are embedded in the DE porous frame. The optimal composites exhibit short response and recovery times (T = 3 and 8 s, respectively), and their response (S = 35.64) is 11.88 times higher than that of DE (S = 3). Furthermore, the optimal composite C-1:3 was tested to determine its humidity-controlling properties, which revealed that it possessed absorption (27 h, 12.04%) and desorption (5 h, 8.56%) characteristics. Regarding the selectivity, the C-1:3 sensor showed better sensing behavior to humidity than to NO2, NH3 and other gases. These beneficial properties of the composites are due to a honeycomb structure that endows the composite with a large specific surface area for adsorption of H2O molecules and allows charge transfer between the embedded SnO2 nanoparticles. The humidity-sensing mechanism is explained in detail by the Grotthuss proton transfer theory and density functional theory (DFT), which were used together with a Nyquist diagram to analyze the conditions of H2O adsorption. This study demonstrates a novel strategy for designing a material that can rapidly sense and control humidity and provides insights into the application of the composite in sensing and controlling environmental humidity at room temperature.

Development of effective compositions of concrete for the construction of slabs of the roadway of steel concrete span structures

Structural concrete spans of various systems and structures with modular and monolithic roadways were used in the construction of bridges. The article presents the results of a survey of such bridge structures at 3 sites: across the Suju River (Grozny), across the Vologda River (Vologodsk), across the Tsna River in the town of Shatsk, Ryazan Region. Defects and damage to the plates of the carriageway are given. It was found that the most dangerous factors affecting the early failure of the roadway steel-reinforced concrete structures, is used to combat glaze and ice sleet aggressive in relation to reinforced concrete sand-salt mixtures. In addition, the lack of durability of structures due to other factors: vulnerability to carbonization processes; lack of reliability of the mounting joints and connections, the heterogeneity of the plate on the transverse and longitudinal bending. An algorithm for determining the parameters of the safe operation of the elements of bridge structures has been compiled; on the basis of the results of the study, the need to solve two urgent problems has been identified: urgent repairs; development and implementation of new solutions for construction and repair. It is shown that in world practice various types of concretes are developed: powder-activated, frame, etc. as well as protective materials – fine polymer concretes. Provides data on the cyclic strength of these materials, as well as the technology of their installation. In the study of the degree of influence of factors of temperature and humidity of the environment on the amount of short-term creep of polymer concrete, the method of experiment planning with the construction of an orthogonal composition plan was used and a methodical model was obtained relating these values. The main stages of the device of the polymer concrete slab instead of the collapsed one are given. The prospects of polymer-concrete coatings produced by frame technology, consisting in the first stage of gluing the aggregate grains with each other in the form of a future product, and the second, filling the voids of the porous frame with a highly mobile polymer composition is shown.

Silicon and reduced graphene oxide employed as additives to enhance the performances of artificial graphite anode for lithium-ion battery

In order to inherit the advantages of graphite anode and further to improve its capacity for practical applications regarding lithium-ion batteries (LIBs), a three-dimensional (3D) porous artificial graphite/silicon/reduced graphene oxide (G/Si/rGO) aerogel with low silicon content of 4.5 wt.% was fabricated. In this aerogel, artificial graphite (G) acted as a main component, and silicon (Si) nanoparticles and reduced graphene oxide (rGO) were employed as additives. As a result, G/Si/rGO anode was twice as high as the graphite anode regarding the reversible specific capacity after 100 cycling. Furthermore, the G/Si/rGO anode exhibited excellent rate-performance. The enhanced performances of the G/Si/rGO anode were attributed to its structure, in which the compatibility between Si and G was improved by introducing rGO as bridges, conductivity was enhanced and volume stress was released by the constructed 3D porous rGO frame. The systematically reported synthesis strategy may have practical significance for increasing capacity of the current graphite anode with only a small amount of Si.