Porous high-entropy rare-earth phosphate(REPO_(4),RE=La,Sm,Eu,Ce,Pr and Gd)ceramics with excellent thermal insulation performance via pore structure tailoring

Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures.In this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4)(HE(6RE_(1/6))PO_(4))ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents(0–60vol%)on this ceramic properties was systematically investigated.The results show that the porous HE(6RE_(1/6))PO_(4)ceramics with 60vol%starch exhibit the lowest thermal conductivity of 0.061 W·m^(-1)·K^(-1)at room temperature and good pore structure stability with a linear shrinkage of approximately1.67%.Moreover,the effect of large regular spherical pores(>10μm)on its thermal insulation performance was discussed,and an optimal thermal conductivity prediction model was screened.The superior properties of the prepared porous HE(6RE_(1/6))PO_(4)ceramics allow them to be promising insulation materials in the future.

Effects of Pore-forming Agents on Properties of Silicon Carbide Porous Ceramics Prepared from Crystalline Silicon Cutting Waste

SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded using the powder as raw material,the starch and the graphite as pore-forming agents.Effects of additions of different pore-forming agents on the phase composition,microstructures,physical properties,and cold crushing strength of the porous ceramics were investigated.The results show that the main crystalline phases of the synthetic powder areα-S iC(6H-SiC)andβ-SiC(3C-SiC).The phase composition of the porous ceramics includesα-S iC(6H-SiC),β-SiC(3C-SiC),FeSi,quartz and Si2N20.The apparent porosity and closed porosity of the porous ceramics prepared by adding starch are higher,and the cold compressive strength of the porous ceramics added with graphite is higher.As increasing the additions of the starch,the apparent porosity,closed porosity and linear shrinkage ratio of the porous ceramics increase,and the bulk density decreases correspondingly.When 20 mass%starch is added,the apparent porosity,closed porosity,linear shrinkage ratio and cold compressive strength are 57.05%,2.03%,5.10%and 10.20 MPa,respectively.

Properties of SiC Particulate Preforms Based on Different Pore-forming Agents and Bonding Methods for Making SiC/Al Composites

The preforms with high SiC volume fraction （〉50%） were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 ~C and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefits the subsequent infiltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.

Analysis on Pore-Forming Pouring Pile Construction Technology of House Building Project

Compared with the in-place pile, the pore-forming pouring pile is more simple and convenient, with a wider range of construction. In the actual construction process, it is able to pass through complex bottom layer and water layer underground without very high requirements in equipment. The actual bearing capacity of single pile is very strong, so that it can be better to adapt to the actual needs of different scales or the different geological conditions in building. And it has been promoted and used greatly in building construction work [1]. This paper introduces the concept of the pore-forming pouring pile technology, analyzes the pore-forming construction technology and the pile construction technology, then talks about prevention problems of the pore-forming pouring pile construction in House Building Project, at last draws a conclusion that the pore-forming pouring pile technology is the most basic construction technology and is the most effective and convenient way of construction.

Animal secretory endolysosome channel discovery

Secretory pore-forming proteins(PFPs) have been identified in organisms from all kingdoms of life. Our studies with the toad species Bombina maxima found an interaction network among aerolysin family PFPs(af-PFPs) and trefoil factors(TFFs). As a toad af-PFP, Bm ALP1 can be reversibly regulated between active and inactive forms, with its paralog Bm ALP3 acting as a negative regulator. Bm ALP1 interacts with Bm TFF3 to form a cellular active complex called βγ-CAT. This PFP complex is characterized by acting on endocytic pathways and forming pores on endolysosomes, including stimulating cell macropinocytosis. In addition, cell exocytosis can be induced and/or modulated in the presence of βγ-CAT. Depending on cell contexts and surroundings, these effects can facilitate the toad in material uptake and vesicular transport, while maintaining mucosal barrier function as well as immune defense. Based on experimental evidence,we hereby propose a secretory endolysosome channel(SELC) pathway conducted by a secreted PFP in cell endocytic and exocytic systems, with βγ-CAT being the first example of a SELC protein. With essential roles in cell interactions and environmental adaptations, the proposed SELC protein pathway should be conserved in other living organisms.

Preparation and characterization of the porous ceramics from fly ash

Porous ceramics was made from coal fly ash, and the microstructure and other properties were characterized as a function of the amount of the pore-forming agent and firing temperature. The results indicated that the proper sintering temperature for the useful ceramic materials is 1 250℃, and a liquid-phase was involved in the densification process.

Preparation of SiC Porous Ceramics by Crystalline Silicon Cutting Waste

SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30%,40%,by mass) on the phase composition,microstructure,sintering properties,cold compressive strength and thermal shock resistance of as-prepared Si C porous ceramics were investigated. The results show that:( 1) addition of NH4HCO3 remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value( 63. 40%) when 40% NH4HCO3 is added,while the minimum cold compressive strength is 4. 77 MPa;( 2) the specimen with 40% NH4HCO3 has the best thermal shock resistance. The thermal cycling times between1 000 ℃ to room temperature reach 62;( 3) the addition of NH4HCO3 does not remarkably affect the phase composition of the specimens;( 4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.

Mechanical Performance and Micro-structure of Pore Steel Slag Block Prepared by Accelerated Carbonation

Steel slag contains a large amount of calcium silicate,which can react with CO_(2)to generate CaCO_(3)and SiO_(2)colloid,thus steel slag may become a cementitious material with a certain strength.High strength porous steel slag carbonated brick was prepared by adding easily decomposed bicarbonate solid into steel slag as pore-forming agent and then accelerating carbonation.A variety of characterization methods were used to characterize the composition and micro-structure of the samples.The effects of different pore-forming agent dosage and carbonation time on the properties of pore steel slag blocks were discussed.The results show that the addition of ammonia bicarbonate promotes the nucleation and growth of columnar calcite.The strength of steel slag block mixed with 30%pore forming agent can reach 24.8 MPa after 1 day of carbonation,and then the strength development tends to slow down.

Research on One-shot Drilling of CFRP/2A12 Laminated Structure

CFRP/2A12 laminated structure due to the large difference in the properties of the material,very easy to produce defects when making holes,affecting the quality of the workpiece,and thus the connection performance of the two materials.The root cause of the poor quality of CFRP/2A12 laminated structure is the difference in material removal mechanism and the complexity of tool processing conditions.Therefore,this paper analyzes the effects of different process parameters on the pore-forming quality of the laminated material through experiments,reveals the change law of cutting force of the CFRP/2A12 laminated structure,and determines the optimal process parameters.The results show:The axial force generated by the drill when it enters half of CFRP is the largest,which is much larger than the axial force generated when drilling 2A12 aluminum alloy plate,and the thickness of the laminated metal plate is great for drilling.The hole formation sequence of the laminated structure has a significant effect on the cutting force.The axial force when the laminated sequence is CFRP/2A12 is smaller than when the laminated sequence is 2A12/CFRP.

Innovative construction of macroporous–mesoporous structured spherical alumina and its hydrothermal stability

The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of reactants.Maintaining excellent pore structure under strict reaction conditions is of utmost importance.In this work,sphericalγ-Al_(2)O_(3)support with a bimodal pore structure,composed of macropores and mesopores,was successfully synthesized using dodecane as the pore-forming agent through the oil–ammonia column-shaping method.The morphology and internal pore structure of the alumina were found to be influenced by the amount of surfactant added and ultrasound treatment conditions.Notably,when concentration of surfactant was 4‰and ultrasound voltage of 20 V was applied,the resultingγ-Al_(2)O_(3)-4‰-20 displayed a highly concentrated distribution of macropores with an average pore size of 100 nm,resulting in an impressive porosity of 69.21%.In contrast,the untreated sample ofγ-Al_(2)O_(3)-0-0 only exhibited a mesoporous distribution with a porosity of 54.03%.Moreover,after being subjected to a hydrothermal treatment in a high temperature(600°C)and high humidity(water vapor)environment for 120 h,theγ-Al_(2)O_(3)-4‰-20 sample maintained a high BET specific surface area of 170.9 m^(2)g^(−1)and mercury intrusion porosimetry specific surface area of 263.3 m^(2)g^(−1).

State of the art of lightweight aggregates used in lightweight refractories for working lining of high-temperature furnaces

Lightweight refractories for the working lining of high-temperature furnaces play an important role in the smelting of advanced steels and superalloys.To prepare lightweight refractories for the working lining of high-temperature furnaces,the synthesis of lightweight aggregates is the basis.Recently,the research on the synthesis of lightweight aggregates with high service temperature,low thermal conductivity,high strength,and good slag resistance has received widespread attention.The available literature on the synthesis of lightweight aggregates was summarized,including corundum,mullite,mullite-corundum,spinel,corundum-spinel,cordierite,cordierite-mullite,calcium hexaluminate,corundum-calcium hexaluminate,bauxite,magnesia,magnesia-based,and forsterite-based aggregates.Finally,the future development trend of lightweight aggregates was proposed.

Carbon Nanotubes Inhibit the Hemolytic Activity of the Pore-Forming Toxin Pyolysin

Functionalized carbon nanotubes have already demonstrated great biocompatibility and potential for drug delivery.We have synthesized acid oxidized and non-covalently PEGlyated single-walled carbon nanotubes(SWNTs),which were previously prepared for drug delivery purposes,and explored their potential for detoxification in the bloodstream.Our investigations of the binding of SWNTs to a pore-forming toxin pyolysin show that SWNTs prevented toxin-induced pore formation in the cell membrane of human red blood cells.Quantitative hemolysis assay and scanning electron microscopy were used to evaluate the inhibition of hemolytic activity of pyolysin.According to Raman spectroscopy data,human red blood cells,unlike HeLa cells,did not internalize oxidized SWNTs.Molecular modeling and circular dichroism measurements were used to predict the 3-D structure of pyolysin(domain 4)and its interaction with SWNTs.The tryptophan-rich hydrophobic motif in the membrane-binding domain of pyolysin,a common construct in a large family of cholesterol-dependent cytolysins,shows high affinity for SWNTs.

Broad-spectrum and powerful neutralization of bacterial toxins by erythroliposomes with the help of macrophage uptake and degradation

Anti virulence strategy has been considered as one of the most promising approaches to combat drug-rcesistant bacterial infections.Porc-forming toxins(PFTs)are the largest class of bacterial toxins,inficting their virulence ffect through creating pores on the cell membrane.However,curent solutions for eliminating PFTs are mostly designed based on their molecular structure,requiring customized design for different interactions.In the present study,we employed erythroliposome(denoted as RM-PL),a biomimetic platform constructed by artificial lipid membranes and natural erythrocyle membranes,to necutralize different hemolytic PFTs regardless of their molecular structure.When tested with model PFTs,including a-hemolysin,listeriolysin O,and streptolysin O,RM-PL could completely inhibit toxin-induced hemolysis in a concentration-dependent manner.In vivo studies further confirmed that RM-PL.could eficiently neuralize various toxins and save animals'lives without causing damage to 0rgans or tissues.In addition,we explored the underlying mechanisms of this efficient detoxification ability and found that it was mainly macrophages in the spleen and the liver that took up RM-PL-absorbed toxins through a variety of endocytosis pathways and digested them in lysosomes.In summary,the biomimetic RM-PL presented a promising system for broad-spectrum and powerful toxin neutralization with a mech-anism of lysosome-mediaed loxin degradation.

Residue-Specialized Membrane Poration Kinetics of Melittin and Its Variants: Insight from Mechanistic Landscapes

Pore-forming peptides have promising potentials for biomedical uses due to their ability to permeabilize cell membranes.However,to molecularly engineer them for practical applications is still blocked by the poor understanding of the specific roles of individual residues in peptides’activity.Herein,using an advanced computational approach that combines Coarse-Grained molecular dynamics and well-tempered metadynamics,the membrane activities of melittin,a representative pore-forming peptide,and its gain-of-function variants,are characterized from the kinetics and thermodynamics perspectives.Unbiased simulations elucidate the molecular details of peptide-induced membrane poration;during which,some vital intermediate states,including the aggregation and U-shape configuration formation of peptides in the membrane,are observed and further applied as collective variables to construct the multi-dimensional free energy landscapes of the peptide-membrane interactions.Such a combination of kinetic and thermodynamic descriptions of the interaction process provides crucial information of residue-specialized contribution in chain conformation and consequently membrane perforation ability of the peptide.It is found that residues at the kink part(e.g.Thr)determine the chain flexibility and U-shape bending of the peptide,while residues near the C-terminus(e.g.Arg and Lys)are responsible for recruiting neighboring peptides for inter-molecular cooperation;the probable reaction pathway and the poration efficiency are consequently regulated.These results are helpful for a comprehensive understanding of the complicated molecular mechanism of pore-forming peptides and pave the way to rationally design and/or engineer the peptides for practical applications.

Preparation and thermal properties of layered porous carbon nanotube/epoxy resin composite films

A floating-catalyst spray pyrolysis method was used to synthesize carbon nanotube(CNT)thin films.With the use of ammonium chloride as a pore-former and epoxy resin(EP)as an adhesive,CNT/EP composite films with a porous structure were prepared through the post-heat treatment.These films have excellent thermal insulation(0.029–0.048 W·m^−1·K^−1)at the thickness direction as well as a good thermal conductivity(40–60 Wm^−1·K^−1)in the film plane.This study provides a new film material for thermal control systems that demand a good thermal conductivity in the plane but outstanding thermal insulation at the thickness direction.

Phase evolution and properties of novel Al2O3-based poly-hollow microsphere (PHM) ceramics

In this paper, novel Al2O3-based poly-hollow microsphere (PHM) ceramics were prepared using Si3N4 and Al2O3 PHMs as pore-forming agents. The effect of Si3N4 and Al2O3 PHMs with different percentages on properties of Al2O3-based PHM ceramics was investigated. Through adjusting percentage of Al2O3 PHMs, Al2O3-based PHM ceramics with enhanced properties are achieved. X-ray diffraction (XRD) results show that main phases of Al2O3-based PHM ceramics vary from beta-SiAlON (z value increases from 2.9 to 4) to Al2O3 with the increase of percentage of Al2O3 PHMs from 10% to 100%. The different phase compositions result in different properties of Al2O3-based PHM ceramics. With the increase of percentage of Al2O3 PHMs, porosity of Al2O3-based PHM ceramics gradually decreases, while their shrinkage, flexural strength, and fracture toughness firstly decrease and then increase. Using different kinds of ceramic PHMs as pore-forming agents, various novel and high-performance porous ceramics could be prepared via optimizing percentage of ceramic PHMs in the future.