Similar Pore Structure Research Articles

Relationships between reaction products and carbonation performance of alkali-activated slag with similar pore structure

The composition of reaction products is one of the most significant factors affecting the carbonation performance of alkali-activated slag (AAS). However, the relationships between the reaction products and the carbonation performance of AAS have not been established. To address this gap, AAS pastes with different composition and similar pore structure were prepared by adding Al(OH)3 or Mg(OH)2 to evaluate the effect of the composition on the carbonation performance of AAS. Further, in order to gain insight into the influential mechanism of the composition, the principal reaction products in AAS were also synthesized. All produced specimens were tested for carbonation performance, alongside morphological, thermal and chemical characterizations. The results show that among the examined reaction products, the hydrotalcite-like phase (MAH) displayed the strongest carbonation resistance, which was almost immune to the attack of aggressive CO2. By contrast, the calcium aluminate hydrate (CAH) and calcium (alumino) silicate hydrate (C-(A)-S-H) were much more susceptible to the CO2-rich environment. Further, adding Mg(OH)2 to AAS could promote the formation of MAH and in turn, alleviated the carbonation depth of AAS. Whereas, the content of CAH and the A/S (Al2O3/SiO2) ratio of C-(A)-S-H were raised with the increase of Al(OH)3, resulting in a poor carbonation resistance of AAS. Moreover, a multi-factor model with R2 of 0.95 was established to associate the carbonation depth of AAS with the A/S ratio of C-(A)-S-H, the proportion of MAH, and the proportion of CAH. According to the proposed model, the carbonation depth of AAS is believed the most sensitive to the A/S ratio of C-(A)-S-H.

Balsa-based porous carbon composite phase change material with photo-thermal conversion performance for thermal energy storage

Photo-thermal conversion is one of the effective ways to utilize solar energy. Regarding the intermittence and instantaneousness of solar energy, using phase change materials (PCMs) can solve this issue by storing the obtained thermal energy. In this paper, Balsa wood (BW) is treated by delignification and carbonization firstly. Then the carbonized wood (CW) with regular pore structure is introduced into the PCMs as the supporting and photo-thermal conversion media by vacuum impregnation method. The microstructure and thermal properties of the woods and composite PCMs are tested by SEM, POM, MIP, FT-IR, DSC, and TG. The results indicate that the CWs present a similar porous structure to BW, and its porosity is as high as 92.03%. The PCMs are packaged in the porous structure of CWs due to the surface tension and capillary forces, and the maximum effective impregnation ratio of the PCMs into the CW-3 reaches to 85.25 wt%. The phase change temperature and latent heat of CW-3/OP44E are measured as 41 °C and 206.3 J/g, respectively. Moreover, the composite PCMs possess a suitable photo-thermal conversion property, and the photo-thermal conversion efficiency of the composite PCM CW-3/OP44E is 90%. The good thermal stability also indicates its potential application in the thermal energy storage system.

Facile preparation of oxygen-rich porous polymer microspheres from lignin-derived phenols for selective CO2 adsorption and iodine vapor capture

Lignin is a natural O-containing aromatic amorphous polymers from the residues of biorefinery and industrial papermaking, it can derive lots of aromatic phenol chemicals used as industrial raw materials by an efficient depolymerization, and then produce synthetic polymers. Here, we selected six aromatic units from the liquid products of lignin depolymerization, and tried to prepare diversified O-rich hyper-cross-linked polymers (HCPs) by one-pot Friedel-Crafts alkylation reaction for CO2 and iodine vapor capture. HCP1, HCP2, and HCP3 microspheres possessed similar porous structure with Brunauer-Emmett-Teller (BET) surface areas (SBET) of 14.1–20.6 m2/g and high O content (26.34–30.68 wt%), while HCP4, HCP5, and HCP6 were composed of many bulks with 3D networks structure, and showed larger SBET of 15.4–246.9 m2/g and relatively low O content (18.48–26.38 wt%). The results indicated that the chemical position and quantities of substituent groups (methoxy and alkyl) into lignin-derived units had evident impact on their morphology and textural parameters. These HCPs exhibited considerable CO2 uptake (64.1 mg/g) and selectivity (35.2) at 273 K， and high iodine vapor uptake (192.3 wt%). Moreover, the performance analysis implied that the SBET and pore volume of these HCPs had not played the dominated roles in the CO2 and I2 adsorption, while their pore size distribution, O-functional groups, and electron density will be more important for the capture of the both. This study will offer a facile synthesis of O-rich polymer microsphere adsorbents based on the green and sustainable lignin.

Effects of Microwave Heating Paths on Pores and Cracks in Bituminous Coal.

To follow the effect of the microwave heating path on the structure of coal, eight 50 mm diameter, 30 mm long dry coal cores from the same coal seam with similar pore structure characteristics were microwave-treated using 4 pathways. The T2 spectrum, pore-volume, temperature, mass, and visual changes of coal samples were analyzed before and after microwave heating. The microwave heating path affected the macropores and microcracks and the crack development mode. When the same microwave energy was applied, microwave heating on the coal was mainly manifested by the opening of closed pores, before the pyrolysis temperature of the coal was reached. Increasing the energy density caused the water vapor to move from constant pressure expansion to constant volume expansion. This resulted in an exponential growth of the mesopore and macropore volumes. Meanwhile, the micropore volume increased due to the collapse of pore structures. As a result, high-power microwave heating could accelerate the vaporization rate of water. The rapid expansion of water vapor volume brought about a microwave heating effect similar to the “steam explosion”. The resulting local tensile stress enabled the cracks to develop, expand, and connect to others continuously. Thus, it formed a complex crack network leading to the outside of the coal sample.

Incorporation of barium titanate nanoparticles in piezoelectric PVDF membrane

The micro-vibration of piezoelectric polyvinylidene fluoride (PVDF) membranes has been shown to mitigate fouling. To improve the desired piezoelectric properties, piezoelectric barium titanate (BaTiO3) nanoparticles (NPs) were incorporated into PVDF membranes fabricated by non-solvent induced phase separation (NIPS). Due to the high surface energy of BaTiO3 NPs, the nanoparticles tended to agglomerate and were not dispersed uniformly. The silane coupling agent (3-Aminopropyl)triethoxysilane (APTES) with the BaTiO3 NPs showed enhanced compatibility and dispersion in the PVDF membrane. The resulting BaTiO3-PVDF membranes had similar finger-like pore structure as neat PVDF membrane. The dielectric strength, piezoelectric and mechanical properties of BaTiO3-PVDF membranes were enhanced. A linear correlation (R2 = 0.9391) between piezoelectric d33 coefficient and critical flux was observed for poled BaTiO3-PVDF membranes under the influence of electrical AC signal (10 Vpp, 500 Hz) when colloidal silica was used as model foulant. The optimal BaTiO3-PVDF membrane (0.1 wt% BaTiO3, poled and AC applied) showed up to 51% increase in critical flux compared to the neat PVDF membrane (unpoled and no AC applied). Further, extended durations of multiple filtration cycles by up to a factor of 2 to 4 were observed. The membrane operation could be prolonged due to significant reduction in irreversible fouling.

Self-discharge of supercapacitors based on carbon nanosheets with different pore structures

Self-discharge is an important factor to be considered for practical applications of supercapacitors (SCs). While the transport of electrolyte ions largely determines the rate performance of SCs, it also affects their self-discharge rate. In this work, three carbon materials, namely stacking carbon nanosheets (S-CNSs), double-layer carbon nanosheets (DL-CNSs), and flower-like carbon nanosheets (FL-CNSs), with similar pore sizes but different pore structures were synthesized. Due to the different pore structures and correspondingly different ion transport resistances, the rate performances increased from S-CNS, FL-CNS, to DL-CNS SCs. On the other hand, the self-discharge rates increased following the same order – the open circuit voltage dropped from 2.0 to 0.99, 0.74, and 0.53 V after 24 h for S-CNS, FL-CNS, and DL-CNS SCs, respectively. Analysis of the self-discharge processes indicates a combined diffusion-controlled and ohmic leakage self-discharge mechanism and a larger diffusion constant was found for DL-CNS than that of FL-CNS and S-CNS SCs, consistent with their order of self-discharge rates. The results of this work suggest that although fast ion transport is beneficial to the rate performance of SCs, it may also lead to fast self-discharge and limit the duration of energy storage.

A method to predict the resistivity index for tight sandstone reservoirs from nuclear magnetic resonance data

The relationship between water saturation and resistivity index in tight sandstone reservoirs cannot be simply expressed using the Archie equation. This makes the saturation exponent difficult to determine and the water saturation estimation significantly challenging. Based on fractal theory and the Archie equation, a theoretical power function relationship is used to predict the resistivity index using the nuclear magnetic resonance (NMR) transverse relaxation time. In this study, 36 core samples, which were recovered from tight gas sands of the Upper Triassic Xujiahe Formation in the central Sichuan Basin, southwestern China, were studied using laboratory NMR and resistivity experiments to verify the reliability of the proposed relationship. The results of this study show that this theoretical relationship is only effective for core samples that contain similar pore structures and physical properties. To precisely predict the resistivity index from NMR data in formations with complicated pore structures, these 36 core samples were classified into three types based on the pore structure and physical properties. For each type of core sample, the parameters used in this relationship were calibrated, along with the relationships between the water saturation and resistivity index and the saturation exponents. Finally, the predicted saturation exponents and the experimental results were compared and validated using two tight sandstone reservoirs located elsewhere in China. Using this proposed method, tight sandstone reservoir saturation exponents were predicted from NMR data. Combining the existing cementation exponent prediction technique, the indispensable input parameters in the Archie equation were acquired, and water saturations were accurately estimated in tight sandstone reservoirs.

Effects of heating temperature on pore structure evolution of briquette coals

Coal and gas outburst disasters mainly occur in geological structure belts, whose outburst coals are cataclastic, granular, or mylonitic microstructures, and their texture is loose, with mostly broken grain and pieces, so that it they hardly meet the laboratory specimen requirements. Consequently, briquettes are usually prepared at room temperature to study the mechanisms of coal and gas outburst in coal mines. In the present study, we employed a novel method of heating on briquette coal samples to investigate the effect of heating temperature on the strength and pore and fracture structure of briquette coals, and to determine the suitable heating temperature for briquette forming processes. A rock mechanics test system, MTS-815, scanning electron microscopy, nuclear magnetic resonance, and specific surface area and aperture analyzer measurements were used to analyze the mechanical parameters, morphology, and pore size distribution of briquette coal samples at different heating temperatures. The results indicate that the uniaxial compressive strength and elastic modulus of briquette coal first increased and then decreased. The pore size distribution and morphology of the briquette coal samples changed after heating. The smooth intact lamellar shape changed to a rough fractured lamellar shape, and the pores changed from unobvious micropores to observable mesopores and macropores. With an increase in the heating temperature, the transverse relaxation time spectra of the briquette coal samples decreased gradually, and both the porosity of the mesopores and macropores first increased, decreased, and then increased again. The pore diameter distributions of the five tested briquette coal samples had similar pore structures, excluding the sample heated to 600 °C. With an increase in heating temperature, pore volume, specific surface area, and average pore diameter of the briquette coal samples first decreased and then increased. The present study provides a novel method that can be applied in physical simulations aimed at preventing future disasters caused by coal and gas outburst in coal mines.

Preparation of Carbon-Covered Phosphorus-Modified Alumina with Large Pore Size and Adsorption of Rhodamine B

In this study, phosphorus-modified alumina with large pore size was synthesized through a coprecipitation method. The carbon-covered, phosphorus-modified alumina with large pores was prepared by impregnating with glucose and carbonizing to further improve the adsorption of organic dyes. The morphology and structure of these composites were characterized by various analysis methods, and Rhodamine B (RhB) adsorption was also examined in aqueous media. The results showed that the specific surface area and pore size of the phosphorus-modified alumina sample AP7 (prepared with a P/Al molar ratio of 0.07) reached 496.2 m2·g−1 and 21.9 nm, while the specific surface area and pore size of the carbon-covered phosphorus-modified alumina sample CAP7–27 (prepared by using AP7 as a carrier for glucose at a glucose/Al molar ratio of 0.27) reached 435.3 m2·g−1 and 21.2 nm. The adsorption experiment of RhB revealed that CAP7–27 had not only an equilibrium adsorption capacity of 198 mg·g−1, but also an adsorption rate of 162.5 mg·g−1 in 5 min. These superior adsorption effects can be attributed to the similar pore structures of CAP7–27 with those of alumina and the specific properties with those of carbon materials. Finally, the kinetic properties of these composites were also studied, which were found to be consistent with a pseudo-second-order kinetic model and Langmuir model for isothermal adsorption analysis. This study indicates that the prepared nanomaterials are expected to be promising candidates for efficient adsorption of toxic dyes.

Metal–Organic Framework‐Based Ion‐Selective Membranes

AbstractControlling selective ion transport is core for developing novel membrane technologies for high‐efficiency ion separation and energy conversion, and biosensing applications. Metal–organic frameworks (MOFs), an emerging family of porous crystalline materials with permanent porosity, Ångstrom‐sized pores and various functional sites, have been recently found to share some similar pore structures and functionalities analogous to biological ion channels. Extensive efforts have been made to develop new strategies for the construction of MOF‐based ion‐selective membranes for efficient ion separation and energy harvesting. Herein, in this progress report, the rational strategies for fabrication of MOF‐based membranes are introduced first, followed by the analysis of their capabilities for selective ion transport. Then, the applications of MOF‐based ion‐selective membranes for ion separation and energy conversion are discussed in detail. Finally, a summary and some recommendations for future directions in the field are presented.

Cytocompatibility of angiogenesis-promoting acidified silk protein sponge matrices and its effects on wound healing of full-thickness skin defects in rats

Objective: To analyze the mechanism of acidified silk protein sponge matrices and methanolized silk protein sponge matrices in promoting wound healing. Methods: The experimental method was conducted. Acidified silk protein sponge matrices with vascularization ability and methanolized silk protein sponge matrices without vascularization ability were prepared by improved freeze-drying method. General observation was performed. Internal morphology was observed with scanning electron microscope. The secondary structure was observed with X-ray diffractometer (XRD) and infrared spectrometer. Compressive modulus was tested by tensile machine. Two 3-week-old male Sprague-Dawley (SD) rats were used to isolate bone marrow mesenchymal stem cells (BMSCs) cultured in above-mentioned two silk protein sponge matrices, the number of cells was counted under laser scanning confocal microscope after 1, 6 days of culture. Four full-thickness skin defect wounds were made on each one of twelve 8-week-old male SD rats, which were divided into methanolized silk group (24 wounds) and acidified silk group (24 wounds) covered with the corresponding silk protein sponge matrices. On post operation day (POD) 3, 7, 10, and 14, general observation was performed and the remaining wound area was recorded. On POD 3, 7, and 14, the wounds and marginal tissue were collected for hematoxylin-eosin staining (HE) staining and Masson staining to observe growth of new tissue and collagen deposition and CD34 immunohistochemical staining to observe vascularization. Sample number of each index of each group at every time point in animal experiment was 6. Data were statistically analyzed with analysis of variance of factorial design, analysis of variance for repeated measurement, independent-samples t test, and Bonferroni correction. Results: Methanolized silk protein sponge matrices and acidified silk protein sponge matrices had the same composition and similar porous structure, with pore size of 300-500 μm. XRD showed that methanolized silk protein sponge matrices showed a significant crystallization peak, while acidified silk protein sponge matrices was mainly composed of amorphous structure. Infrared spectrometer showed that acidified silk protein sponge matrices appeared a strong absorption peak at 1 650 cm(-1), and the methanolized silk protein sponge matrices appeared a strong absorption peak at 1 630 cm(-1). Compressive modulus of methanolized silk protein sponge matrices was (23.8±1.3) kPa, which was significantly higher than (6.1±0.9) kPa of acidified silk protein sponge matrices (t=19.550, P<0.01). After one day of culture, BMSCs successfully adhered to the two kinds of silk protein sponge matrices, and the cells were not spread. After six days of culture, BMSCs were spread on the two kinds of silk protein sponge matrices, and the number of cells on the acidified silk protein sponge matrices increased significantly. On POD 3, the wounds of the 2 groups did not shrink significantly. On POD 7, the wound area in acidified silk group was significantly smaller than that in methanolized silk group, and new epithelium growth occurred at the wound edge. On POD 14, the wounds of acidified silk group basically healed, and the wounds of methanolized silk group were dry and shrinked significantly. Remaining wound area of acidified silk group on POD 3, 7, 10, and 14 were significantly smaller compared with that in methanolized silk group ( t=7.782, 10.620, 3.707, 6.830, P<0.05 or P<0.01). HE staining, Masson staining, and CD34 immunohistochemical staining showed on POD 3, new tissue growing into silk protein sponge matrices of wounds of acidified silk group was more than that in methanolized silk group, the former group secreted a small amount of collagen, collagen formation was not observed in the latter group, the number of vascular endothelial cells migrated into the matrices were more in the former group than the latter group; on POD 7, the area of new tissue covering matrices hole of wounds of acidified silk group was larger than that in methanolized silk group, collagen in the former group was more than that in the latter group and was evenly distributed, the number of blood vessels in the former group was more than that on POD 3, and the new blood vessels in the latter group were scattered; on POD 14, the new tissue in acidified silk group was similar in structure to normal skin tissue and formed a certain thickness, the new tissue in methanolized silk group basically grew into the matrices, the former group had rich collagen deposition, the latter group had scattered collagen, and blood vessels in the former group distributed uniformly and density of blood vessels was significantly higher than that in the latter group ((55.7±6.0) and (34.1±1.0) pieces/mm(2), respectively, t=9.042, P<0.01). Conclusions: Angiogenesis-promoting acidified silk protein sponge matrices have good cytocompatibility, which can facilitate the rapid formation of vascular network in wound area, providing sufficient blood supply to accelerate the tissue regeneration and collagen deposition, thereby promoting wound healing and improving healing quality, these effects are better than methanolized silk protein sponge matrices.

Alkynyl-Based sp 2 Carbon-Conjugated Covalent Organic Frameworks with Enhanced Uranium Extraction from Seawater by Photoinduced Multiple Effects

Biofouling is a major obstacle to the efficient extraction of uranium from seawater due to the numerous marine microorganisms in the ocean. Herein, we report a novel amidoxime (AO) crystalline cova...

Additive manufacturing of trabecular tantalum scaffolds by laser powder bed fusion: Mechanical property evaluation and porous structure characterization

Porous tantalum scaffolds fabricated by chemical vapor deposition (CVD) have been used commercially for bone tissue reconstruction with excellent treatment efficacy in the past decades. Recently, extensive research has proven that additive manufacturing is a versatile technique for the fabrication of porous materials with well-designed and highly controlled architectures. In this work, we aimed to develop additively manufactured (AM) novel tantalum scaffolds biomimicking trabecular bone by laser powder bed fusion (LPBF) and characterize their mechanical properties and porous structures. Porosity significantly affected the mechanical properties of the AM trabecular tantalum scaffolds. When the porosity decreased from 70% to 60%, the compressive strength, compressive modulus, bending strength, shear modulus, and torque increased to 59.5 ± 0.2 MPa, 3.3 ± 0.3 GPa, 97 ± 4.2 MPa, 6.8 ± 0.3 GPa, 41.2 ± 0.8 MPa, and 91 ± 1.5 N·cm, respectively. At 80% porosity, these values were reduced to 14.2 ± 1 MPa, 1.5 ± 0.4 GPa, 23 ± 0.8 MPa, 1.2 ± 0.2 GPa, 11.2 ± 0.6 MPa, and 27 ± 1.4 N·cm, respectively. The general mechanical properties of AM trabecular tantalum scaffolds were comparable with those of their counterparts fabricated using CVD, which both exhibited excellent ductility and reliability. Industrial computerized tomography analysis showed that open porosity, average pore diameter, largest pore diameter, average strut diameter, largest strut diameter, and pore interconnectivity were 70.1%, 542 μm, 929 μm, 322 μm, 564 μm, and 99.99%, respectively, for AM trabecular tantalum scaffolds (designed porosity of 70%), and 70%, 334 μm, 596 μm, 124 μm, 248 μm, and 99.64%, respectively, for trabecular tantalum scaffolds fabricated using CVD. Their porosity and interconnectivity were identical, whereas the pore diameter and strut diameter exhibited noticeable difference. Scanning electron microscopy (SEM) observations revealed that both methods generated trabecular tantalum scaffolds with a similar porous structure, whereas AM trabecular tantalum scaffolds possessed thicker struts and larger pores. AM and CVD-fabricated trabecular tantalum scaffold struts both demonstrated rough surfaces with nano/microstructures. Our results show that the developed AM trabecular tantalum scaffolds are promising for bone filling and reconstruction applications.

Patterning flat-sheet Poly(vinylidene fluoride) membrane using templated thermally induced phase separation

The presence of surface patterns on separation membranes, when properly designed, can enhance the membrane performance by increasing the active surface area, tuning the surface wettability, and promoting mass transfer in the boundary layer. This work reports a new method of patterning microporous membranes, namely, lithographically templated thermally induced phase separation (lt-TIPS). Templated by surface-patterned elastomeric molds, the TIPS of poly (vinylidene fluoride) (PVDF) and tributyl O-acetylcitrate (ATBC) lead to successful pattern replication onto the PVDF membranes. We systematically examined the TIPS processing conditions, including PVDF/ATBC concentration (20 wt%, 25 wt% and 30 wt%) and quenching temperature (25 °C and 100 °C), on the fidelity of pattern replication, as well as structure and properties of the PVDF membranes. Experimental results show that lower solution concentration and direct quenching to 25 °C lead to higher fidelity of pattern replication. Lower concentration and higher quenching temperature result in membranes with larger pores and higher porosity. In comparison with non-patterned PVDF membranes, the patterned PVDF membranes display similar pore structures, mechanical characteristics and crystallinity. In contrast, the presence of the surface pattern significantly increases the water contact angle and pure water flux, as expected from the increase in active surface area. The work shows that lt-TIPS is an effective method for patterning membranes, complementary to existing imprinting and phase-inversion based methods.

Light sheet fluorescence microscopy applied for in situ membrane fouling characterization: The microscopic events of hydrophilic membrane in resisting DEX fouling

Membrane fouling restricts the wide applications of membrane technology and therefore, it is essential to develop novel analytical techniques to characterize membrane fouling and to further understand the mechanism behind it. In this work, we demonstrate a capability of high-resolution large-scale 3D visualization and quantification of the foulants on/in membranes during fouling process based on light sheet fluorescence microscopy as a noninvasive reproducible optical approach. The adsorption processes of dextran (DEX) on/in two polyvinylidene fluoride membranes with similar pore structure but distinct surface hydrophilicity were clearly observed. For a hydrophilic polyvinylidene fluoride (PVDF) membrane, the diffusion and adsorption of the DEX in membrane matrix were much slower compared to that for a hydrophobic membrane. A concentrated foulant layer was observed in the superficial potion of the hydrophilic membrane matrix while the foulants were observed quickly penetrating across the overall hydrophobic PVDF membrane during a short adsorption process. Both the inner concentrated fouling layer (in membrane superficial portion) and the foulant penetration (in membrane asymmetric structure) presented correlations with membrane fouling irreversibility, which could elucidate the microscopic events of hydrophilic membrane in resisting fouling. In addition, the imaging results could be correlated with the XDLVO analysis, suggesting how the membrane-foulant and foulant-foulant interfacial interactions resulted in a time-dependent membrane fouling process. This work provides a fast, highly-sensitive and noninvasive imaging platform for in situ characterization of membrane fouling evolution and should be useful for a wide range of membrane-based process explorations.

Ethylene polymerization using diatomite as support for zirconocene dichloride/modified methylaluminoxane

In this paper, we report on a zirconocene dichloride/modified methylaluminoxane catalyst system supported on a natural diatomite in order to provide ethylene polymerization catalysts for gas phase or slurry processes. Such natural diatomite support exhibited similar properties of silica-based molecular sieve because of their similar chemical composition and porous structure. The supported catalysts were shown to be highly active and to form flocculent and fibrous polyethylene as proven by scanning electron microscopy. A natural resource diatomite was successfully applied as a support for zirconocene by us. Such catalyst system performed as a silica-based molecular sieve supported zirconocene in the ethylene polymerization. Polyethylene with flocculent and fibrous structure was obtained.

Microstructure, mechanical properties and in vitro biocompatibilities of a novel bionic hydroxyapatite bone scaffold prepared by the addition of boron nitride

Hydroxyapatite (HA) is an ideal bone insert material due to its biocompatibility and osteoconductivity, but the poor mechanical properties limit its wide application in clinical practice. The aim of this work is to fabricate a novel composite that with similar porous structure to cortical bone and high mechanical properties by the addition of boron nitride (BN) and sintered in air at 1250 °C for 40 min. In mechanical properties, the maximum flexural strength, elastic modulus and fracture toughness are 94.04 MPa, 69.46 GPa and 1.16 MPa m1/2, respectively, which are improved by 20.56%, 12.87% and 8.41%, respectively. In the microscopy of surface and fracture surface, the porous structure similar to cortical bone is observed. There are microscale and nanoscale pores, and the pores present an interconnected structure. In vitro biocompatibility assessment, the addition of BN and its reaction product have no adverse effect on osteoblast viability, which even promotes osteogenic differentiation and mineralization.

Cubic-like PtCuRu Nanocrystals with High Activity and Stability for Methanol Electro-oxidation.

Porous cubic-like PtCu and PtCuRu nanocrystals, which had a similar porous three-dimensional structure, were successfully prepared via the one-pot method. During the growth of the nanocrystals, cetyltrimethylammonium chloride and ascorbic acid were employed as the structure director and assistant reducing agent, respectively. The structure and possible formation of the nanocrystals were investigated. It is worth mentioning that the PtCuRu nanocrystals demonstrated a much better methanol electro-oxidation ability and ultrahigh stability, which displayed 3.4- and 3-fold higher specific and mass activity, respectively, than the commercial Pt/C. The advantage of PtCuRu nanocrystals was possibly ascribed to the synergistic effect of Cu and the porous structure and, more importantly, the presence of Ru that could more efficiently eliminate the harmful intermediates.

Enhanced Proton Conductivity of Imidazole-Doped Thiophene-Based Covalent Organic Frameworks via Subtle Hydrogen Bonding Modulation.

Anhydrous proton-conductive materials have attracted great attention in recent years. Doping imidazole as a proton carrier in porous materials, especially pure organic crystalline covalent organic frameworks (COFs), is a promising solution. However, the influence of the hydrogen donor ability of imine functional groups inCOFs on the proton conduction has largely been unexplored. Herein, a series of iso-reticular thiophene-based COFs has been synthesized with a similar pore structure and surface area. Different amounts of imidazole were infiltrated to the COFs by vapor diffusion in a highly controlled manner. The introduction of thiophene rings increases the hydrogen bonding donation ability of the imine linker, which resulted in an enhanced proton conductivity of the imidazole-doped COFs by one order of magnitude. The formation of hydrogen bonding between the imine group and imidazole was demonstrated by Fourier transform infrared spectroscopy and density functional theory calculations.

Correlation Between Ultrasonic Pulse Velocity and Thermal Conductivity of Cement-Based Composites

The thermal conductivity of construction materials is among the main factors influencing the thermal performance of buildings. This property is, thus, extensively demanded for design purposes. The thermal conductivity is especially related to the pore system and the composition of cement-based composites, the same factors that affect their Ultrasonic Pulse Velocity (UPV). In this sense, the present work evaluates the correlation between thermal conductivity and UPV. To this purpose, mortar specimens were investigated, with varying mix proportions, fine aggregate types, and dosages of air-entraining admixture. A satisfactory determination coefficient (R2 > 0.9) was obtained between thermal conductivity and UPV of the mortars when they were grouped under similar components and pore structure. It was observed that the pore system of the mortars tested is more influential to the UPV than their overall porosity. In this sense, a better correlation was found between UPV and thermal conductivity than between thermal conductivity and specific gravity. Additionally, the fine aggregate type presents a significant impact—not only due to its chemical and mineralogical properties but also as a result of the morphology that each aggregate generates within the matrix. In conclusion, this technique potentially presents high applicability to the thermal characterisation of cement-based composites.