Vacuum Freeze-drying Method Research Articles

Efficient adsorption of flavonoids on amino-functionalized ZIF-8/chitosan aerogels

Covalent organic structures (MOFs), known for their exceptional properties in separation and purification, have garnered significant attention. However, applying MOF-based adsorbents in complex flavonoid separation scenarios remains challenging. In this study, we successfully synthesized adsorbent materials capable of efficiently adsorbing flavonoids using a vacuum freeze-drying method. The materials were derived from a cross-linked chitosan aerogel functionalized with amino-substituted zeolite imidazolium ester skeleton (ZIF-8). The ZIF-8-NH2, synthesized via in situ substitution of 2-aminobenzimidazole within the ZIF-8 framework, exhibits a smaller pore size than mono ligand ZIF-8. Due to its synergistic interaction with chitosan's biocompatibility and porous structure, the aerogel material (ZIF-8-NH2/CS) exhibited outstanding adsorption capacities (183.37 mg/g, 226.34 mg/g, and 187.16 mg/g) in standard solutions (T = 318 K, rpm = 200) of luteolin, quercetin, and rutin, along with high adsorption rates (71.3 ± 2.3 %, 72.4 ± 1.4 %, and 70.7 ± 3.5 %). And showed rapid adsorption in the first 60 min. After 5 cycles, the adsorption capacity of ZIF-8-NH2/CS aerogel remained at 80.5 % of the adsorption capacity of the initial cycle, and therefore, ZIF-8-NH2/CS aerogel has a good potential for reusability. Additionally, the adsorption process adhered to pseudo-first-order and pseudo-second-order kinetic models, alongside Langmuir and Freundlich isothermal adsorption models. This study introduces novel ideas and methods for the extraction and separation of flavonoids. Furthermore, the developed ZIF-8-NH2/CS aerogels with amino functionality hold promise for diverse applications in separating and purifying bioactive substances.

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.

Insight into the changes in active metabolite profiles of noni (Morinda citrifolia L.) fruit subjected to different drying treatments

Noni fruit is renowned for its abundance of bioactive compounds. Drying is an important method for processing functional products derived from noni. However, limited information exists on how drying methods affect the active metabolite profiles of noni fruit. This study investigated the impact of four common drying methods, including hot-air drying (HAD), vacuum freeze drying (VFD), microwave drying (MWD), and far infrared drying (FID), on the physicochemical indexes, bioactive components, and functional properties of dried noni fruit slices using targeted and untargeted metabonomics analysis. The results showed significant variations in appearance, water migration, and microstructure of dried noni fruit slices subjected to the four drying methods. VFD treatment yielded better dried noni fruit products when compared to other drying methods. The superiority of VFD treatment was due to its uniform stratification, reduced collapse, better retention of bioactive components and antioxidants, and higher enzyme inhibitory rates. These findings suggest that VFD method is ideal for obtaining premium bioactive profiles and maintaining the biological activity of noni fruit.

Flavor Variations in Precious Tricholoma matsutake under Different Drying Processes as Detected with HS-SPME-GC-MS.

By employing headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), this study displayed the compositional changes in volatile organic compounds (VOCs) in Tricholoma matsutake samples subjected to hot-air drying (HAD) and vacuum freeze-drying (VFD) processes from their fresh samples. A total of 99 VOCs were detected, including 2 acids, 10 aldehydes, 10 alcohols, 13 esters, 12 ketones, 24 alkanes, 14 olefins, 7 aromatic hydrocarbons, and 7 heterocyclic compounds. Notably, the drying process led to a decrease in most alcohols and aldehydes, but an increase in esters, ketones, acids, alkanes, olefins, aromatic, and heterocyclic compounds. Venn diagram (Venn), principal component analysis (PCA), and partial least squares-discriminant analysis (PLS-DA) analyses enabled an easy and rapid distinction between the VOC profiles of T. matsutake subjected to different drying methods. Among the identified VOCs, 30 were designated as marker VOCs indicative of the employed drying process. And the VFD method was more capable of preserving the VOCs of fresh T. matsutake samples than the HAD method. Benzaldehyde, 1-Octen-3-ol, 3-Octanol, and (E)-2-Octen-1-ol were identified as markers for FRESH T. matsutake. Conversely, (E)-3-Hexene, lavender lactone, and α-Pinene were associated with VFD T. matsutake. For HAD T. matsutake, olefins, pyrazine, and esters, particularly ocimene, 2,5-Dimethyl-pyrazine, and methyl cinnamate, significantly contributed to its particularities. The results from this present study can provide a practical guidance for the quality and flavor control of volatile organic compounds in preciously fungal fruiting bodies by using drying processes.

Application of molybdenum sulfide-graphene aerogel for solar energy-driven interfacial evaporation

Water is one of the most essential human rights, and every human being has the right to drink pure water. Approximately 2.1 billion people worldwide do not have access to safe drinking water, and with a growing population, increasing global industrialization has intensified water stress in many parts of the world. Solar-driven interfacial evaporation, as a sustainable and environmentally friendly technology, transforms external solar energy into thermal energy through a photothermal evaporator to produce fresh water. In this paper, we prepared MoS2-rGO aerogels (MGA) from molybdenum sulfide (MoS2) and reduced graphene oxide (rGO) by one-step hydrothermal and vacuum freeze-drying methods. The prepared aerogels have vertical loose water transport channels and good mechanical properties, and the light absorption of MoS2-rGO aerogels in the solar spectrum (280–2500 nm) reached 86.3 %. The water evaporation rate under one solar radiation intensity condition reached 1.72 kg m−2 h−1 with a photothermal conversion efficiency of 86.5 %. What’s more, the MGA has good salt-resistant properties and cycling stability and always maintains a stable evaporation rate and evaporation efficiency in 15 evaporation cycle tests. In addition, the simplicity and low cost of our aerogel preparation process show a potential way to achieve water purification and desalination in daily life.

A colorimetric and fluorescent probe of lignocellulose nanofiber composite modified with Rhodamine 6G derivative for reversible, selective and sensitive detection of metal ions in wastewater

Heavy metal ions have extremely high toxicity. As the top of food chain, human beings certainly will accumulate them by ingesting food and participating other activities, which eventually result in the damage to our health. Therefore, it is very meaningful and necessary to design a simple, portable, stable and efficient material for heavy metal ions detection. Based on the spirolactam Rhodamine 6G (SRh6G) fluorescent probe, we prepared two types of nanocomposite materials (membrane and aerogel) by vacuum filtration and freeze-drying methods with lignocellulose nanofiber (CNF) as a carrier, polyvinyl alcohol (PVA) and glutaraldehyde (GA) as the cross-linkers. Then the microstructure, chemical composition, wetting property, fluorescence intensity and selectivity of as-prepared SRh6G/PVA/CNF would be characterized and analyzed. Results showed that SRh6G/PVA/CNF nanocomposites would turn red in color under strong acidic environment and produced orange fluorescence under ultraviolet light. Besides, they were also to detect Al3+, Cu2+, Hg2+, Fe3+ and Ag+ through color and fluorescence variations. We had further tested its sensitivity, selectivity, adsorption, fluorescence limits of detection (LOD) to Fe3+ and Cu2+. The test towards real water samples (hospital wastewater, Songhua River and tap water) proved that SRh6G/PVA/CNF nanocomposites could detect the polluted water with low concentrations of Fe3+ and Cu2+. In addition, SRh6G/PVA/CNF nanocomposites have excellent mechanical property, repeatability, superhydrophilicity and underwater superoleophobicity, which may offer a theoretical reference for the assembly strategy and detection application of cellulose-based fluorescent probe.

Preparing High-Quality Monolithic Carbon Nanotubes Reinforced Silica Aerogel Composites Based on a Vacuum Freeze-Drying Method

Preparing High-Quality Monolithic Carbon Nanotubes Reinforced Silica Aerogel Composites Based on a Vacuum Freeze-Drying Method

Extraction of nano-crystalline cellulose for development of aerogel: Structural, morphological and antibacterial analysis

In the present decades, nanocellulose has been very popular in the field of nanotechnology and is receiving much attention from researchers because of its advantageous physicochemical properties, high aspect ratio, and high specific strength and modulus. The available non-eco-friendly conventional methods for the extraction of nano-crystalline cellulose (NCC) use highly concentrated chemicals and are time-consuming as well. The present adopted cost-effective method for the extraction of nano-crystalline cellulose involves minimum usage of chemicals and is environmentally friendly and relatively fast compared to other conventional methods. The nano-crystalline cellulose from sisal (NCC–S) fibers were extracted by steam explosion-assisted mild concentrated chemical treatments followed by mechanical grinding. The Dynamic light scattering (DLS) and Transmission electron microscopy (TEM) characterization confirmed the size of extracted NCC-S. A high aspect ratio was observed as 19.23, which signifies it could be a promising reinforcing material in developing nanocomposites for advanced applications. An increase in crystallinity and the removal of amorphous materials for NCC-S were confirmed by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analysis, respectively. Antibacterial study shows that NCC-S did not show any antibacterial properties against E. coli and S. aureus. The calculated yield of extracted nanocellulose was about 50 %. The aerogel with a porosity of 95.1 % and a density of 0.075 g/cm3 was prepared by vacuum freeze-drying method using extracted nanocellulose and chitosan. The cross-linking network structure and thermal stability of the aerogel were also confirmed by FTIR and TGA analysis respectively.

Evaluation of the Polyethylene Glycol Impregnation and Vacuum Freeze-Drying Method for Waterlogged Archaeological Wood: Conservation of the Yenikapı 1 Shipwreck

ABSTRACT The YK 1 shipwreck, found at Yenikapı, Istanbul, is one of 37 shipwrecks dating to the medieval era. This paper describes the studies and the processes which were conducted to conserve the YK 1. Firstly, the level of physical and chemical degradation of the wood from the YK 1 was examined, which revealed that the wood was highly degraded. Therefore, PEG 2000 was chosen for the impregnation process before vacuum freeze-drying. In addition, the ASE values confirmed that the PEG 2000 impregnation and vacuum freeze-drying method together were successful in conserving the YK 1, with values higher than PEG 2000 impregnation and vacuum freeze-drying methods alone. The concentration of the PEG solution in the tank was monitored throughout the impregnation process. Following this, samples taken from the wood cores were analysed using FTIR to evaluate the effectiveness of the impregnation process. Finally, SEM was used to examine the effectiveness of the PEG 2000 impregnation and vacuum freeze-drying method. The SEM images showed that the PEG 2000 was uniformly distributed, and the wood had no deformation after freeze-drying.

Konjac Glucomannan Aerogels Modified by Hydrophilic Isocyanate and Expandable Graphite with Excellent Hydrolysis Resistance, Mechanical Strength, and Flame Retardancy.

At present, biomass foamlike materials are a hot research topic, but they need to be improved urgently due to their defects such as large size shrinkage rate, poor mechanical strength, and easy hydrolysis. In this study, the novel konjac glucomannan (KGM) composite aerogels modified with hydrophilic isocyanate and expandable graphite were prepared by a facile vacuum freeze-drying method. Compared with the unmodified KGM aerogel, the volume shrinkage of the KGM composite aerogel (KPU-EG) decreased from 36.36 ± 2.47% to 8.64 ± 1.46%. Additionally, the compressive strength increased by 450%, and the secondary repeated compressive strength increased by 1476%. After soaking in water for 28 days, mass retention after hydrolysis of the KPU-EG aerogel increased from 51.26 ± 2.33% to more than 85%. The UL-94 vertical combustion test showed that the KPU-EG aerogel can achieve a V-0 rating, and the limiting oxygen index (LOI) value of the modified aerogel can reach up to 67.3 ± 1.5%. To sum up, the cross-linking modification of hydrophilic isocyanate can significantly improve the mechanical properties, flame retardancy, and hydrolysis resistance of KGM aerogels. We believe that this work can provide excellent hydrolytic resistance and mechanical properties and has broad application prospects in practical packaging, heat insulation, sewage treatment, and other aspects.

Study on the action mechanism of Buyang Huanwu Decoction against ischemic stroke based on S1P/S1PR1/PI3K/Akt signaling pathway

Ethnopharmacological relevanceIschemic stroke is a common and frequent clinical disease. Recent studies have demonstrated that sphingolipid plays an important role in the pathological process of ischemic stroke. PI3K-Akt is a classic protective signaling pathway of cerebral ischemic injury. After acting on the S1P receptor, S1P can activate the downstream PI3K/Akt signaling pathway and play an anti-cerebral ischemia role. Buyang Huanwu Decoction (BHD) is a traditional Chinese medicine formula used to treat ischemic stroke. However, the mechanisms of BHD on ischemic stroke remain unclear based on S1P/S1PR1/PI3K/Akt signaling pathway. Aim of the studyThe present study is intended to investigate the action mechanism of BHD on ischemic stroke based on the S1P/S1PR1/PI3K/Akt signaling pathway from multiple perspectives. Materials and methodsThe BHD lyophilized product was prepared by vacuum freeze-drying method, of which the chemical composition was determined by UPLC-Q-TOF/MS. The mouse permanent middle cerebral artery occlusion (pMCAO) model was established by the suture-occluded method. Male KM mice were randomly divided into seven groups: sham group, model group, FTY720 (positive control) group, BHD group, BHD + W146 (selective S1PR1 inhibitor) group, SEW2871 (selective S1PR1 agonist) group, and Calycosin group. Each group was administered continuously for 14 days and evaluated with modified neurological severity score (mNSS) and cerebral infarct volume on the 1st, 4th, 7th, and 14th days. The SphK1, SphK2, S1PR1, PI3K, Akt, and p-Akt protein in the prefrontal lobe, hippocampus, and striatum was quantified by Western blot and immunohistochemical (IHC) experiment respectively. The qRT-PCR method was employed to evaluate SphK1, SphK2, and S1PR1 mRNA expression in the above tissue. ResultsBHD and Calycosin both effectively improved mNSS scores with smaller infarct volumes. The SphK1 level in the prefrontal lobe, hippocampus, and striatum of mice in the BHD group was significantly lower, and SphK2, PI3K, and p-Akt in the hippocampus and striatum were significantly higher than those in the model group.BHD significantly decreased SphK1 mRNA expression in the prefrontal lobe, hippocampus, and striatum, and significantly up-regulated SphK2 mRNA and S1PR1 mRNA expression. Additionally, SphK1 protein expression levels of the prefrontal lobe, hippocampus, and striatum in the BHD group was significantly lower than model group, and SphK2, S1PR1, PI3K, Akt, and p-Akt protein expressions levels were increased obviously.Furthermore, SEW2871 can increase S1PR1 and Akt expression, and up-regulate SphK2 and S1PR1 mRNA expression. The effect of BHD on the expression of S1P/S1PR1/PI3K/Akt signaling pathway-related proteins and mRNA were weakened by BHD + W146. ConclusionBHD and Calycosin significantly improved the symptoms of neurological deficits in pMCAO mice, reduced the cerebral infarction volume, up-regulated SphK2 and S1PR1 mRNA levels, enhanced SphK2, S1PR1, PI3K, Akt, p-Akt protein expression of the prefrontal lobe, hippocampus and striatum, and down-regulated SphK1 mRNA and protein expression, which may be helpful to clarify the mechanism of BHD through S1P/S1PR1/PI3K/Akt signaling pathway to protect against cerebral ischemic injury.

Form-stable phase change materials based on graphene-doped PVA aerogel achieving effective solar energy photothermal conversion and storage

Polyvinyl alcohol (PVA) aerogel is usually used to restrict the flow of liquid polyethylene glycol (PEG) for the preparation of composite phase change materials (PCM). Currently, the vacuum freeze-drying method is demonstrated to be the most valid way to prepare PVA aerogel. However, achieving a high thermal conductivity and optical thermal conversion efficiency in composite PCM remains challenging, due to the lack of effective thermal conductivity fillers and optical thermal conversion media within the reported PVA aerogel. Herein, we report a simple method to prepare PVA-reduced graphene oxide (rGO) aerogel by reductant reduction and vacuum freeze-drying methods. PVA-rGO aerogel is well suitable to accommodate PEG, and the consequent composite PCM (PEG/PVA-rGO) demonstrates an outstanding PEG loading rate of up to 96.9 wt%. In addition, due to the efficient light absorption and highly thermal conductivity of rGO, the photothermal conversion efficiency of PEG/PVA-rGO was increased to 88.2%, while also increasing its thermal conductivity to 0.348 W/(m·K). The melting enthalpy of PEG/PVA-rGO is measured to be as large as 155.5 J/g. Furthermore, the use of PEG/PVA-rGO for solar-thermal energy storage application is demonstrated. This work provides valuable guidance for preparing high-performance form-stable composite PCM and raises their potential for practical use in solar energy storage and energy-efficient buildings.

Synthesis and ciprofloxacin adsorption of Gum Ghatti /Konjac Glucomannan/Zif-8 composite aerogel

The Gum Ghatti (GG)/Konjac Glucomannan (KGM)/zeolitic imidazolate framework-8 (ZIF-8) composite aerogels (GKZ) were synthesized by the sol-gel method and the vacuum freeze-drying method for effective removal of ciprofloxacin (CIP) from contaminated water. The results showed that the addition of different concentrations (0, 0.4, 0.6, 0.8 wt%) of GG could promote homogeneity but weakened the molecular interaction of the aerogel system without water. Remarkably, the ZIF-8 maintained the crystal structure, as well as its dispersion on the surface of aerogel, was significantly improved. Additionally, it was also found that the incorporation of moderate GG was favored regarding CIP adsorption, and GKZ with 0.6 % GG (GKZ0.6) exhibited the highest adsorption capability for CIP around 1035.4 mg/g. Besides, the effects of various ions, ionic strength, and pH on CIP adsorption were also investigated, which provided the reference for guiding the utilization of GKZ0.6. Furthermore, at fewer cycles, the adsorption efficiency of GKZ0.6 on CIP showed less loss. These features revealed that the GKZ composite aerogels might be a promising adsorbent for CIP removal from water.

Characterizations and great application potential for air filtration of konjac glucomannan/curdlan aerogels

The pore size distribution and pore number had a great impact on the air filtration performance of polysaccharide-based aerogels. In this study, konjac glucomannan (KGM)/curdlan (KC) aerogels were prepared by the vacuum freeze-drying method, and the microstructure, molecular interaction, mechanical property, thermal stability, and air filtration performance were investigated. Results indicated that KGM and curdlan showed good compatibility based on hydrogen bonds and formed complete aerogel with three-dimensional network structure. KC1.2 displayed the highest compressive stress and thermal stability. With the addition of curdlan, the pore size decreased and the pore number increased, which resulted in the improvement of filtration efficiency. However, the high number (up to 1200) of pores in KC1.2 caused a decrease of filtration efficiency, and KC1.2 showed high air resistance (up to 1000 Pa). For PM1.0 and PM2.5, all KC aerogels had high filtration efficiency of more than 80 %. Considering the filtration efficiency and air resistance, KC0.9 was regarded as the optimum material for air filtration. All KC aerogels maintained stable filtration efficiency and pore structure after fifteen filtration cycles, demonstrating a long service life. These results indicated that KC aerogel had great potential for application in air filtration.

Methylene Blue Removed from Aqueous Solution by Encapsulation of Bentonite Aerogel Beads with Cobalt Alginate.

It can be difficult to remove dark methylene blue (MB) from water effectively. The use of sodium alginate and bentonite (Ben) as the matrix produced a displacement reaction that occurred in cobalt chloride, which allowed Ben to be successfully encapsulated in cobalt alginate (CA). Finally, a vacuum freeze-drying method was used to prepare a low-cost composite of CA/Ben aerogel for adsorbing MB in aqueous solutions. In addition to scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy, the composites were also characterized and analyzed. Different adsorption experiments were conducted in order to determine the effects of dosage, pH, adsorption time, and temperature on the adsorption performance of the adsorbent. According to the results of the experiment, the adsorption capacity of CA/Ben aerogel was 258.92 mg·g-1, and the pseudo-first-order kinetic model and Freundlich isotherm model can fully explain the adsorption process of MB on this aerogel. The composite material reported in this paper is easily recycled, and the removal rate reaches 65% after four times of recycling. Moreover, compared with other adsorbents, the composite material of the invention is highly environmentally friendly and has a simple preparation process. A large-scale application of this technology is the removal of dyes from water on a large scale.

Adsorption Capacity of Tetracycline in Solution by Cu-BTC@Carboxyl-Functionalized Carbon Nanotubes@Copper Alginate Composite Aerogel Beads

In order to remove tetracycline (TC) from sewage more effectively, the adsorption performance of TC on alginate composite aerogel beads containing carbon nanomaterials was studied systematically. Carboxylated functionalized carbon nanotubes (F-CNTs)@Cu-based metal-organic framework (Cu-BTC) carbon nanomaterial composites (F-C) were prepared by a hydrothermal method, and the F-C powders were coated and fixed by macromolecular polymer copper alginate (CA). Then, F-CNTs@Cu-BTC@CA composite aerogel beads (F-C-CA) were prepared by a vacuum freeze-drying method. The new composite was characterized by BET, SEM, FTIR, and TGA, and its physical and chemical properties were analyzed. The results of batch adsorption experiments showed that F-C-CA aerogel beads had excellent adsorption capacity for TC. At 303 K, 10 mg F-C-CA aerogel beads adsorbed 20 mL 100 mg·L−1 TC solution; the removal rate reached 94% after 48 h. After kinetic analysis, the adsorption process of F-C-CA on TC was found to be more coherent with the pseudo-second-order kinetic model (chemisorption process). The isotherm fitting analysis indicated that the adsorption behavior was more suitable to the Langmuir model (monolayer adsorption), and the fitted maximum adsorption was 297 mg·g−1.

A silk fibroin/chitosan/nanohydroxyapatite biomimetic bone scaffold combined with autologous concentrated growth factor promotes the proliferation and osteogenic differentiation of BMSCs and repair of critical bone defects.

PurposeWith the goal of increasing the translational efficiency of bone tissue engineering for practical clinical applications, biomimetic composite scaffolds combined with autologous endogenous growth factors for repairing bone defects have become a current research hotspot. In this study, we prepared a silk fibroin/chitosan/nanohydroxyapatite (SF/CS/nHA) composite biomimetic scaffold and then combined it with autologous concentrated growth factor (CGF) to explore the effect of this combination on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the efficiency of repairing critical radial defects.MethodsThree kinds of SF/CS/nHA composite biomimetic scaffolds with mass fractions of 3%, 4%, and 5% were prepared by vacuum freeze-drying and chemical cross-linking methods, and the characteristics of the scaffolds were evaluated. In vitro, BMSCs were seeded on SF/CS/nHA scaffolds, and then CGF was added. The morphology and proliferation of BMSCs were evaluated by live-dead staining, phalloidin staining, and CCK-8 assays. ALP staining, alizarin red staining, cellular immunofluorescence, RT–PCR, and Western blotting were used to detect the osteogenic differentiation of BMSCs. In vivo, a rabbit radius critical bone defect model was constructed, and the SF/CS/nHA-BMSC scaffold cell complex combined with CGF was implanted. The effect on bone defect repair was evaluated by 3D CT scanning, HE staining, Masson staining, and immunohistochemistry.ResultsThe characteristics of 4% SF/CS/nHA were the most suitable for repairing bone defects. In vitro, the SF/CS/nHA combined CGF group showed better adhesion, cell morphology, proliferation, and osteogenic differentiation of BMSCs than the other groups (P < 0.05 for all). In vivo imaging examination and histological analysis demonstrated that the SF/CS/nHA scaffold combined with CGF had better efficiency in bone defect repair than the other scaffolds (P < 0.05 for all).ConclusionsA SF/CS/nHA composite biomimetic bone scaffold combined with autologous CGF promoted the proliferation and osteogenic differentiation of BMSCs in vitro and improved the repair efficiency of critical bone defects in vivo. This combination may have the potential for clinical translation due to its excellent biocompatibility.

Biological Application of Novel Biodegradable Cellulose Composite as a Hemostatic Material.

Degradable hemostatic materials have unique advantages in reducing the amount of bleeding, shortening the surgical operation time, and improving patient prognosis. However, none of the current hemostatic materials are ideal and have disadvantages. Therefore, a novel biodegradable cellulose-based composite hemostatic material was prepared by crosslinking sodium carboxymethyl cellulose (CCNa) and hydroxyethyl cellulose (HEC), following an improved vacuum freeze-drying method. The resulting cellulose composite material was neutral in pH and spongy with a density of 0.042 g/cm3, a porosity of 77.68%, and an average pore size of 13.45 μm. The composite's compressive and tensile strengths were 0.1 MPa and 15.2 MPa, respectively. Under in vitro conditions, the composites were degraded gradually through petite molecule stripping and dissolution, reaching 96.8% after 14 days and 100% degradation rate at 21 days. When implanted into rats, the degradation rate of the composite was slightly faster, reaching 99.7% in 14 days and 100% in 21 days. Histology showed a stable inflammatory response and no evidence of cell degeneration, necrosis, or abnormal hyperplasia in the tissues around the embedded material, indicating good biocompatibility. In the hemorrhagic liver model, the time to hemostasis and the total blood loss in the cellulose composite group was significantly lower than in the medical gauze group and the blank control group (P < 0.05). These data indicate that the novel cellulose composite is a promising implantable hemostatic material in clinical settings.

Fabrication of nickel cobalt bimetallic sulfide doped graphite carbon nanohybrids as electrode materials for supercapacitors

A series of nickel cobalt bimetallic sulfide doped graphite carbon (NCBS/C) nanohybrids were fabricated by cross linking reaction, vacuum freeze-drying, heat treatment and hydrothermal method using sodium alginate (SA) as carbon source, nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O) as transition metal ions source, thiourea as sulfur source. The electrochemical properties of the NCBS/C nanohybrids as electrode materials could be tuned by adjusting the composition. The results show that the NCBS/C nanohybrid fabricated at the molar ratio of Ni(NO3)2·6H2O to Co(NO3)2·6H2O of 1:1, and the thiourea amount of 0.1 g had the optimal electrochemical properties, the specific capacity was 742.9C g−1 at 1 A g−1, when the current density increased from 0.5 A g−1 to 5 A g−1, the specific capacity could remain 98.2%. The asymmetric supercapacitor assembled by the NCBS/C nanohybrid as the positive electrode, activated carbon as the negative electrode delivered energy density of 53.00 Wh kg−1 at power density of 850 W kg−1, and still maintained 43.57 Wh kg−1 at 4.24 kW kg−1. Moreover, the device had 83.78% capacitance retention after 5000 charge-discharge cycles at 5 A g−1. The nanohybrids with high electrochemical properties could be attributed that the transition metal ions as cross-linking agents were well dispersed in the SA hydrogels as carbon source, resulting in that the in-situ formed nickel cobalt bimetallic sulfide nanoparticles were uniformly doped in graphite carbon materials. The strategy could be applied to fabricate other transition metals compounds doped carbon materials for the development of other high-performance electrode materials.

Vacuum-Freeze Drying Assist for the Fabrication of a Nickel-Aluminium Catalyst and Its Effects on the Structure-Reactivity in the Catalytic Dry Reforming of Methane

Abstract In this study, a co-precipitation coupled with vacuum-freeze drying (VFD) method was adopted to fabricate a highly mesoporous nickel-aluminium catalyst (VFD-cat). VFD-cat with uniform smaller pore size and a larger BET surface area were obtained than the catalysts prepared following the conventional thermal evaporation drying method (TED-cat). In addition, the VFD method helps to improve the dispersion of precursors, which then enhances the strong metal-support interactions (MSI) of VFD-cat via forming substoichiometric NiAl2O4 spinel. Characterization showed that the average nickel particle size on the VFD-cat was smaller than that of the TED-cat, attributed to the confinement effects of MSI. At 800 °C, the VFD-cat exhibited higher stability during the long-term dry reforming of methane (DRM) test. It was found that the coke formation on spent VFD-cat, especially for the ordered carbon species, was significantly eliminated as compared with TED-cat after the stability test. This strategy offers a facile way to develop DRM catalysts with highly mesoporous and MSI, enhancing the catalytic stability and coke resistance of the nickel-aluminium catalyst.