查找使用阿拉丁产品的科研文献

Lightweight, Flexible and Hydrophobic Cotton Fiber/Silica Aerogel Composite by Freeze-Drying for Organic Solvent/Water Separation and Thermal Insulation

Huo Jian-Chun,Yang Hai-Xia,Ma Yuan,Bai Jie

Natural cotton fiber used for reinforcement is low-cost, environmentally friendly, good flexibility and easy to obtain. In this study, a new cotton fiber/silica aerogel composite was developed by sol–gel method via freezedrying. The obtained composite has excellent flexibility and can be restored to its original state after bending for 180° without obvious cracks. After 20 cycles continuous compression, the total unrecoverable strain loss is only 20% under strain of 60%. The composite also shows very prominent hydrophobicity, and the contact angle with water reaches 145 degrees. It has strong adsorption capacity for organic reagents and oil, with adsorption ratios of 500% and 600%, respectively. In addition, the composite has a low thermal conductivity of 0.038 W/(m·K) at room temperature. The obtained composite exhibits considerable promise in oil-water separation and thermal insulation.

Enhancing the high-voltage performances of Ni-rich cathode materials by homogeneous La2O3 coating via a freeze-drying assisted method

Ting Ren,Jufeng Zhang,Ding Wang,Peng Dong,Jianguo Duan,Xue Li,Shuai Rao,Dianhua Huang,Yingjie Zhang

The major limitations of layered LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials are their severe capacity decay and marked impedance increase under a high cutoff voltage. Herein, a LiNi 0.5 Co 0.2 Mn 0.3 O 2 powder was successfully encapsulated by a compact and continuous La 2 O 3 thin layer via a facile freeze-drying method. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy , and X-ray photoelectron spectroscopy. The excellent thermal stability and favorable lithium ion conductivity of the La 2 O 3 -modified sample lead to a substantial improvement in its electrochemical performances. In particular, the coated sample exhibits a capacity retention of 80% at 1 C over 150 cycles, while that of the bare electrode is only 58% at a high cutoff voltage of 4.6 V. The alternating current impedance and cyclic voltammetry tests reveal that the La 2 O 3 coating can reduce the cell polarization and enhance the electrochemical activity of cathode materials .

Refined microstructure and enhanced mechanical properties in Mo-Y2O3 alloys prepared by freeze-drying method and subsequent low temperature sintering

Weiqiang Hu,Tao Sun,Chenxi Liu,Liming Yu,Tansir Ahamad,Zongqing Ma

The ultrafine Mo-Y 2 O 3 composite powders were successfully synthesized by innovative freeze-drying method. Consequently, the freeze-dried Mo-Y 2 O 3 composite powders with high sintering activities possess an average grain size of 54 nm. After low temperature sintering at 1600 °C, the Mo-Y 2 O 3 alloys maintaining a high density (99.6 %) have the finest grain size (620 nm) comparing with available literature about oxide dispersion strengthened molybdenum alloy (ODS-Mo). The oxide particles remain their small size (mainly <50 nm) within Mo grains and at Mo grain boundaries. Furthermore, the Y 5 Mo 2 O 12 particles were firstly observed within Mo matrix, and its formation can absorb nearby oxygen impurities, which involves the purification of Mo matrix. The mechanical properties show that Mo-Y 2 O 3 alloy possess a high hardness of 487 ± 28 HV 0.2 , a high yield strength of 902 MPa, a high compressive strength of 1110 MPa, respectively. Our work suggests that freeze-drying and subsequent low temperature sintering can shed light on the preparation of ultrafine ODS-Mo alloys with high performance.

Synthesis and application study of α-Al2O3 with large specific surface area at high-temperature by hydrothermal-assisted freeze-drying

Siyi Li,Pinyi Wang,Jianyun Hu,Guangcan Yang,Youjun Lu,Zhenxia Yuan,Xiao Zhang,Sen Liang

γ-AlOOH nanopowder synthesized using hydrothermal-assisted freeze-drying was employed as a precursor, with AlF₃ as a sintering aid, to explore the preparation of α-Al₂O₃ with a high specific surface area at elevated temperatures. The γ-AlOOH nanopowder produced in this study exhibited superior dispersion, achieving a specific surface area of 198.06 m 2 /g and a zeta potential of 45.8 mV. At a calcination temperature of 1200 °C, the resulting α-Al₂O₃, synthesized from γ-AlOOH and AlF₃, maintained a specific surface area of 27.72 m 2 /g, significantly higher than the typical values reported in the literature (generally below 10 m 2 /g). The α-phase purity exceeded 99 %, and the [AlO₆] proportion was 95.07 %. Furthermore, at a calcination temperature of 1150 °C, the specific surface area of the α-Al₂O₃ reached 50.48 m 2 /g. Using this α-Al₂O₃ as a carrier, a composite TiO₂ catalyst was prepared via a sol-gel and hydrothermal method. This catalyst demonstrated a photocatalytic degradation rate of over 98 % for rhodamine B (10 mg/L) within 30 min of irradiation, under the illumination of a 300 W mercury lamp in proximity to the light source.

Mechanical performance and thermal stability of glass fiber reinforced silica aerogel composites based on co-precursor method by freeze drying

Ting Zhou,Xudong Cheng,Yuelei Pan,Congcong Li,Lunlun Gong,Heping Zhang

In order to maintain the integrity, glass fiber (GF) reinforced silica aerogel composites were synthesized using methltrimethoxysilane (MTMS) and water glass co-precursor by freeze drying method. The composites were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, uniaxial compressive test, three-point bending test, thermal conductivity analysis, contact angle test, TG-DSC analysis. It was found that the molar ratio of MTMS/water glass could significantly affect the properties of composites. The bulk density and thermal conductivity first decreased and then increased with the increasing molar ratio. The composites showed remarkable mechanical strength and flexibility compared with pure silica aerogel. Moreover, when the molar ratio is 1.8, the composites showed high specific surface area (870.9 m 2 /g), high contact angle (150°), great thermal stability (560 °C) and low thermal conductivity (0.0248 W/m·K). These outstanding properties indicate that GF/aerogels have broad prospects in the field of thermal insulation.

Comparative Evaluation of Spray-Drying Versus Freeze-Drying Techniques on the Encapsulation Efficiency and Biofunctional Performance of Chenpi Extract Microcapsules

Jiawei Zhao,Xueling Qin,Ying Liu,Qingyun He,Junwei Qin,Fei Shen,Zhenqiang Wu

Chenpi extracts (CPEs) are highly valued for their rich bioactive compounds and distinctive aromatic properties, but their environmental sensitivity poses stability challenges in food applications. In this study, CPE microcapsules were fabricated using corn peptide as the wall material, and the functional properties of spray-dried microcapsules (SDMCs) and freeze-dried microcapsules (FDMCs) were systematically characterized and compared. The results demonstrate that SDMCs exhibit superior characteristics compared to FDMCs, including reduced moisture content, lower hygroscopicity, enhanced solubility, smaller particle size, and a more uniform microstructure. Both FDMCs and SDMCs showed excellent thermal stability. The SDMCs of CPE encapsulated 93.45% of flavonoids, 90.35% of polyphenols, and 81.32% of sugars from the CPE, while also demonstrating exceptional retention of key terpene volatile compounds, particularly D-limonene (44.63%), γ-terpinene (45.18%), and β-myrcene (40.17%). In contrast, FDMCs exhibited stronger retention of alcohol-based volatile compounds. Furthermore, SDMCs displayed higher antioxidant and hypoglycemic activities, along with improved storage stability. In vitro digestion results reveal that SDMCs provide enhanced protection for CPE flavonoids and polyphenols, achieving bioaccessibility rates of 95.64% and 94.57%, respectively. These findings offer a theoretical basis for optimizing the drying processes in CPE microencapsulation, striking a balance between functional properties and flavor preservation for advanced food applications.

Vacuum freeze drying combined with catalytic infrared drying to improve the aroma quality of chives: Potential mechanisms of their formation

Jingyi Han,Jiakang Liang,Yao Li,Hafida Wahia,Otu Phyllis,Cunshan Zhou,Lei Zhang,Li Chen,Xuguang Qiao,Haile Ma

This study aimed to investigate the effect of vacuum freeze drying combined with catalytic infrared drying (FD-CIRD) process on aromas, free amino acids, reducing sugars and free fatty acids in chive leaves and stems. Gas chromatography-mass spectrometry combined with multivariate data analysis revealed that dipropyl disulfide was the key aroma that distinguished the differences between chive leaves and stems. The key aromas benzeneacetaldehyde, decanal and 1-octen-3-ol enhanced FD-CIRD chive leaves and stems aromas. The free amino acid content was highest at FD-CIRD stage in all samples except for the control (FD), while the reducing sugar content was lowest. The content of unsaturated fatty acids gradually decreased at FD stage and increased at FD-CIRD stage. Additionally, correlation analysis revealed that phenylalanine was a potential precursor of benzacetenealdehyde, oleic and linolenic acids were potential precursors of decanal and 1-octen-3-ol. Therefore, FD-CIRD technique helps to improve the sensory profile of dried chives.

Low thermal-conductivity and high thermal stable silica aerogel based on MTMS/Water-glass co-precursor prepared by freeze drying

Yuelei Pan,Song He,Lunlun Gong,Xudong Cheng,Congcong Li,Zhi Li,Zhong Liu,Heping Zhang

In this paper, hybrid silica aerogels were prepared by methltrimethoxysilane (MTMS) and water-glass co-precursor through two-step sol-gel process followed by freeze drying (FD). The characteristics of aerogels were strongly affected by the molar ratio of MTMS/Water-glass. When the molar ratio is 5.1, hybrid aerogel was obtained with good performances, such as low density (0.083   g/cm 3 ), high contact angle (155.1°) and low thermal conductivity (0.0226   W/m·K). The density, contact angle and thermal conductivity of aerogels based on co-precursor are still showing excellent thermal stability with the same performances after 550   °C heat-treatment.

WITHDRAWN: Porous Si3N4 ceramics with uniform microstructure fabricated by in-situ pre-gel casting combined with non-directional freeze-drying

Heng Zhang,Dongxu Yao,Ming Zhu,Yongfeng Xia,Jun Zhao,Yu-Ping Zeng

Freeze-drying and hot-pressing strategy to embed two-dimensional Ti0.87O2 monolayers in commercial polypropylene films with enhanced dielectric properties

Tian Wenchao,Yan Fei,Cai Cailing,Wu Zeyi,Zhang Chenchen,Yin Ting,Lao Sijia,Hu Linfeng

The dielectric capacitor has been widely used in advanced electronic and electrical power systems due to its capability of ultrafast charging-discharging and ultrahigh power density. Nevertheless, its energy density is still limited by the low dielectric constant(≈ 2.2) of the commercial dielectric polypropylene (PP). The conventional enhancement strategy by embedding inorganic fillers in PP matrix is still difficult and challenging due to that PP hardly dissolves in any inorganic/organic solvent. In this work, we develop a new strategy including freeze-drying, surface functionalization, and hot-pressing to incorporate Ti 0.87 O 2 monolayers in PP film. A series of uniform composited Ti 0.87 O 2 @PP film has been successfully fabricated with Ti 0.87 O 2 content range of 0–15 wt%. The maximum dielectric constant of the as-prepared Ti 0.87 O 2 @PP film is 3.27 when the Ti 0.87 O 2 content is 9 wt%, which is about 1.5 times higher than that of pure PP. Our study provides a feasible strategy to embed two-dimensional material into commercial PP thin-film with superior dielectric performance for practical application.

Freeze drying under vacuum assisted synthesis of LiFePO4@MWCNTs composite with phytic acid as phosphorus source for advanced Li-storage

Yin Li,Li Wang,Hui Zhang,Feng Liang,Yaochun Yao,Keyu Zhang

Three-dimensional (3D) LiFePO 4 @MWCNTs composite has been prepared using phytic acid as the phosphorus source by a simple solvothermal method combined with freeze drying under vacuum. The relationships between the phase structures, the morphologies and electrochemical performance characteristics of the as-prepared samples are studied using a series of characterization methods. It is found that the MWCNTs wrap around the LiFePO 4 particles to form a 3D network because of the reactions between the special functional groups of the phytic acid with Fe 2+ and –C O or –COOH on the surface of the functionalized MWCNTs, resulting in the improvement of conductivity and the electron and ion transport. Due to these merits of MWCNTs and phytic acid, the LiFePO 4 @MWCNTs exhibits good electrochemical performance with high initial discharge capacities of 152.7, 149.6 and 138.8 mAh g −1 at 1, 2 and 5C, respectively. Even at 10C, it still delivers a capacity of 117.5 mAh g −1 .

Unravelling the migration of bioactive and volatile compounds coupled with water sublimation from grapes to recovered water during dynamic freeze-drying

Mengru Li,Wei Zhang,Yuan Huang,Xiaoying Zhang,Wuernisha Kadeer,Leihong Mao,Yuqian Jiang,Rong Tsao,Yao Tang

The production of raisins by freeze-drying (FD) generates large volumes of water removed from fresh grapes, which contains antioxidant-active substances and volatile aromatic compounds. The migration pattern of those compounds and their interaction with water during dynamic FD was investigated, and results revealed that the free and weakly bound water in grape tissues gradually reduced as internal pores formed. Through high-performance liquid chromatography characterization, the concentration of total phenolic compounds in the recovered water peaked around 3 mg/L at 60 h, alongside the identification of key volatile compounds such as linalool and ethyl butyrate. The migration of these compounds was closely linked to the moisture decrease in the grapes, suggesting that the water sublimation facilitated the transfer of beneficial compounds to the recovered water. This study provides theoretical foundation for utilizing recovered water as value-added resource in food industry.