Pore Diameter Research Articles

Preparation of a high performance PES/PES-OH Loose nanofiltration membrane based on reactive porogen

Loose nanofiltration membranes (LNF) have wide applications in the field of precise separation of small organic molecules. However, high separation precision of organic molecules with salts and a high water flux are still the challenges in the commercial applications of LNF membranes. In the current work, polyethersulfone (PES)/hydroxylated polyethersulfone (PES-OH) LNF membranes were synthesized by nonsolvent-induced phase separation (NIPS) based on reactive porogen (butyl dicarbonate, BDC) for the first time. The reactive porogen was decomposed to produce nanobubbles during heat-treated casting solution and phase inversion in HCl coagulation. It was found that the heat-treatment temperature of the casting solution was higher, the viscosity of the solution at 20 °C was higher due to the existence of more nanobubbles from BDC decomposition in the casting solution. Moreover, heat-treatment temperature had decisive impacts on the structure and separation property of the formed LNF membranes as nanobubbles actually acted as pore-forming agents. The HCl coagulation/immersion baths also promoted the BDC decomposition to produce the nanobubbles and improved the transmembrane water flux without sacrificing rejection and separation precision performance. The synthesized LNF membrane had a pore diameter approximately 3.81 nm, with a flux up to 200.2 L·m−2·h−1. Direct Black 38 shows a rejection of > 99 %, whereas NaCl shows a rejection of < 5 %, exhibiting a good separation accuracy and found superior to the separation performance in the literature. This research result has offered a novel approach for the preparation of superior performance LNF membranes, which can be utilized for precise separation.

The effect of phosphoric acid on the properties of activated carbons made from Myrtus communis leaves: Textural characteristics, surface chemistry, and capacity to adsorb methyl orange

In this work, chemical activation was employed to produce activated carbons and assess the impact of phosphoric acid (H3PO4) on their physicochemical properties. Using Myrtus communis Leaves (MC-Leaves) as the precursor and varying H3PO4 impregnation ratios (30 %, 60 %, 100 %, and 150 wt.%). The activation was conducted at 450 °C (10 °C/min) for 1 h in a room atmosphere. The effects of H3PO4 were evaluated through various techniques, including BET surface area analysis, FESEM-EDS imaging, XPS, FT-IR-ATR, Raman spectroscopy, CHNS-(O) elemental analysis, and Methyl orange (MO) adsorption studies. The specific surface area (SSA) and total pore volume increased from 642m2/g to 1237m2/g, total pore volume increased from 0.29cm3/g to 0.97cm3/g, and the mean pore diameter increased from 1.9 nm to 3.2 nm by increasing the impregnation ratio from 30 wt.% to 150 wt.%. The pH(pzc) of MC-ACs exhibited an acidic character, owing to the presence of oxygen-containing functional groups such as hydroxyl, carboxyl, metaphosphate (-PO3-), phosphates, and pyrophosphate groups, as indicated by XPS and FT-IR analysis. At a room temperature of 22 °C and an ideal pH of 2.06, the maximum adsorption capacity (qmax) rose from 46.02±4.63 mg g-1 to 326.54±37.67 mg g-1 as the impregnation ratio increased from 30 wt.% to 150 wt.%. Freundlich isotherm well explained the adsorption equilibrium at 22 °C for all MC-ACs. The effect of temperature illustrates that the adsorption of MO onto MC-AC30 % was endothermic, while the adsorption of MO onto MC-AC150 % was an exothermic. The kinetic study was conducted at 22 °C, when the equilibrium time was at 4hours, and it was a pseudo-second order (PSO) model.

Properties of biocoal briquettes from mesoporous coals and rice husk and their effects on environmental pollution

This work assessed some properties and effects of biocoal briquettes on environmental pollution compared with utilising coal alone. A mixture of coal fines and rice husks was prepared, with cassava starch gel as a binder, before compaction in a briquetting machine and drying with a solar dryer. Samples of the coal fines, rice husk, cassava flour and briquettes were analysed for their elemental and oxide concentrations via an energy-dispersive X-ray fluorescence analyser. The heat fuels were analysed for their thermal behaviour via thermogravimetric analyser (TGA), whereas the specific surface area, pore size and pore volume were determined using a Brunner–Emmett–Teller (BET) analyser. The conversion of the tested coals to biocoal briquettes resulted in a reduction in the level of arsenic in the briquettes. Additionally, the sulphur level decreased from 1.96 to 1.11% in the Okobo-Enjema briquettes and from 1.78 to 0.90% in the Onyeama briquettes. However, the levels of manganese increased from 0.04 to 0.22% in the Okobo-Enjema briquettes and from 0.04 to 0.21% in the Onyeama briquettes. Thermogravimetric analysis at different heating rates revealed that derivative weight loss increased with increasing heating rate, from 4.4% at 10 °C/min to 5.5% at 20 °C/min. BET analysis revealed that the briquettes had larger pore diameters, volumes and specific surface areas than did the coal samples. The coal samples have greater propensity to pollute the environment as the amount of potentially hazardous elements in the samples is greater than in their biocoal briquettes.

Development of mesoporous magnetic nanoparticles supported idarubicin and investigation of apoptotic and cytotoxic effects on cancer cell lines.

Many methods are used for cancer treatment, especially chemotherapy. In addition to the their therapeutic effects, chemotherapeutic drugs also have serious disadvantages, such as not being cell and tissue-specific, causing toxicity in many tissues, and developing drug resistance. Many methods, especially nanocarriers, have been designed to overcome these disadvantages. In this study, we synthesized mesoporous silica iron oxide nanoparticles with different pore diameters and loaded idarubicin (6MFe3O4-NH2-IDA and 35MFe3O4-NH2-IDA). The synthesized molecules were characterized using FT-IR, XRD, and SEM methods. The cytotoxic effects of unbound idarubicin and idarubicin-loaded nanoparticles on MCF7 and HL-60 cell lines were examined by MTT test. Additionally, the expression of anti-apoptotic (Survivin and BCL-2) and apoptotic (BAX, PUMA, and NOXA) genes of the nanoparticles were measured by PCR method. As a result of the analyses, it was seen that nanoparticles with the desired properties and sizes were synthesized. In MTT analysis, it was observed that both nanoparticles dramatically decreased the IC50 value in cell lines. However, the 35MFe3O4-NH2-IDA molecule was found to have lower IC50 values. IC50 values ​​for pristine IDA, 6MFe3O4-NH2, and 35MFe3O4-NH2 at 24h were found to be 3.56, 1.24 and 0.25 µM in the MCF7 cell line and 4.15, 1.16 and 0.34 µM in the HL-60 cell line, respectively. Additionally, apoptotic gene expression increased, and anti-apoptotic gene expression decreased. Our study demonstrates that the effectiveness of idarubicin can be significantly enhanced by its application with mesoporous nanocarriers. This enhancement is attributed to the controlled release of idarubicin from the nanocarrier, which circumvents drug resistance mechanisms, improves drug solubility, and increases the drug-carrying capacity per unit volume due to the porous structure of the carrier. These findings underscore the potential of the synthesized nanocarrier in cancer treatment and provide a clear direction for future research in this field.

Influence of magnesite/limestone addition on the hydration characteristics of ternary slag cement systems

To explore the potential of magnesite adopted as supplementary cementitious material (SCM) in cement industry, the authors of this paper investigated the hydration characteristics of ternary slag cement mixtures containing magnesite or limestone. All cement pastes were formulated with a water-to-binder ratio of 0.4, and a total of 50 % substitution level was applied across the blends, with varying slag and magnesite/limestone contents. Experimental results confirmed that adding limestone to slag cement can promote the hydration of cement clinker through the nucleation effect, while not for magnesite addition. As the substitution ratio of magnesite increased, there was a notable increase in both the critical pore diameter and cumulative pore volume, leading to a continuous decrease in the compressive strength of cement pastes. Compared to limestone-containing blends, the incorporation of magnesite was more beneficial to the compressive strength at 7 and 28 days. Additionally, limestone facilitated the precipitation of hemi- and mono-carboaluminate, whereas no hemicarbonate was observed in mixtures containing magnesite. The addition of magnesite promoted the formation of hydrotalcite-like phase, and the quantitative analysis revealed that the dissolution of magnesite primarily occurred in the first 7 days. The authors believed that the results obtained in this paper proposed new perspectives on utilizing magnesite as SCM in cement industry.

Effects of rock pore and micromorphology on electromagnetic radiation characteristics

Electromagnetic radiation (EMR) is a crucial tool for monitoring and early warning of underground engineering disasters. Investigating the inherent pore characteristics of rocks is essential for a comprehensive understanding of the EMR phenomenon. The EMR was monitored during various types of rock splitting failures. The pore structure and micromorphology of rocks are studied using quantitative methods such as mercury intrusion porosimetry, fractal analysis, and the Gray Level Co-occurrence Matrix (GLCM). Results indicate that the fractal dimension of red sandstone is significantly lower than the other three rocks. The fractal complexity increases sequentially from red sandstone to marble, granite, and limestone. As the fractal dimension decreases, the signal waveform characteristics of the four rocks become more complex before the main fracture, with a significant increase in signals during the compaction and elasticity stages. Higher fractal dimensions lead to a shift in energy and count from elasticity stage to the post-peak stage. The main fracture amplitudes of the four rocks generally exhibited a consistent pattern, following the sequence of granite > marble > limestone > red sandstone. The main fracture amplitude decreases with increasing complexity of the rock's pore micromorphology. Rock pore characteristics affect frequency domain characteristics by influencing rock strength and crack expansion. An increase in the average pore diameter tends to decrease both the main and center frequencies.

Phase evolution and microstructure changes induced by accelerated carbonation in natural hydraulic lime paste with GGBFS addition

Carbonation is a primary factor driving the continuous improvement of the long-term performance of natural hydraulic lime (NHL). This research systematically examines the impact of accelerated carbonation (3 % CO2) on the carbonation depth, phase composition, microstructure, and compressive strength of hardened natural hydraulic lime (NHL) pastes mixed with different amounts of ground granulated blast furnace slag (GGBFS), termed as S-NHL. The findings show that the hydration reaction products of GGBFS and Ca(OH)2 (CH), such as C3AH10, C4AĈH11, and C-S-H, densify the microstructure of S-NHL, resulting in a decrease in carbonation depth with increasing GGBFS content. Accelerated carbonation (AC) promotes the rapid transformation of a significant quantity of CH into calcite in S-NHL, with the carbonation of CH occurring more readily than the carbonation of hydration reaction products. Throughout the AC process, NHL contains only calcite-type calcium carbonate. In contrast, after 28 days of AC, the carbonation of hydration reaction products such as C3AH10 and C-S-H in S-NHL produces a minor amount of aragonite and vaterite. AC continuously reduces the total pore volume and porosity of S-NHL, but the average pore diameter and most probable pore diameter initially decrease and then slightly increase. AC significantly reduces the large pores in S-NHL, ultimately resulting in pores predominantly composed of capillary pores (50–1000 nm). AC facilitates the development of compressive strength in S-NHL paste, with the increase in compressive strength being positively correlated with its CH content.

Calcium Role in Gap Junction Channel Gating: Direct Electrostatic or Calmodulin-Mediated?

The chemical gating of gap junction channels is mediated by cytosolic calcium (Ca2+i) at concentrations ([Ca2+]i) ranging from high nanomolar (nM) to low micromolar (µM) range. Since the proteins of gap junctions, connexins/innexins, lack high-affinity Ca2+-binding sites, most likely gating is mediated by a Ca2+-binding protein, calmodulin (CaM) being the best candidate. Indeed, the role of Ca2+-CaM in gating is well supported by studies that have tested CaM blockers, CaM expression inhibition, testing of CaM mutants, co-localization of CaM and connexins, existence of CaM-binding sites in connexins/innexins, and expression of connexins (Cx) mutants, among others. Based on these data, since 2000, we have published a Ca2+-CaM-cork gating model. Despite convincing evidence for the Ca2+-CaM role in gating, a recent study has proposed an alternative gating model that would involve a direct electrostatic Ca2+-connexin interaction. However, this study, which tested the effect of unphysiologically high [Ca2+]i on the structure of isolated junctions, reported that neither changes in the channel's pore diameter nor connexin conformational changes are present, in spite of exposure of isolated gap junctions to [Ca2+]i as high at the 20 mM. In conclusion, data generated in the past four decades by multiple experimental approaches have clearly demonstrated the direct role of Ca2+-CaM in gap junction channel gating.

FeVO4 nanoparticles for N-Alkylation of acetamides under blue light irradiation: Mechanistic insights and product characterization

This study aimed to synthesize FeVO4 nanoparticles using a wet-chemical approach. The nanoparticles were characterized and confirmed using various techniques. XRD (X-Ray Diffraction) confirmed the triclinic crystal system of the nanoparticles, and the crystallite size was calculated to be 33.5 nm. FE-SEM (Field Emission Scanning Electron) and HR-TEM (High- Resolution Transmission Electron Microscopy) confirmed the spherical nature of FeVO4 with particle size of 41.8 nm. Further SAED (Selected Area Electron Diffraction) confirmed the crystallinity nature of the nanoparticles. Optical studies and EIS (Electrochemical Impedance Spectroscopy) revealed their photocatalytic behavior. The pore volume and diameter of the FeVO4 nanoparticles were 0.024 and 2.102 nm, respectively. The obtained nanoparticles were employed as photocatalysts for the N-alkylation of N-phenyl and N-pyridinyl acetamides under blue LED light. The reaction progressed well in approximately 8–12 h with a yield of 60–90 %. The photocatalytic evaluation was optimized under various conditions and provided with mechanistic investigations. The novel N-alkylated analogues were verified by FT-IR, 1H NMR, 13C NMR, and HRMS. The present work explores a novel approach to N-alkylation using FeVO4 nanoparticles in an effective manner. This may lead to new advancements in FeVO4 based photocatalysts for numerous organic transformations.

Vanillin-crosslinked gelatin-polyvinyl alcohol aerogels: Improved physicochemical properties and antimicrobial activity

Crosslinking is a promising way to fabricate high-performance aerogels. In this study, vanillin (Van) crosslinked gelatin–polyvinyl alcohol (Gel−PVA) aerogels were prepared by vacuum freeze-drying method. The effects of different addition levels of Van on FTIR spectra, microstructures and physicochemical properties including water stability, mechanical properties, thermal stability and thermal insulation properties of aerogels were characterized, and antimicrobial activity of aerogels were validated. The results showed that Van exerted its crosslinking function through Schiff base bonding with Gel and hydrogen bonding with Gel and PVA. Although Van addition caused a slight decline in the thermal insulation performance and the obvious increase in pore diameter of aerogels, moderate Van crosslinking contributed to water stability, mechanical properties and thermal stability of aerogels. Besides, Van crosslinked Gel−PVA aerogel could effectively inhibit the growth of E. coli and B. cinerea. This suggests that the aerogel has promising applications in antimicrobial food packaging.

A study on the impact of ultrasonic-stimulated clean fracturing fluid on the pore structure of medium to high rank coal

The pore structure of coal plays a key role in the effectiveness of gas extraction. Conventional hydraulic fracturing techniques have limited success in modifying the pore structure using clean fracturing fluid (CFF), and the stimulating effects of ultrasonic can enhance the effectiveness of CFF in modifying coal pore structures. To research the effects of ultrasonic stimulation on the pore structure of medium to high-rank coal when using CFF, this study employed mercury intrusion porosimetry (MIP) and low-temperature nitrogen adsorption (LT-N2A) methods to analyze the changes in pore structures after cooperative modification. The results indicate that the pore volume and surface area of medium to high rank coal exhibit an increase and followed by a decrease with increasing Ro,max values, while the average pore diameter and permeability demonstrate a decrease and followed by an increase with Ro,max. Although there are some variations in the results of MIP and LT-N2A analysis for different pore size ranges, the overall findings suggest that ultrasonic stimulation in conjunction with CFF effectively alters the coal pore structure. The most significant improvement was observed in coking coal, where pore volume increased by 22%, pore area decreased by 11% and tortuosity decreased by 47%. The improvement of lean coal is the smallest, the pore volume increases by about 7%, and the surface area decreases by about 14%. It is found that the modification of coal pore volume is mainly concentrated in transition pores and macropores. These research outcomes provide valuable insights into the application of ultrasonic technology in coalbed gas extraction.

Deposition of CdSe Nanocrystals in Highly Porous SiO2 Matrices-In Situ Growth vs. Infiltration Methods.

Embedding quantum dots into porous matrices is a very beneficial approach for generating hybrid nanostructures with unique properties. In this contribution we explore strategies to dope nanoporous SiO2 thin films made by atomic layer deposition and selective wet chemical etching with precise control over pore size with CdSe quantum dots. Two distinct strategies were employed for quantum dot deposition: in situ growth of CdSe nanocrystals within the porous matrix via successive ionic layer adsorption reaction, and infiltration of pre-synthesized quantum dots. To address the impact of pore size, layers with 10 nm and 30 nm maximum pore diameter were used as the matrix. Our results show that though small pores are potentially accessible for the in situ approach, this strategy lacks controllability over the nanocrystal quality and size distribution. To dope layers with high-quality quantum dots with well-defined size distribution and optical properties, infiltration of preformed quantum dots is much more promising. It was observed that due to higher pore volume, 30 nm porous silica shows higher loading after treatment than the 10 nm porous silica matrix. This can be related to a better accessibility of the pores with higher pore size. The amount of infiltrated quantum dots can be influenced via drop-casting of additional solvents on a pre-drop-casted porous matrix as well as via varying the soaking time of a porous matrix in a quantum dot solution. Luminescent quantum dots deposited via this strategy keep their luminescent properties, and the resulting thin films with immobilized quantum dots are suited for integration into optoelectronic devices.

Effect of combined parametric impacts on collapsing the wall quality of WAAM Al5356 component

Even though Wire and Arc Additive Manufacturing (WAAM) of the Al5356 component has garnered attention for making affordable, large-scale components, problems with porosity, humping, and undercut still exist. Therefore, optimising process parameters is crucial to achieving flawless products with consistent layer deposition. Hence in this research, the most important WAAM parameters including travel speed (TS), wire feed speed (WFS), and torch angle (TA), were examined in order to determine how they affected structural integrity while taking into account key responses such as porosity, pore diameter, and tensile strength. The Significance of Criteria Weighted Aggregated Sum Product Assessment (WASPAS) in conjunction with Intercriteria Correlation (CRITIC) was used to investigate the favourable circumstances and confirm that the TA is the most important parameter in the nucleation of pores. The verification studies demonstrate that a 58.2 % reduction in pore diameter results in a 31.8 % increase in tensile strength. An ideal TS and WFS of 65 cm/min and 5 m/min, with a maximum TA of 90°, were found to be the favorable conditions for printing Al5356 wall with a minimum porosity of 0.037 %, enhanced ultimate tensile strength of 278 MPa, and minimum pore diameter of 93 µm, according to the CRITIC associated WASPAS approach. Additionally, using the fractography, the damage process based on the porosity creation was investigated. The optimal parameters for generating a defect-free multi-layer structure were identified, hence enhancing the structure’s suitability for industrial use.

Synthesis and characterization of mesoporous silicate as core and low generation polyamidoamine dendrimer as shell for delivery of 5-fluorouracil from their nano complex

Modern nanomedicine delivers drugs to malfunctioning cells. Several synthetic processes can change the shape, particle size, polydispersity index, surface area, and porosity of mesoporous silica nanoparticles (MSNs). Polyamidoamine (PAMAM) dendrimers are attractive polymers with circular forms, uniform distribution, well-structured branching, internal cavities, and surface terminal groups. The objective of this study is to deliver 5-fluorouracil (5-FU) as passive targeting to carcinogen cells via MSN-PAMAM-G3 nanoparticles. This study involved the direct and adaptable synthesis of MSN as the core vehicle, together with third-generation PAMAM dendrimers as the vehicle shell, with the goal of delivering the 5-FU in a targeted and controllable manner. Tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) are used as templates to make the center nanoparticle. Methyl acrylate (MA) and ethylenediamine (EDA) are monomers that cause the formation of branches in PAMAM. The obtained particles were fully characterized in terms of particle size, polydispersity index, zeta potential, thermal behavior, morphology, pore diameter, pore volume, and specific surface area. The particle size of MSN-PAMAM-G3s showed around 187.71 ± 3.97 nm, with a polydispersity index of 0.17 ± 0.01 and zeta potential of 32.17 ± 1.30 mV. By reducing the ratio of drug to vehicle from 1 to 0.25, a significant increase in the EE% of 5-FU from 21.36 ± 0.70 to 43.12 ± 0.67 was observed. The release of 5-FU from the vehicle (5-FU@MSN and 5-FU@MSN-PAMAM-G3) was shown to be considerably higher in an acidic medium (pH = 5.5) in comparison to a neutral medium (pH = 7.4) (P-value<0.05). Furthermore, in both acidic and neutral conditions, 5-FU release was sustained from the vehicle rather than the 5-FU solution. Our research revealed that the MSN-PAMAM-G3 nanoparticles effectively regulated the encapsulation and release of 5-FU, providing pH-sensitive and sustained medication delivery. It is asserted that this nanocarrier has the potential to effectively deliver 5-FU to cancer cells.

Catalytic Appel Reaction Accessing the Mesoporous Substructure of a Robust and Heterogeneous Polyphosphamide

AbstractPolyphosphamides are normally good flame retardants. Herein a mesoporous polyphosphamide (p‐PPA) with an accessible average pore diameter of &lt;10 nm and a surface area of 1.773 m2/g has been synthesized via condensation of 1,3‐diamino benzene (DAB) and phenyl phosphinic dichloride (PPDC). 31P, 13C CP‐MAS solid‐state NMR, Raman, and X‐ray photoelectron spectroscopic (XPS) characterizations confirm the presence of ‐{PV(O)‐NH}‐ in the repeating unit of the p‐PPA that is further used as a catalytic mediator to perform the Appel reaction i. e., conversion of alcohols to halides with a broad substrate scope and high TON (561). The heterogeneity of p‐PPA allows easy recovery of organic halides and recycling of the catalyst many times. Mesoporous p‐PPA has further given a scope to perform shape‐selective conversion of primary alcohols with linear alkyl chain (1‐dodecanol) while a low conversion for the bulky secondary (cyclo‐hexanol) and tertiary alcohol (tert‐butanol) is observed. Perhaps, the phosphamide units present inside the porous channel are non‐preferable sites for bulkier alcohols, as evident from the competitive experiments. A comparatively less catalytic conversion obtained with an analogous non‐porous n‐PPA, made of tris(2‐aminoethyl)amine (TREN) linker, highlights the role of porosity in p‐PPA to enhance the accessibility of numerous ‐{PV(O)‐NH}‐ reactive units to increase the TON.

Balancing volumetric and gravimetric capacity for hydrogen in supramolecular crystals.

The storage of hydrogen is key to its applications. Developing adsorbent materials with high volumetric and gravimetric storage capacities, both of which are essential for the efficient use of hydrogen as a fuel, is challenging. Here we report a controlled catenation strategy in hydrogen-bonded organic frameworks (RP-H100 and RP-H101) that depends on multiple hydrogen bonds to guide catenation in a point-contact manner, resulting in high volumetric and gravimetric surface areas, robustness and ideal pore diameters (~1.2-1.9 nm) for hydrogen storage. This approach involves assembling nine imidazole-annulated triptycene hexaacids into a secondary hexagonal superstructure containing three open channels through which seven of the hexagons interpenetrate to form a seven-fold catenated superstructure. RP-H101 exhibits high deliverable volumetric (53.7 g l-1) and gravimetric (9.3 wt%) capacities for hydrogen under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar). This work illustrates the virtues of supramolecular crystals as promising candidates for hydrogen storage.

Structure, Properties and Degradation of Self-Assembled Fibrinogen Nanofiber Scaffolds.

Self-assembled fibrinogen nanofibers are promising candidates for skin tissue engineering due to their biocompatibility and ability to mimic the native blood clot architecture. Here, we studied the structure-property relationship and degradation of rehydrated fibrinogen nanofibers prepared by salt-induced self-assembly, focusing on the effect of scaffold layering, cross-linking time and freeze-drying. Optimal fiber stability was achieved with cross-linking by formaldehyde (FA) vapor, while treatment with liquid aldehydes, genipin, EDC, and transglutaminase failed to preserve the nanofibrous architecture upon rehydration. Scaffold layering did not significantly influence the mechanical properties but changed the scaffold architecture, with bulk fiber scaffolds being more compact than layered scaffolds. Freeze-drying maintained the mechanical properties and interconnected pore network with average pore diameters around 20 μm, which will enhance the storage stability of self-assembled fibrinogen scaffolds. Varying cross-linking times altered the scaffold mechanics without affecting the swelling behavior, indicating that scaffold hydration can be controlled independently of the mechanical characteristics. Cross-linking times of 240 min increased scaffold stiffness and decreased elongation, while 30 min resulted in mechanical properties similar to native skin. Cross-linking for 120 min was found to reduce scaffold degradation by various enzymes in comparison to 60 min. Overall, after 35 days of incubation, plasmin and a combination of urokinase and plasminogen exhibited the strongest degradative effect, with nanofibers being more susceptible to enzymatic degradation than planar fibrinogen due to their higher specific surface area. Based on these results, self-assembled fibrinogen fiber scaffolds show great potential for future applications in soft tissue engineering that require controlled structure-function relationships and degradation characteristics.

Fabrication of nanozeolite-Y/chitosan composite based on rice husks for efficient adsorption of methylene blue dye: kinetic and thermodynamic studies

In this work, three solid adsorbents were synthesized, namely, nanozeolite-Y prepared from rice husks ash by a sol-gel method as a green biosource (ZN), chitosan as a cationic biopolymer (CS), and nanozeolite-Y/chitosan composite (CSZ). An eco-friendly composite that consists of chitosan and nanozeolite-Y was used to combine the advantages of nanoparticles with biopolymers two materials to increase the removal % of methylene blue dye. All the synthetized solid adsorbents were investigated using TGA, nitrogen adsorption, SEM, TEM, FTIR, XRD, and zeta potential. The results showed that CSZ particles had a high specific surface area (432.3 m2/g), mesoporosity (with an average pore diameter of 2.59 nm), a smaller TEM particle size (between 28.6 and 60.7 nm), a lot of chemical functional groups, and high thermal stability. CSZ exhibited the maximum adsorption capacity (141.04 mg/g) towards methylene blue. The adsorption nature of methylene blue onto CS and CSZ is endothermic, spontaneous, and a physical adsorption process, while it is exothermic, nonspontaneous, physical adsorption process in the case of ZN, as confirmed by thermodynamic results. Pseudo-second order, Elovich, Dubinin-Radushkevich, Freundlich, Langmuir, Temkin, and adsorption models all fit the MB adsorption well, with correlation coefficients reaching about 0.9997. Nitric acid was found to be the best desorbing agent, with a desorption efficiency of about 99%.

Heterogeneity properties and permeability of shale matrix at nano-scale and micron-scale

Heterogeneity of shale pores at nano-scale and micrometer-scale is of great significance to gas transport properties. In this study, the pore structure of shale samples from lower Silurian Longmaxi Formation in the Sichuan basin is investigated by field emission-scanning electron microscopy (FE-SEM) and x-ray micro-computed tomography (Xμ-CT) technology. Based on fractal theory, the lacunarity is introduced to describe the clustering degree of pores in shale matrix, which can compensate for the limitations of fractal dimension. Combining lacunarity with fractal dimension allows for quantification of subtle differences in pore spatial distribution. For FE-SEM images at nano-scales, the fractal dimension changes in a “U” shape, while lacunarity changes in a “∩” shape. For Xμ-CT images at micrometer-scale, both the fractal dimension and lacunarity change in a logarithmic function. Lacunarity at both nano-scale and micrometer-scale linearly decreases with the increase in fractal dimension. By three-dimensional (3D) pore network modeling analysis, the structure properties of the connected pores, such as the number of pores and throats, pore diameter, pore volume, pore surface, throat length, and coordination number, are quantitatively calculated, and these structure parameters show strong heterogeneity. The average coordination number of the connected pores ranges in 2.92–4.36. This indicates that these pores in shale matrix have poor connectivity. The permeability varies from 0.06 to 0.17 μm2 in two-dimensional (2D) Xμ-CT images but from 3.20 to 34.99 μm2 in a 3D structure. The permeability in the 3D structure is about two order higher in magnitude than that in the 2D Xμ-CT images.

Influence of pore structure on catalytic performance of Cs-Zr/SiO2 catalyst for methyl methacrylate synthesis from methyl propionate and formaldehyde

Methyl methacrylate (MMA) synthesis via aldol condensation of methyl propionate with formaldehyde over Cs-based supported catalysts is intensively investigated, while the effect of their pore structures on catalytic performance still lacks in-depth understanding. Herein, series of Cs-Zr/SiO2 catalysts with different pore structures were prepared for this aldol condensation. The physicochemical characteristics of as-prepared Cs-Zr/SiO2 catalysts were characterized using physical N2 adsorption–desorption isotherms and CO2–/NH3-TPD. In addition, the impact of pore structure on mass transfer, adsorption, and desorption of reactants and products was studied through in situ DRIFTS. The results show that the acid and base site densities elevated with the increasing pore volume. The mass transfer of reactants and products could be promoted with increasing pore size, while their adsorption energies exhibited a volcanic trend. As a result, the Cs-Zr/SiO2 catalysts having average pore diameter of 12–18 nm and acid-base balance was considered as the optimal candidate for MMA production.