Effect of Pore Morphology and Regional Distribution of Liquid Diffusion Directionality in Nonwoven Fabrics

The effect of pore morphology and regional distribution on liquid diffusion directionality in nonwoven fabrics was investigated in this study.Pore orientation angle(POA) and pore aspect ratio(PAR) were proposed to characterize the pore morphology,and α-region,β-region,and αβ-region were used to describe the characteristics of the pore regional distribution.The directional characteristics of macroscopic diffusion of liquid in nonwoven fabrics were characterized by the indicator of primary diffusion orientation angle(PDOA).Ten kinds of spunlaced nonwoven fabrics were selected.Firstly,the data of pore characteristic indices of each sample were obtained through scanning electron microscope(SEM) and the image processing technology as well,and the pore regional distribution map of each sample was further acquired.Then,the PDOA of each sample was obtained through the droplet method and image processing technology.Based on the data and statistical analysis,it was found that the PDOA of a certain volume of liquid in the nonwoven fabrics presented a significant linear relationship with the average POA of the nonwoven fabrics.And the characteristics of pore distribution affected the directionality of liquid diffusion in the nonwoven fabrics.The samples with a large proportion of α-region and good distribution had prominent liquid diffusion along the direction of laying-up,and the difference in liquid diffusion of the samples was more obvious between the directions of laying-up and vertical laying-up.

Nanoscale pore morphology and distribution of lacustrine shale reservoirs:Examples from the Upper Triassic Yanchang Formation,Ordos Basin

Pore structure plays an important role in the gas storage and flow capacity of shale gas reservoirs. Fieldemission environmental scanning electron microscopy（FE-SEM） in combination with low-pressure carbon dioxide gas adsorption（CO2GA）,nitrogen gas adsorption（N2GA）,and high-pressure mercury intrusion（HPMI） were used to study the nanostructure pore morphology and pore-size distributions（PSDs） of lacustrine shale from the Upper Triassic Yanchang Formation,Ordos Basin. Results show that the pores in the shale reservoirs are generally nanoscale and can be classified into four types： organic,interparticle,intraparticle,and microfracture. The interparticle pores between clay particles and organic-matter pores develop most often,l with pore sizes that vary from several to more than 100 nm. Mercury porosimetry analysis shows total porosities ranging between 1.93 and 7.68%,with a mean value of 5.27%. The BET surface areas as determined by N2 adsorption in the nine samples range from 10 to 20 m2/g and the CO2 equivalent surface areas（2 nm）vary from 18 to 71 m2/g. Together,the HPMI,N2 GA,and CO2 GA curves indicate that the pore volumes are mainly due to pores 100 nm in size. In contrast,however,most of the specific surface areas are provided by the micropores. The total organic carbon（TOC） and clay minerals are the primary controls of the structures of nanoscale pores（especially micropores and mesopores）. Micropores are predominantly determined by the content of the TOC,and mesopores are possibly related to the content of clay minerals,particularly the illite-montmorillonite mixed-layer content.

A New Discovery on the Deformation Behavior of Shale Gas Reservoirs Affecting Pore Morphology in the Juhugeng Coal Mining Area of Qinghai Province, Northwest China

Objective The Juhugeng mining area in Qinghai Province of northwest China has attracted wide attention among geologists for it hosts typical coal measure gases.The shale gas reservoirs were reformed by intensive structural movements during geological periods,

3D printed pore morphology mediates bone marrow stem cell behaviors via RhoA/ROCK2 signaling pathway for accelerating bone regeneration

Bone bionics and structural engineering have sparked a broad interest in optimizing artificial scaffolds for better bone regeneration.However,the mechanism behind scaffold pore morphology-regulated bone regeneration remains unclear,making the structure design of scaffolds for bone repair challenging.To address this issue,we have carefully assessed diverse cell behaviors of bone mesenchymal stem cells(BMSCs)on theβ-tricalcium phosphate(β-TCP)scaffolds with three representative pore morphologies(i.e.,cross column,diamond,and gyroid pore unit,respectively).Among the scaffolds,BMSCs on theβ-TCP scaffold with diamond pore unit(designated as D-scaffold)demonstrated enhanced cytoskeletal forces,elongated nucleus,faster cell mobility,and better osteogenic differentiation potential(for example,the alkaline phosphatase expression level in D-scaffold were 1.5-2 times higher than other groups).RNA-sequencing analysis and signaling pathway intervention revealed that Ras homolog gene family A(RhoA)/Rho-associated kinase-2(ROCK2)has in-depth participated in the pore morphology-mediated BMSCs behaviors,indicating an important role of mechanical signaling transduction in scaffold-cell interactions.Finally,femoral condyle defect repair results showed that D-scaffold could effectively promote endogenous bone regeneration,of which the osteogenesis rate was 1.2-1.8 times higher than the other groups.Overall,this work provides insights into pore morphology-mediated bone regeneration mechanisms for developing novel bioadaptive scaffold designs.

Effects of coal molecular structure and pore morphology on methane adsorption and accumulation mechanism

The adsorption,diffusion,and aggregation of methane from coal are often studied based on slit or carbon nanotube models and isothermal adsorption and thermodynamics theories.However,the pore morphology of the slit model involves a single slit,and the carbon nanotube model does not consider the molecular structure of coal.The difference of the adsorption capacity of coal to methane was determined without considering the external environmental conditions by the molecular structure and pore morphology of coal.The study of methane adsorption by coal under single condition cannot reveal its mechanism.In view of this,elemental analysis,FTIR spectrum,XPS electron energy spectrum,13C NMR,and isothermal adsorption tests were conducted on the semi-anthracite of Changping mine and the anthracite of Sihe Mine in Shanxi Province,China.The grand canonical Monte Carlo(GCMC)and molecular dynamics simulation method was used to establish the coal molecular structure model.By comparing the results with the experimental test results,the accuracy and practicability of the molecular structure model are confirmed.Based on the adsorption potential energy theory and aggregation model,the adsorption force of methane on aromatic ring structure,pyrrole nitrogen structure,aliphatic structure,and oxygen-containing functional group was calculated.The relationship between pore morphology,methane aggregation morphology,and coal molecular structure was revealed.The results show that the adsorption force of coal molecular structure on methane is as follows:aromatic ring structure(1.96 kcal/mol)>pyridine nitrogen(1.41 kcal/mol)>pyrrorole nitrogen(1.05 kcal/mol)>aliphatic structure(0.29 kcal/mol)>oxygen-containing functional group(0.20 kcal/mol).In the long and narrow regular pores of semi-anthracite and anthracite,methane aggregates in clusters at turns and aperture changes,and the adsorption and aggregation positions are mainly determined by the aromatic ring structure,the positions of pyrrole nitrogen and pyridine nitrogen.The degree of aggregation is controlled by the interaction energy and pore morphology.The results pertaining to coal molecular structure and pore morphology on methane adsorption and aggregation location and degree are conducive to the evaluation of the adsorption mechanism of methane in coal.

Collapse behavior and microstructural evolution of loess soils from the Loess Plateau of China

Loess soils are characterized by metastable microstructure, high porosity and water-sensitivity. These soils have always been problematic soils and attracted attention from researchers all over the world. In the present study, three loess soils extracted at various depths from the Loess Plateau of China, i.e. Malan(Q_3), upper Lishi(Q_2~2) and lower Lishi(Q_2~1) loess soils, were studied. Single oedometer-collapse tests were performed on intact loess specimens to investigate the collapse behavior of three loess soils. The microstructure and chemical composition of each loess before and after collapse test were characterized using scanning electron microscopy(i.e. SEM) and energy dispersive spectroscopy(i.e. EDS) techniques. The microstructural evolution due to wetting collapse was interpreted qualitatively and quantitatively in terms of the pore morphology properties. The results suggest that:(1) the collapse potential of each loess may rise again after a round of rise and drop, which could be failure of the new-developed stable structure under quite high vertical pressure. It implies that loess may collapse even if it has collapsed.(2) Q_3, Q_2~2 and Q_2~1 loess have different types of microstructure, namely, granule, aggregate and matrix type of microstructure, respectively.(3) The microstructural evolution due to loading and wetting is observed from a granule type to an aggregate type and finally to a matrix type of structure. The variations in distributions of pore morphology properties indicate that collapse leads to a transformation of large-sized pores into small-sized pores, re-orientation and remolding of soil pores due to particle rearrangement.(4) A porous structure is essential for loess collapse; however, the non-water-stability of bonding agents promotes the occurrence of collapse under the coupling effect of loading and wetting.

Preparation and characterization of porous titanium using space-holder technique

Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompatibility. However, most of the methods used to produce the porous metal can only give limited porosity and uncontrollable pore morphologies. In the present study, a newly developed method of powder metallurgy using the space-holder technique was used to fabricate porous titanium with controllable porosity. The morphological features and mechanical properties of the products were fully investigated. The results show that the porosity is in the range of 55%-75%, and the mean pore size, with an average sphericity of -0.72, is 600 μm. The plateau stresses vary between 10 MPa and 35 MPa. As predicted by the Gibson-Ashby model, the plateau stress decreases with increasing porosity.

Effect of Coated PHB on Properties of Abradable Seal Coating

As pore-forming materials, the coated polyop-hydroxybenzoate（short for PHB） and h-BN can be applied in the preparation of abradable seal coatings at high temperature. The characteristics of coating such as morphology, thermal stability and composition were studied by SEM, EDS and FTIR. The results show that the modified PHB will change the remained carbon amount, porosity and pore morphology of the coating, which can affect the properties of coatings. If the pore is small enough in uniform distribution, the coating with 5 MPa bond strength, 30-55 HR45Y superficial hardness and certain of carbon can be suitable to well abradability.

Experimental on the pore structure characteristics of Longmaxi Formation shale in southern Sichuan Basin,China

In this paper,the pore structure characteristics of shale samples from the Lower Silurian Longmaxi Formation in South of Sichuan Basin of China were investigated by total organic carbon(TOC)content determination,X-ray diffraction(XRD),scanning electron microscope(SEM),low pressure nitrogen adsorption(LPNA)and high pressure mercury injection(HPMI).The fractal dimension of shale samples was calculated based on Frenkel-Halsey-Hill(FHH)model and thermodynamic relation model.The results showed that the major mineral compositions of shales were quartz and clay content.Organic pores,intergranular pores,intragranular pores,microfractures were widely developed in the shale samples,of which organic pores were the most developed.The pore morphology was mainly ink bottle-shaped pores and slit-shaped pores;the pore size distribution of shale samples was complex with multiple distribution peaks,the pore size between 3 and 40 nm occupied the most of storage space.The fractal dimension Dn1 of pores between 2 nm and 10 nm was 2.7177e2.7933,while fractal dimension Dn2 of pores between 10 nm and 50 nm was 2.2439e2.5468.The fractal dimension Dr of macropores calculated by the thermodynamic model was 2.6401e2.7025.