Good Porous Structure Research Articles

Utilization of cocoa pod husk waste biomass for post-combustion CO2 adsorption

Biomass-derived activated carbon for carbon dioxide (CO2) post-combustion has been drawing attention because they are cost-effective and environment-friendly. In this study, activated carbon was prepared from cocoa pod husk waste (COP) biomass for CO2 adsorption. The COP was pyrolyzed and activated using potassium hydroxide (KOH). The activated carbon prepared was characterized using scanning electron microscopy (SEM), Scanning Electron Microscopy- Energy Dispersive Spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis. The performance of the activated carbons prepared for CO2 was evaluated using a CO2 gas analyzer. Optimization of the adsorption process of CO2 was carried out by varying some important variables affecting the adsorption process. Results showed activated carbon prepared has a good pore structure with high carbon content that supported CO2 adsorption. The Freundlich model provided the best fit with the experimental data while data fitted well to pseudo-second-order kinetics with an adsorption capacity of 6.5 mg/g. The optimal condition for CO2 adsorption, was an adsorption time of 1 min, a Carbonization temperature of 700 °C, and Bed height of 5 cm, and % CO2 removal of 99.5%. The study revealed (COP) biomass as a suitable activated carbon precursor for CO2 capture.

Preparation and characterization of high performance super activated carbon based on coupled coal/sargassum precursors

High electrochemical performance supercapacitors require activated carbon with high specific surface area, suitable pore size distribution and surface properties, and high electrical conductivity as electrode materials, whereas there exists a trade-off relationship between specific surface area and electrical conductivity, which is not well met by a single type of carbon source. To solve this problem, the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution, followed by carbonization and KOH activation. The effects of mixing mass ratio and activation temperature on the prepared activated carbon (AC) are investigated using single factor experimental method. The experimental results show that AC1/3-800 has abundant micropore and mesopore content, good pore structure connectivity, high electrical conductivity and good wettability, and superior electrochemical properties compared with other activated carbons prepared in this experiment. Its total specific surface area is up to 2098.5 m2·g–1, the pore volume is up to 1.33 cm3·g–1, the content of mespores with diameter of 6–8 nm is significantly increased, and the pore size distribution is wide and uniform. When the current density increases from 0.1 A·g–1 to 10 A·g–1, the gravimetric capacitance decreases from 219 F·g–1 to 186 F·g–1 with a capacitance retention of 84.9%, the equivalent series resistance is very small, and the rate performance and reversibility of charging and discharging have also been excellent.

Novel biphasic high-entropy ceramic aerogels and their fiber composites with low thermal conductivity, high thermal stability and significant thermal insulation property

A novel biphasic high-entropy (Y0.2Ho0.2Tm0.2Yb0.2Lu0.2)2SiO5/(Y0.2Ho0.2Tm0.2Yb0.2Lu0.2)2Zr2O7 ceramic aerogel (BP-HEZSA) was prepared using formamide/sol-gel, supercritical CO2 drying and combined with a heat treatment process. The results indicate that BP-HEZSA exhibits a biphasic high-entropy structure at 1200 °C, and it maintained its stability at 1400 °C while demonstrating a homogeneous distribution of elements. BP-HEZSA exhibited nanoscale fine grains (with a size range of 18.82 nm to 27.62 nm), high BET specific surface area (16.24 m2·g−1), and good pore structure, all of which were controlled by the thermal treatment temperature. BP-HEZSA had low room temperature thermal conductivity and high structural and phase thermal stability at high temperatures. Furthermore, the applicability of the aerogel was improved by compounding with aluminosilicate fibers. The composites exhibited low density and low thermal conductivities (0.04–0.14 W·m−1K−1). Butane blowtorch testing confirmed superior thermal insulation in the composites, meeting demands for high-temperature resistance in the advanced nanostructured materials.

Development of magnesium hydroxide-doped nanofibrous spheres for repairing infected skin wounds

The healing of skin wounds is a continuous and coordinated process, typically accompanied by microbial colonization and growth. This may result in wound infection and subsequent delay in wound healing. Therefore, it is of particular importance to inhibit the growth of microorganisms in the wound environment. In this study, magnesium hydroxide-doped polycaprolactone (PCL/MH) nanofibrous spheres were fabricated by electrospinning and electrospray techniques to investigate their effects on infected wound healing. The prepared PCL/MH nanofibrous spheres had good porous structure and biocompatibility, providing a favorable environment for the delivery and proliferation of adipose stem cells. The incorporation of MH significantly enhanced the antimicrobial properties of the spheres, in particular, the inhibition of the growth of S. aureus and E. coli. We showed that such PCL/MH nanofibrous spheres had good antimicrobial properties and effectively promoted the regeneration of infected wound tissues, which provided a new idea for the clinical treatment of infected wounds.

Water-triggered shape memory cellulose / sodium alginate / montmorillonite composite sponges for rapid hemostasis

Uncontrollable bleeding caused by severe trauma is life-threatening. Therefore, it is of great significance to develop hemostatic materials that meet the rapid hemostasis of wounds. In this study, a water-triggered shape memory carboxylated cellulose nanofiber/sodium alginate/montmorillonite (CNSAMMTCa) composite hemostatic sponge was prepared, which can promote coagulation by concentrating the blood and activating intrinsic pathway. The anisotropic three-dimensional porous structure formed by directional freeze-drying technology improved the performance of composite sponges which showed good prospects in rapid hemostasis. The results showed that CNSAMMTCa composite sponge had good porous structure, water absorption ability, cytocompatibility and blood cell aggregation capacity. Simultaneously, we confirmed that CNSA3MMT2Ca has best coagulation performance in the mouse censored bleeding model and liver rupture bleeding model. Therefore, CNSAMMTCa composite hemostatic sponge is a safe and efficient rapid hemostatic material which is expected to become an alternative material for clinical hemostatic materials.

Catalytic pyrolysis characteristics of polystyrene by biomass char-supported nanocatalysts

Plastics originate from the synthesis of chemical products, and the regeneration of chemical products from waste plastics through catalytic pyrolysis helps to reduce the dependence on fossil resources and improve the treatment of waste, which is an important aspect of current sustainable social development. In this study, metasequoia was used as a biomass precursor and three porous char-supported nanocatalysts (Fe-MEC, Ni-MEC, and Co-MEC) were synthesized via a simple and feasible microwave heating method, which were then used as catalysts for the preparation of high-quality liquid oil from polystyrene powder via an ex-situ catalytic pyrolysis method. The results indicate that Fe-MEC, Ni-MEC, and Co-MEC possessed good pore structures due to the microwave-heating and catalytic effect of these metals, and metal nanoparticles are generated and uniformly anchored on the matrix of the char support. Using these catalysts, the yield of liquid product from polystyrene pyrolysis decreased slightly, while the gas yield increased slightly. Fe-MEC catalysis reached the highest liquid yield of 91% among the three catalysts. The catalysts can improve the yield of a series of high-value liquid products such as toluene, ethylbenzene, and α-methyl styrene. The catalysts also exhibited excellent cycle stability, and carbon nanotubes were formed which are less prone to deactivation.

In Situ Ca‐ and Mg‐ Codoped Biochar Derived from Tobacco Stem for Phosphate Adsorption and Desorption

AbstractPhosphorus is an important element for plant growth. The efficient use and recovery of phosphorus is crucial due to limited phosphate resource reserves. This study explored the potential application of an in situ Ca and Mg co‐doped biochar derived from tobacco stem to reclaim and reuse phosphate from aqueous solutions. We performed various batch adsorption experiments and industrial analysis based on different parameters. The findings indicate that biochar prepared using the raw material particle size range of 0.85–2 mm and pyrolyzed at 800 °C presented good pore structure and specific surface area. Ca and Mg elements in biochar exhibited great influence on its phosphate adsorption property. The maximum phosphate adsorption capacity of the tobacco stem‐based biochar was 54.66 mg/g, and the experimental data agreed with the Langmuir equation, suggesting monolayer adsorption. The adsorption process conformed to the pseudo‐second‐order kinetic equation, indicating that chemisorption was the dominant adsorption process and that the adsorption was controlled by intra‐particle diffusion. Furthermore, phosphate adsorbed on tobacco stem‐based in situ Ca and Mg co‐doped biochar was released under acidic, alkaline, and neutral conditions. Therefore, in situ Ca and Mg co‐doped biochar prepared from tobacco stems is a potential environmentally friendly and low‐cost adsorbent for phosphorus recovery.

Effect of Different Drying Methods on the Quality of Oudemansiella raphanipes.

In this study, we used fresh Oudemansiella raphanipes as raw materials and pre-treated through hot air drying (HD), infrared radiation drying (ID), and vacuum freeze drying (VD) to investigate the effects of different drying methods on the rehydration rate, appearance quality, microstructure, and volatile flavor components of the dried products, as well as to determine the physicochemical properties and bioactivities of the polysaccharides in the dried O. raphanipes. The results showed that the VD O. raphanipes had the highest rehydration rate and the least shrinkage in appearance, and it better maintained the original color of the gills, but their aroma was not as strong as that of the HD samples. The scanning electron microscopy results indicate that VD maintains a good porous structure in the tissue, while HD and ID exhibit varying degrees of shrinkage and collapse. Seventy-five common volatile substances were detected in the three dried samples, mainly alkanes, alcohols, and esters. The polysaccharides (PS-H, PS-I, and PS-V) extracted from the dried samples of these three species of O. raphanipes had similar infrared spectral features, indicating that their structures are basically consistent. The highest yield was obtained for PS-V, and the polysaccharide content and glucuronic acid content of PS-I were higher than those of the remaining two polysaccharides. In addition, PS-V also showed better antioxidant activity and inhibitory activity against α-glucosidase as well as α-amylase. In conclusion, among the above three drying methods, the quality of O. raphanipes obtained by vacuum freeze drying is the best, and this experiment provides a theoretical basis for the selection of drying methods for O. raphanipes.

3D Bioprinting-Based Dopamine-Coupled Flexible Material for Nasal Cartilage Repair.

Since 3D printing can be used to design implants according to the specific conditions of patients, it has become an emerging technology in tissue engineering and regenerative medicine. How to improve the mechanical, elastic and adhesion properties of 3D-printed photocrosslinked hydrogels is the focus of cartilage tissue repair and reconstruction research. We established a strategy for toughening hydrogels by mixing GelMA-DOPA (GD), which is prepared by coupling dopamine (DA) with GelMA, with HAMA, bacterial cellulose (BC) to produce composite hydrogels (HB-GD). HB-GD hydrogel scaffolds were characterized in vitro by scanning electron microscopy (SEM), Young's modulus, swelling property and rheological property tests. And biocompatibility and chondrogenic ability were tested by live/dead staining, DNA quantitative analysis and immunofluorescence staining. Combined with 3D bioprinting technology, mouse chondrocytes (ADTC5) were added to form a biological chain to construct an in vitro model, and the feasibility of the model for nasal cartilage regeneration was verified by cytology evaluation. With the increase of GD concentration, the toughness of the composite hydrogel increased (47.0 ± 2.7 kPa (HB-5GD)-158 ± 3.2 kPa (HB-20GD)), and it had excellent swelling properties, rheological properties and printing properties. The HB-GD composite hydrogel promoted the proliferation and differentiation of ATDC5. Cells in 3D printed scaffolds had higher survival rates (> 95%) and better protein expression than the encapsulated cultures. The HB-10GD hydrogel can be made into a porous scaffold with precise shape, good internal pore structure, high mechanical strength and good swelling rate through extrusion 3D printing. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Effects of metal-coupled exogenous nitrogen on the performance of supercapacitors based on biomass carbon materials

Supercapacitors offer great potentials in the field of energy storage due to their high power density, high charge and discharge efficiency, and excellent cycle performance. The relatively low specific capacitance limits their further development and application. Insertion of heteroatoms is one of the most effective strategies to improve the specific capacitance. In this study, different metal salts (Fe/Co/Ni)-coupled N-doped biochar materials, MS-X-N (X represents the metal element), were produced from cornstalk as carbon source and urea as nitrogen source by the chemical activation method to explore the effect of metal(Fe/Co/Ni)- N coupling on the physicochemical and electrochemical properties of biochar. The prepared samples had good pore structure and their specific surface areas were between 1500 and 1800 m 2/g. The doping elements were all successfully inserted into the biochar with the metal content of 0.3%∼0.9% and N content of 2.5%∼4.0%. In the electrochemical test of biochar with a current density of 0.5A/g, MS-X-N samples showed specific capacitance of 180–450 F/g with MS-Co-N giving the best result. Under the combined influence of Co and N, the capacitance of biochar was significantly enhanced. At the current density of 0.5 A/g, the MS-Co-N sample had a specific capacitance 443.94 F/g, an energy density was 15.41 Wh/kg, and a power density was 250.19 W/kg. The findings of research provides a new avenue for the fabrication of high-efficiency supercapacitors.

Homogenization spin coating strategy for synthesizing IM-BTO photocatalytic membrane aims to tetracycline selectively degradation

Photocatalytic membrane technology is a promising technology for advanced water treatment. However, as a simple, fast, and stable spin coating method for photocatalytic membrane preparation, the spin coating solution often used in spin coating can cause the pore plugging on the membrane surface and encapsulates photocatalysts, which seriously affects the flux of the membrane and the exposure of the photocatalytic active site. Here, this work adopted a homogenization spin coating strategy, using polyvinylidene difluoride (PVDF) solution as the spin coating solution to prepare the highly exposed imprinted bismuth titanate porous photocatalytic membrane (IM-BTOM). Due to the same composition of PVDF solution as the PVDF substrate membrane, IM-BTOM basically retained the good porous structure of the membrane. The homogenization spin coating strategy not only endowed IM-BTOM with high flux (4545.45 L m-2h−1 bar−1), but also prevented the encapsulation of IM-BTO powder materials, fully exposing the photocatalytic active sites, thereby obtaining better photocatalytic ability and selectivity. The degradation rate of tetracycline with IM-BTOM was nearly three times that with the conventional cellulose acetate spin coating membrane. Meanwhile, the existence of imprinting cavities also endowed IM-BTOM with high selectivity for the target pollutant, with a selectivity coefficient of up to 2.66. This work provides a new idea for preparing high-efficient photocatalytic membrane by spin coating.

3D printed polycaprolactone/β-tricalcium phosphate/carbon nanotube composite – Physical properties and biocompatibility

Three-dimensional (3D) printing is a bio-fabrication technique used to process tissue-engineered scaffolds for bone repair and remodeling. Polycaprolactone (PCL)/β-tricalcium phosphate (TCP) has been used as a base and osteoconductive biomaterial for bone tissue engineering in the past decades. The current study reveals the fabrication of a polycaprolactone (PCL)/β-tricalcium phosphate (TCP) scaffold by incorporating carbon nanotubes (CNT) via 3D printing. The physical properties and cytocompatibility of a new type of tissue engineering composite from polycaprolactone/β-tri-calcium phosphate/carbon nanotubes were investigated, and it was an absorbable scaffold prepared via furnace deposition 3D printing technology. The scaffold was designed with CAD software, and the composite material was fabricated via 3D printing. The printed composite material was tested for mechanical strength, scanning electron microscope (SEM) analysis, porosity calculation, systemic toxicity test, hemolysis rate determination, and effect on the proliferation of rat adipose-derived stem cells cultured in vitro. A composite scaffold with a length of 15 mm, width of 10 mm, and height of 5 mm was manufactured through CAD software drawing and 3D printing technology. Scanning electron microscopy measurements and analysis of the internal pore size of the stent are appropriate; the pores are interconnected, and the mechanical strength matches the strength of human cancellous bone. The calculated porosity of the stent was >60%, non-toxic, and non-hemolytic. The proliferation activity of the ADSC co-cultured with different scaffold materials was as follows: polycaprolactone/β-tricalcium phosphate/0.2% carbon nanotube scaffolds > polycaprolactone/β-tricalcium phosphate/0.1% carbon nanotube scaffolds > polycaprolactone/β-tricalcium phosphate/0.3% carbon nanotube scaffolds > polycaprolactone/β-tricalcium phosphate scaffolds (P < 0.05). The results showed that polycaprolactone/β-tricalcium phosphate/0.2% carbon nanotube scaffolds promoted the adhesion and proliferation of ADSC. The combination of 3D printing technology and CAD software can be used to print personalized composite stents, which have the characteristics of repeatability, high precision, and low cost. Through 3D printing technology, combining a variety of materials with each other can provide the greatest advantages of materials. The waste of resources was avoided. The prepared polycaprolactone/β-tri-calcium phosphate/0.2% carbon nanotube scaffold has a good pore structure and mechanical properties that mimic human cancellous bone, is non-toxic and non-hemolytic, and is effective in promoting ADSC proliferation in vitro. Given this correspondence, 3D printed scaffold shows good biocompatibility and strength, and the fabrication method provides a proof of concept for developing scaffolds for bone tissue engineering applications.

Adsorption Performance and Mechanism of Oxytetracycline in Water by KOH Modified Biochar Derived from Corn Straw

The pollution control of tetracycline antibiotics in the environment has become a hot topic, and biochar adsorption has become an important technology to remove organic pollutants. Pyrolytic biochars (BC400, BC500, and BC600) were prepared from corn straw and then were modified by KOH to obtain KBC400, KBC500, and KBC600. Among them, KBC400 was selected for secondary pyrolysis activation at 400-600℃ to obtain AKBC400, AKBC500, and AKBC600. The structure characteristics and surface properties of AKBC were also characterized. The adsorption kinetics and thermodynamic characteristics of oxytetracycline hydrochloride (OTC) in the solution by AKBC were investigated using batch experiments. Compared to that of BC400, the specific surface area and pore structure of AKBC were significantly improved, and the aromaticity was also enhanced, resulting in the notable enhancement of the adsorption capacities for OTC. The pseudo-second-order kinetics model could better fit the adsorption process, and AKBC500 had the largest adsorption rate constant and capacity. Both the intraparticle diffusion and film diffusion were the rate-limiting steps. The Langmuir, Freundlich, and Temkin models could fit the adsorption isotherms perfectly. The adsorption of OTC on AKBC was a spontaneous, endothermic, and entropy-increasing process by both physisorption and chemisorption. The pH values in the range of 3.0-7.0 were favorable for the adsorption of OTC by AKBC. The adsorption capacity decreased with the humic acid concentration over 10 mg·L-1. The adsorption mechanism of OTC by AKBC involved pore filling, hydrogen bonding, π-π conjugation, cation-π bond, and strong electrostatic effect. AKBC still had good reusability for OTC removal after five times of regeneration. The obtained AKBC is a potential adsorbent for OTC removal from water due to the good pore structure, high adsorption capacity, and stable adsorption effect.

Hierarchical porous carbon aerogels as a versatile electrode material for high-stability supercapacitors.

Supercapacitors (SCs), as new energy storage devices with low cost and high performance, urgently require an electrode material with good pore structure and developed graphitization. Herein, we report a 3D hierarchical porous structured carbon aerogel (CA) obtained via dissolving-gelling and a subsequent carbonizing process. The gelling process was realized by using different types of anti-solvents. The carbon aerogel-acetic acid (CA-AA) has a specific surface area of 616.97 m2 g-1 and a specific capacitance of 138 F g-1 which is superior to cellulose-based active carbon. The CA was assembled into a SC, which showed excellent cycle stability. After charging and discharging 5000 times at the current density of 1 A g-1, the capacitance retention ratio of CA-AA reaches 102%. In addition, CA-AA has an energy density of 10.06 W h kg-1 when the power density is 181.06 W kg-1. It provides a choice for non-activation to effectively regulate the porous structure of biomass carbon materials.

Influence of coupled dissolution-precipitation processes on the pore structure, characteristics, and evolution of tight sandstone: A case study in the upper Paleozoic reservoir of Bohai Bay Basin, eastern China

Due to the limitations of pore throat characterization techniques, in-depth studies on the evolution and influencing variables of tight sandstone reservoirs remain lacking, despite the importance of pore structure in evaluating their storage and seepage capacities. In this study, the effect of coupled dissolution–precipitation on the heterogeneity of the pore structure of tight sandstone was investigated using advanced techniques in conjunction with traditional geochemical analyses. The primary reasons for the variability in tight sandstone pore structure were different diagenetic processes and tectonic evolution. In tight sandstones, numerous burial phases led to a significant loss of porosity. However, tight sandstones that have been successively leached by meteoric water and deep burial organic acid have improved secondary pore space due to Yanshan tectonic uplift and Himalayan tectonic burial. The redistribution or blockage of pore space can occur as a result of dissolved material migrating and re-precipitating in tight sandstones that have been deeply buried and altered by organic acidic fluids. Furthermore, nuclear magnetic resonance cryoporometry and nuclear magnetic resonance experiments were used to provide precise and accurate quantitative analysis for discussing the evolution of pore structure by complex dissolution–precipitation process within the pore scale. The formation of good pore structure was mainly dependent on the increase in pore volume generated by dissolution in the submicron and micron range (less than 10 μm). Due to interfacial energy effects, authigenic minerals precipitated preferentially in macropores, resulting in a preponderance of microporosity and small changes in porosity but at least an order of magnitude reduction in permeability. This study provides a reliable reference for genesis analysis and evaluation of tight sandstones as well as a new perspective for understanding the formation and evolution of complex pore structures.

Boron and nitrogen doping modulating the coordination environment of copper in biochar for reformative electrocatalytic CO2 reduction

In the past decades, the widespread application of heavy metal phytoremediation technology in soil has led to an increase in the yield of hyperaccumulating plants year by year. Therefore, there was a pressing demand for exploring an efficient reprocessing method to utilize the plant tissue loaded with heavy metals. Elsholtzia Harchowensis is the hyperaccumulating plant that can enrich copper, and it has a common distribution in copper areas and has been applied in the field of soil remediation of copper tails. Carbon dioxide (CO2), as a major greenhouse gas, its emission reduction and resource utilization are of great significance for China to achieve the "carbon peaking and carbon neutrality strategy". Electrochemical methods have received widespread attention due to their advantages such as mild conditions and controllable products. Copper-based materials, which can convert CO2 into utilizable fuels or chemicals, are currently hot catalysts in this field. This study prepared two types of copper containing biochar, Cu/C-BN and Cu/C, using Elsholtzia Harchowensis as raw material. The rich types of elements in plant cells make the catalyst have special spatial structure and element composition, and both catalysts exhibited good pore structures. Meanwhile, the introduction of two non-metallic elements, B and N, suppressed the hydrogen evolution reaction (HER) in the system, and the Faraday efficiency (FE) of methane (CH4) was significantly improved. In a 1.0 M KHCO3, the Cu/C-BN material electrode had an instantaneous current density of 13.8 mA/cm2 at -0.82 V vs. RHE. The electrode potential was -0.32 V vs. RHE under the condition of electrolytic 8 h, the current reached a stable value of 0.33 mA/cm2, resulting in a FE of 31.3 % for CH4 and 26.9 % for carbon monoxide (CO). On contrary, the FE of CH4 and CO was only 1.5 % and 19.8 % for Cu/C material at -0.32 V vs. RHE, respectively. The doping of both boron and nitrogen significantly improved the electrochemical activity and CH4 selectivity towards CO2RR.

Preparation and physicochemical properties of biochar from the pyrolysis of pruning waste of typical fruit tree in north China

Routine maintenance of fruit trees generates a substantial quantity of pruning waste each year. This waste is potential feedstock for producing energy, materials, and other products. The feasibility of making biochar from the waste via pyrolysis was evaluated. The effects of seven tree species, different pruning sites, and temperature on the pyrolysis process, and the physicochemical properties of the biochar were studied. Pyrolysis of different tree species at 500 °C yielded 27.5 to 33.3% biochar, with a high calorific value (approximately 30 MJ/kg), low ash content (approximately 4%), and capturing up to 60% of the carbon element present. Simultaneously, when the temperature was increased from 400 to 700 °C, the yield of biochar decreased from 35.8% to 24.3%, but the properties improved with the higher heating value rising from 29.2 to 31.3 MJ/kg and the iodine value from 234 to 252 mg/g. The biochar has a good pore structure with a specific surface area of 237 m2/g, total pore volume of 0.175 cm3/g, and average pore size of 2.96 nm. In general, biochar from the pyrolysis of fruitwood pruning waste generated here could be an ideal feedstock to produce high-value-added products, such as solid fuels, activated carbon, and electrode materials.

Construction and Evaluation of Alginate Dialdehyde Grafted RGD Derivatives/Polyvinyl Alcohol/Cellulose Nanocrystals IPN Composite Hydrogels.

To enhance the mechanical strength and cell adhesion of alginate hydrogel, making it satisfy the requirements of an ideal tissue engineering scaffold, the grafting of Arg-Gly-Asp (RGD) polypeptide sequence onto the alginate molecular chain was conducted by oxidation of sodium periodate and subsequent reduction amination of 2-methylpyridine borane complex (2-PBC) to synthesize alginate dialdehyde grafted RGD derivatives (ADA-RGD) with good cellular affinity. The interpenetrating network (IPN) composite hydrogels of alginate/polyvinyl alcohol/cellulose nanocrystals (ALG/PVA/CNCs) were fabricated through a physical mixture of ion cross-linking of sodium alginate (SA) with hydroxyapatite/D-glucono-δ-lactone (HAP/GDL), and physical cross-linking of polyvinyl alcohol (PVA) by a freezing/thawing method, using cellulose nanocrystals (CNCs) as the reinforcement agent. The effects of the addition of CNCs and different contents of PVA on the morphology, thermal stability, mechanical properties, swelling, biodegradability, and cell compatibility of the IPN composite hydrogels were investigated, and the effect of RGD grafting on the biological properties of the IPN composite hydrogels was also studied. The resultant IPN ALG/PVA/CNCs composite hydrogels exhibited good pore structure and regular 3D morphology, whose pore size and porosity could be regulated by adjusting PVA content and the addition of CNCs. By increasing the PVA content, the number of physical cross-linking points in PVA increased, resulting in greater stress support for the IPN composite hydrogels of ALG/PVA/CNCs and consequently improving their mechanical characteristics. The creation of the IPN ALG/PVA/CNCs composite hydrogels' physical cross-linking network through intramolecular or intermolecular hydrogen bonding led to improved thermal resistance and reduced swelling and biodegradation rate. Conversely, the ADA-RGD/PVA/CNCs IPN composite hydrogels exhibited a quicker degradation rate, attributed to the elimination of ADA-RGD by alkali. The results of the in vitro cytocompatibility showed that ALG/0.5PVA/0.3%CNCs and ADA-RGD/PVA/0.3%CNCs composite hydrogels showed better proliferative activity in comparison with other composite hydrogels, while ALG/PVA/0.3%CNCs and ADA-RGD/PVA/0.3%CNCs composite hydrogels displayed obvious proliferation effects, indicating that PVA, CNCs, and ADA-RGD with good biocompatibility were conducive to cell proliferation and differentiation for the IPN composite hydrogels.

Unveiling the role of reactive magnesia and red mud in CO2-cured aerated concrete

Instead of using ordinary Portland cement (OPC), this study investigated the use of hydrated magnesia carbonates, which is derived from the carbonation of reactive magnesia, as the binding material for the production of aerated concrete, where the impacts of material design (e.g., the Ca/Mg ratio) on the properties of aerated concrete were studied. The results showed that the selection of Ca/Mg and water/binder ratio in raw materials directly determined most properties of the aerated concrete, and the use of reactive magnesia enabled the samples to reveal excellent carbon sequestration and a good pore structure. Further, substituting fly ash with red mud improves early strength by forming small amounts of AFt (3CaO·Al2O3·3CaSO4·32H2O) and hydrotalcite. In view of the above, adopting CO2 curing for aerated concrete involving reactive magnesia and red mud is beneficial when producing high-quality aerated concrete (AC).

Effect of microwave drying on physical and sensory properties of instant mung bean vermicelli

Mung bean vermicelli is manufactured from mung bean starch by mixing, extruding, boiling, cooling, freezing, defrosting and sun drying. However, the end product requires a long rehydration time. Hence, this study investigated microwave drying technology to reduce the rehydration time. Instant mung bean vermicelli was dried in a continuous microwave dryer at 50 Hz, 60 Hz, and 70 Hz with different numbers of rounds. The dried mung bean vermicelli was analyzed for its physical and sensory properties. The experimental design involved 3 treatments (50 Hz, 60 Hz, 70 Hz) with 3 replications of each treatment (3x3). The results indicated that drying at 70 Hz for 16 rounds produced instant vermicelli that had a very good porous structure and good cooking quality. The vermicelli dried at 70 Hz, 60 Hz, and 50 Hz rehydrated within 2.79, 2.81 and 3.05 min, respectively. Compared to a commercial product, the color of the microwaved vermicelli was greater in lightness (L*), greenness (a*), and blueness (b*). There were no significant differences in tensile strength among the 60Hz and 70Hz treatments and the commercial product; however, the elasticity of the microwaved vermicelli samples was lower than for the commercial product. Notably, the overall acceptability scores for the microwaved dried vermicelli at 70 Hz and for the commercial product were the same (7.03 score based on a 9-point hedonic scale). In conclusion, continuous microwave drying technology at 70 Hz was recommended for instant mung bean vermicelli production due to its short drying (18.88 min) and rehydration (2.76 min) times and its good quality with a high level of acceptability