Chitosan (CS) is a natural biopolymer that shows promise as a biomaterial for bone-tissue regeneration. However, because of their limited ability to induce cell differentiation and high degradation rate, among other drawbacks associated with its use, the creation of CS-based biomaterials remains a problem in bone tissue engineering research. Here we aimed to reduce these disadvantages while retaining the benefits of potential CS biomaterial by combining it with silica to provide sufficient additional structural support for bone regeneration. In this work, CS-silica xerogel and aerogel hybrids with 8 wt.% CS content, designated SCS8X and SCS8A, respectively, were prepared by sol-gel method, either by direct solvent evaporation at the atmospheric pressure or by supercritical drying in CO2, respectively. As reported in previous studies, it was confirmed that both types of mesoporous materials exhibited large surface areas (821 m2g-1-858 m2g-1) and outstanding bioactivity, as well as osteoconductive properties. In addition to silica and chitosan, the inclusion of 10 wt.% of tricalcium phosphate (TCP), designated SCS8T10X, was also considered, which stimulates a fast bioactive response of the xerogel surface. The results here obtained also demonstrate that xerogels induced earlier cell differentiation than the aerogels with identical composition. In conclusion, our study shows that the sol-gel synthesis of CS-silica xerogels and aerogels enhances not only their bioactive response, but also osteoconduction and cell differentiation properties. Therefore, these new biomaterials should provide adequate secretion of the osteoid for a fast bone regeneration.

Energy consumption, specifically in the building sector, is expected to rise. One potential way to reduce energy consumption, or to slow this increase, is to reduce the heat loss in residential homes. Silica aerogels have grown in popularity as an insulating material due to their extremely low thermal conductivity. However, the benefits of using silica aerogels as an insulator in residential buildings have not been thoroughly studied. To understand the benefits of using silica aerogels as a thermal insulator in residential homes, experimentally validated simulations were performed. The simulations were performed on a model of a full-scale residential house using the multiphysics software ANSYS FLUENT 2019 R2. The simulations helped predict the actual saving benefits of using aerogels as an insulator. Aerogels have the potential to be used as an insulator in both the walls and windows due to its semitransparency. The results showed that the average kWh savings using one half-inch layer of wall aerogel insulation coupled with window aerogel insulation was 20.9% for the single-family house compared to traditional insulation. On average, the energy lost through the windows was 39.1% lower when using aerogel insulation compared to standard insulating materials. The energy lost through the house walls was 13.3% lower on average when using a thin layer of aerogel insulation. While a thin layer of aerogel insulation provided a benefit when used in the house walls, the potential for savings per quantity used was greater in the windows.

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1-15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210-596 m2·g-1, an apparent density of 0.403-0.740 cm3·g-1 and a porosity of 60-78%. The actual cobalt content in the aerogels was 0.01-1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.

Thermal insulation has great potential to reduce energy consumption in buildings. This study aims to provide a general perspective by addressing the thermal insulation materials used throughout the history of the construction industry and to understand the current situation with developing technology. The literature review was used as a method in the study. The insulation values of current thermal insulation products were investigated and compared. An energy loss and gain analysis were carried out on the Revit-2019 model to understand the difference between the widely used rock wool and a nanotechnology product, aerogel-added thermal insulation material. In addition, the effect of the use of these products on the building cost is emphasized. The results of the study show that thermal insulation materials produced with nanotechnology examined have lower thermal conductivity coefficients compared to other thermal insulation materials. According to the analysis carried out on the Revit-2019 (Autodesk Revit Architecture/3D) model, the thermal insulation material with aerogel provides 8% savings in cooling loads compared to the use of rock wool. As a result of the analysis made on the Revit-2009 model, it was concluded that 8% savings were achieved in cooling loads in the use of aerogel-added materials compared to the use of rock wool, but the initial investment cost was high. Developing competitive and sustainable materials is of the utmost importance. The literature review suggests that new composite insulators can be produced by combining suitable materials.

For aerogels in metal thermal protection system (MTPS), radiative heat transfer will participate in the thermal transport process. Therefore, the influence of the emissivity of the coupling interface between metal and aerogels on thermal insulation performance is considered an important research focus. In this paper, CFD numerical simulation is performed to study the influence of emissivity on the performance with different extinction coefficients at different boundary temperatures. The finite volume method and the discrete ordinate method are used to solve the govern equations. The results show that when the boundary temperatures are 600 K and 2100 K, the extinction coefficient is 50 m-1, and the reduction percentage of the effective thermal conductivity with an emissivity of 0.2 can be up to 47.5% and 69.8%, compared to the system with an emissivity of 1. Thus, the reduction in emissivity has a good effect on the thermal insulation performance of the MTPS at a higher boundary temperature for materials with small extinction coefficients.

Salecan, a water-soluble microbial polysaccharide with attractive biocompatible characteristics, is very suitable for aerogel fabrication. However, the practical application of salecan-based aerogels for cell culture was limited by complicated preparation method, lack of cell anchorage signals, and the ability to modulate this properly. Here, a smart aerogel was designed by ultrasonic-assisted self-assembly of salecan and cationic starch (CAS) without any organic and toxic crosslinkers. The ultrasound waves generated a marked impact on self-assemble process by means of ultrasonic cavitation. Aerogel network was produced by strong electrostatic attractions between the polysaccharides. Especially, salecan/CAS ratio can be precisely modulated to tailor the hydrophilicity, mechanical stiffness, and morphologic property. The specific surface area of the aerogels gradually increased with the increase in salecan/CAS ratio. These aerogels were non-cytotoxic, and the incorporation of salecan into them promoted cell-matrix interactions by directionally supporting cell adhesion and proliferation. Most strikingly, in vivo experiment revealed that the histological features in the main organs of the mice were similar to those observed in the PBS-treated control group, and no sign of the histopathological abnormality or tissue destruction was observed, indicating the excellent histocompatibility of the aerogels. This study offered a new and powerful avenue to fabricate functional biomaterial.

Bimetallic alginate aerogel beads were prepared by ionotropic gelation method with Ca2+-Ba2+ bimetallic solution and ibuprofen was loaded as a model drug. The swelling and drug releasing behaviors of the beads, especially the influence of barium, were investigated in artificial gastric and intestinal fluids. The results showed that these beads presented higher encapsulation efficiency due to the special structure of aerogel, and barium was beneficial for the more stable structure and drug releasing behavior. The lower swelling capacity of bimetallic beads was observed than monometallic beads. A rapid high-level releasing of ibuprofen was achieved in artificial intestinal fluid, which was up to 96.9% within 1 h, while ibuprofen releasing was avoided in artificial gastric fluid effectively. The drug releasing mechanism of these beads was explored in detail. In the bimetallic crosslinking system, Ba2+ presented a special effect on alginate beads with more sensitive pH response performance. Thus, these beads had more widely potential as a site-specific delivery system, especially for intestinal therapy.

The feasibility of producing food-grade hydrophobic bio-aerogels by supercritical-carbon dioxide (SC-CO2) extraction of oil from oleogels was investigated for the first time. Medium chain triglycerides (MCT) oil was gelled using ethylcellulose (EC) at increasing concentration (10, 15, 20% w/w) and grade (EC20, 45, 100), eventually in combination with fillers. Different SC-CO2 oil extraction procedures were tested. The acquired results show that both oleogel formulation and extraction conditions can steer the EC scaffold structure. The increase in EC concentration and grade resulted in oleogels more structurally stable to SC-CO2 extraction. The application of a pulsed extraction procedure allowed obtaining a low-density (0.39 ​g/cm3) EC scaffold presenting 60% oil. Addition of freeze dried lettuce powder improved macrostructure homogeneity. The obtained results lay the foundations for developing food-grade hydrophobic bio-aerogels, which are expected to present unique oil absorption and bioactive delivery features.

Herein, multiscale nanocelluloses (NCs) were prepared and blended with fumed silica and organosilane to fabricate freeze-dried aerogels in various combinations. The cooperation of multiscale raw materials optimized the porous structures of aerogels, thus improving the thermal insulation properties. The use of NCs with different characteristics endowed the resultant aerogels with distinct mechanical performance. The addition of high-aspect-ratio NCs in the composite aerogels was essential for improving the bendability. Furthermore, lower-aspect-ratio NCs helped to resist the compression deformation of the cross-linked aerogels. The functional groups on NCs made a difference in the thermal stability of the as-prepared aerogels. However, after treating at 150-350 ℃, the aerogels could maintain structural integrity and high elastic recovery rate, possessing ultralow density (7.2 kg/m3) and thermal conductivity (25.4 mW m-1 K-1). The outstanding thermal properties and controllable mechanical performance make these aerogels potential candidates in different fields such as textile and building industries.

In this paper, a silica aerogel support was prepared by two-step sol-gel method, and the active component K2CO3 was supported on the support by wet loading to obtain a modified potassium-based CO2 adsorbent. As the influences of reaction conditions on the CO2 capture characteristics of modified potassium-based adsorbents, the reaction temperature (50 °C, 60 °C, 70 °C, 80 °C), water vapor concentration (10%, 15%, 20%), CO2 concentration (5%, 10%, 12.5%, 15%), and total gas flow rate (400 mL/min, 500 mL/min, 600 mL/min) were studied in a self-designed fixed-bed reactor. At the same time, the low-temperature nitrogen adsorption experiment, scanning electron microscope, and X-ray diffractometer were used to study the microscopic characteristics of modified potassium-based adsorbents before and after the reaction. The results show that the silica aerogel prepared by the two-step sol-gel method has an excellent microstructure, and its specific surface area and specific pore volume are as high as 838.9 m2/g and 0.85 cm3/g, respectively. The microstructure of K2CO3 loaded on the support is improved, which promotes the CO2 adsorption performance of potassium-based adsorbents. The adsorption of CO2 by potassium-based adsorbents can be better described by the Avrami fractional kinetic model and the modified Avrami fractional kinetic model, and it is a complex multi-path adsorption process, which is related to the adsorption site and activity. The optimal adsorption temperature, water vapor concentration, CO2 concentration, and total gas volume were 60 °C, 15%, 12.5%, and 500 mL/min, respectively.