ENERGY
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2021
·
IF 7.147
Hongyang Li,Chengzhi Hu,Yichuan He,Dawei Tang,Kuiming Wang,Xianfeng Hu
To further enhance the melting rate of the metal foam composite phase change material (MFCPCM), we took partial and gradient optimizations on the pore densities of metal foams. The partially optimized models, including Partial-80-5-5 and Partial-5-5-80, were compared with the Uniform-5 model. Results show that the Partial-80-5-5 model has the most developed melting among the three models. It illustrates that enlarging the pore density in the top region is conducive to accelerating the whole melting process. Besides, through a further comparison of the Partial-80-5-5, Partial-40-5-5, and Partial-20-5-5 models, we concluded that the larger the pore-density in the top region is, the faster the melting is. Subsequently, the gradient optimizations, including Gradient-80-20-5 and Gradient-80-40-5 models, were experimented with and analyzed. It was obtained that the Gradient-80-40-5 model has the fastest melting rate among all models. The inhibition of the large pore density on natural convection at the top and middle regions causes a strong vortex at the bottom region, so the melting process is significantly reinforced. Through the optimizations on the metal foam's pore density, the energy storage rate can achieve a prominent enhancement.
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APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Ruixiang DENG,Bingbing CHEN,Haogeng LI,Zhong LI,Tao ZHANG,Yun YU,Lixin SONG
Microwave shielding materials and absorbers serve important roles in improving the reliability of smart devices and military equipment. In this work, three-dimensional (3D) Ti 3 C 2 T x /Fe 3 O 4 composites with adjustable electromagnetic responses are studied. Taking advantage of the negatively charged surface of the Ti 3 C 2 T x , the cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to precipitate the delaminated Ti 3 C 2 T x sheets. The volatilization of CTAB during the annealing process inflates the Ti 3 C 2 T x , and leads to the three-dimensional architecture of the composite. The results show that the free-standing 3D Ti 3 C 2 T x /Fe 3 O 4 composite film exhibits a high shielding efficiency of 60 dB in the X band. Owing to the traits of great flexibility, low apparent density, and thin thickness, the 3D Ti 3 C 2 T x /Fe 3 O 4 composite film achieves a high specific shielding efficiency of 3.5 × 10 5 dB/(g·cm −2 ). Furthermore, through the control of crystal defects in one-step annealing treatment, the shielding material can be transformed into a wideband microwave absorber. A high reflection loss up to −57 dB can be realized. And a 2-mm-thick absorber whose reflection loss is better than −10 dB in 11.2 ~ 18 GHz is also achieved. The experimental and first-principal studies on the evolution mechanism reveal that the destruction of the Ti-C bond mainly leads to the degradation of electrical conductivity and the improvement of impedance matching. Introduced crystal defects can help enhance the dielectric loss as well. The synergistic effects of ohmic loss, dielectric loss, and magnetic loss give birth to a broadband absorption of the composite.
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LANGMUIR
·
2021
·
IF 3.882
Pan Huang,Han Jia,Tingyi Wang,Yingbiao Xu,Lingyu Zhang,Xin Wei,Haidong Jia,Shijie Wen,Kaihe Lv,Dexin Liu
Colloidal stability of modified graphene oxide (GO) is fundamental for its practical applications. Meanwhile, most of the investigations mainly focused on the nanosheets modified by a certain amount of modifiers and neglected the effects of the modification degree, which could vary the physical and chemical properties of modified GO and significantly affect its stability in solution. To the best of our knowledge, this study initially investigated the impact of modification degrees on the colloidal stability of graphene-based amphiphilic Janus nanosheets (JGO) via both experimental and theoretical approaches. The prepared JGO, asymmetrically grafted by dodecylamine, exhibited a direct relation between the modification degree and nanosheet thickness, refractive index, electrostatic properties, hydrophobicity, and the ultimate colloidal stability. In addition, the ionic strength imposed distinctive influences on the aggregation behavior of JGO. Based on the comparison between experimental results and theoretical calculation, it was revealed that the JGO should be modeled as two-dimensional (2D) nanosheets in pure water and be treated as 3D spherical particles in electrolyte solutions for the prediction with the extended Derjaguin–Landau–Verwey–Overbeek theory.
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高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2021
·
IF 2.993
Jiaqi Zu,Zhengjun Yao,Ruiyang Tan,Liqiang Jin,Li Wan,Jinsen Hou,Ping Chen,Jintang Zhou
The formation of core–shell structure is one of the standard methods to improve the corrosion resistance of carbonyl iron powders (CIPs). In this manuscript, epoxy resin (EP) was coated on the surface of flaky carbonyl iron particles (FCIPs) by a simple one-step polymerization method to form the FCIP@EP composite particles, and they were used to obtained microwave response to accurately simulate, predict and optimize the microwave absorption performance of composites. After being coated by epoxy resin, the composite exhibits a higher percolation threshold; the absorbing performance is more stable in an acidic environment. The optimal loading of FCIP@EP in the matrix can be obtained by data-driven optimization, and the model calculation results are in good agreement with the actual measured ones. At 23 vol%, the composite's effective absorption bandwidth (EAB, RL < −10 dB) can reach a maximum of 7.63 GHz at 1.5 mm thickness, and the EAB covers all X-band and all Ku-band at 1.9 mm and 1.4 mm, respectively. The whole optimization process provides a guiding basis for the modified corrosion-resistant absorbers in design applications.
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FOOD AND CHEMICAL TOXICOLOGY
·
2019
·
IF 3.775
Jiankang Wang,Yutong He,Deqing Yu,Liang Jin,Xiaobao Gong,Baoshun Zhang
Perilla oil (PerO), a natural oil with a high unsaturated fatty acid content derived from the mature seeds of Perilla frutescens , is a homology of medicine and food . The type 2 diabetes mellitus (T2DM) model was successfully established using a high-fat and high-sugar diet combined with a single low-dose of streptozocin (STZ). PerO intervention reduced the levels of fasting blood glucose and the level, size and accumulation of lipid droplets , increased the insulin level and diminished the body weight loss. PerO pretreatment markedly promoted the serum levels of alanine transaminase (ALT) and aspartate transaminase alanine (AST) and inhibited the levels of glucose (GLU), glucose-6-phosphate dehydrogenase (G6PD), triglycerides (TGs) and total cholesterol (TC). Moreover, PerO treatment enhanced the expression of phosphoinositide-3 kinase (PI3K)/protein kinase B (AKT) and activated the expression of glucose transporter 4 (Glut4) and phospho-AKT serine/threonine kinase (p-AS160) in the liver. Additionally, PerO treatment distinctly decreased the abundance of Aerococcus and facilitated the richness of Alloprevotella in the intestine, as well as accelerated the restoration of the gut microflora diversity. Thus, PerO regulates intestinal microbiota and alleviates insulin resistance through the PI3K/AKT signaling pathway in type-2 diabetic KKAy mice and may be a potential functional food for diabetic treatment.
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JOURNAL OF BIOMATERIALS APPLICATIONS
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2019
·
IF 2.442
Anmin Zhou,Zhaoyang Ye,Yan Zhou,Wen-song Tan
Microparticles with porous structure can be applied as microcarriers for both cell culture and tissue regeneration. While well-controlled pore structure represents a critical challenge to be achieved. In the present study, in order to develop microcarriers for cell culture, a series of poly(ε-caprolactone) microspheres were fabricated with varied macroporous structures. Poly(ε-caprolactone) microspheres were prepared via the integration of the emulsion/solvent evaporation and particle leaching mechanisms. Particularly, by adjusting poly(ε-caprolactone) concentration and the ratio between the porogen paraffin and poly(ε-caprolactone), the microspheres with the pore size of 25.6–84.0 μm and the porosity of 57.4–75.5% were obtained. Further, the microspheres were subjected to alkaline hydrolysis, followed by surface coating with hydroxyapatite. These porous poly(ε-caprolactone) microspheres with surface modification well supported the adhesion and growth of human fibroblasts. Together, bioactive poly(ε-caprolactone) microspheres with controlled pore structure are potential to be applied in cell culture and tissue regeneration.
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ACS Omega
·
2019
·
IF 2.584
Chao Chang,Peng Tao,Benwei Fu,Jiale Xu,Chengyi Song,Jianbo Wu,Wen Shang,Tao Deng
Solar steam generation is critical for many important solar-thermal applications, but is challenging to achieve under low solar flux due to the large evaporation enthalpy of water. Here, we demonstrate a three-dimensional porous solar-driven interfacial evaporator that can generate 100 °C steam under 1 sun illumination with a record high solar-to-steam conversion efficiency of 48%. The high steam generation efficiency is achieved by localizing solar-thermal heating at the evaporation surface and controlling the water supply onto the porous evaporator through tuning its surface wettability, which prevents overheating of the evaporator and thus minimizes conductive, convective, and radiative heat losses from the evaporator. The design of steam outlet located at the sidewall of the evaporator rather than from the solar absorber surface not only facilitates the collection of generated steam, but also avoids potential blockage of solar radiation by the condensing steam. The high-efficiency solar-driven evaporator has been used to generate hot steam for outdoor removal of paraffin on the wall of oil pipelines, offering a promising solution to mitigate the wax deposition issue in petroleum extraction processes.
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ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Dafan Chen,Yiming Li,Mutai Bao,Yajie Hou,Jiafeng Jin,Zichao Yin,Zhining Wang
Because of the differences in physicochemical properties, it is of a great challenge to achieve efficient and simultaneous removal of various pollutants from water only based on one material. In this study, magnetic silica microrods (R-Fe3O4@SiO2) were successfully fabricated and used for the removal of coexisting pollutants (oil, heavy metals, soluble organic dyes) in water. R-Fe3O4@SiO2 could act as an effective solid stabilizer to disperse oil contaminants into droplets, due to its high adsorption energy at the oil–water interface. The encapsulated oil by R-Fe3O4@SiO2 could be effectively separated from water by applying a magnetic field. Simultaneously, R-Fe3O4@SiO2 could adsorb soluble cationic dyes and heavy metals through electrostatic interactions. The maximal removal capacity of R-Fe3O4@SiO2 for various pollutants in water was compared with that of some of the previously reported materials, and they showed a satisfied result. Additionally, the removal capacity of R-Fe3O4@SiO2 particles for multiple coexisting contaminants in water was evaluated. It is worthy to note that R-Fe3O4@SiO2 still showed a great removal capacity for multiple coexisting pollutants even after five runs of a sorption–desorption cycle. These results revealed that this technically simple R-Fe3O4@SiO2 material is a feasible material for the removal of various coexisting pollutants in water, and thus it holds great prospects as a candidate for the one-step water purification in practical applications.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 18
·11827-11840
·
IF 3.442
Zuo Yuxin,Yao Zhengjun,Lin Haiyan,Zhou Jintang,Guo Xinlu,Cai Haishuo
Carbonyl iron powder (CIP) coated with a layer of epoxy (EP) shell, denoted as core–shell CIP@EP composites, were designed and prepared via in situ polymerization. The CIP@EP composites containing 4.5–6.8 wt% EP were systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, scanning and transmission electron microscopy, and vector network analyzer. The results indicated that CIP@EP composites with 9–254 nm EP shell thickness were successfully prepared through an efficient in situ polymerization method. The particle diameter of core CIP particles was 0.49–4.24 µm. The microwave absorption properties of the microspheres were then experimentally measured, and the CIP@EP composites exhibited a maximum reflection loss value of − 66.2 dB at 7.1 GHz at 2.0 mm absorber thickness. The effective absorbing bandwidth below − 10 dB was 8.0 GHz (from 10.0 to 18.0 GHz). The presence of the EP shell not only enhanced the microwave absorption performance of CIP@EP composites but also improved the overall chemical stability of CIP particles. The as-prepared CIP@EP composites may be a promising candidate for electromagnetic wave absorption applications, and the core–shell structure design can be extended to other microwave absorption materials.
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ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Haishan Wu,Weiwei Zhang,Junjie Wu,Yuwu Chi
Nowadays, people are facing more and more threats from solar UV radiation due to global ozone layer depletion and the ozone hole. Therefore, it is highly desirable to develop a fast, simple, and sensitive sensor for solar UV radiation. In this work, recently emerging perovskite quantum dots (PQDs) with excellent optical properties are used for sensing solar UV radiation. PQDs with high quantum yields are protected in solid paraffin to obtain paraffin-PQD composite (P-PQD) film. The hydrophobic and compact paraffin not only can protect PQDs from degradation by water and air for long-term use but also is transparent to UV light and thus maintains the high quantum yield of PQDs. The P-PQD film shows high sensing sensitivity for solar UV radiation based on which a novel visual ratiometric luminescence sensing strategy for UV light has been developed. The visual ratiometric luminescence sensor for solar UV radiation adopts a paraffin-encapsulated red fluorescence PQD (P-r-PQD) film as the sensing unit for UV light and a green luminescence light-emitting diode as reference light. When exposed to different solar UV radiation, the sensing film shows wide color variations from green to red, which can easily observed by the naked eye or recorded by a camera. On the basis of this, a simple and visualized solar UV index-reporting system has been established.
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高影响因子
POLYMER SCIENCE SERIES B
·
2019
·Vol. 61
·期 1
·77-85
·
IF 0.907
Yanfei Wang,Mo Gaoming,He Liu,Huang Qing
Abstract Isothermal gelation processes for relatively low concentration PAN/DMSO/H 2 O solutions are studied by rheology. Winter–Chambon criterion is unitedly used to investigate the rheological kinetics and the structural and mechanical characteristics of the resulted gels are evaluated. It is found that during the isothermal gelation procedure, two coincident points appear sequentially, where loss tangent tan δ is independent of frequency. The occurrence of two coincident points suggests that the critical gel forms first, then it evolves into the second self-similar structure, and the average distance between crosslinks of network becomes shorter. The results also show that decreasing temperature, increase of PAN concentration or H 2 O content will lead to faster gelation kinetics and formation of more elastic and compact critical gel and the second self-similar structure. At the same temperature, the later formed second self-similar structure is always more elastic and compact than the critical gel, and the corresponding gel stiffness is stronger.
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RSC Advances
·
2019
·Vol. 9
·期 18
·9962-9967
·
IF 3.049
Yiwen Hu,Xiuduo Song,Qilong Zheng,Jiangning Wang,Jiangfei Pei
Zeolitic imidazolate framework-67 (ZIF-67), a new kind of metal–organic framework, has large surface area as well as outstanding thermal and chemical stability. In this paper, micro-sized ZIF-67 crystals were prepared and further employed as the reinforcing material to design novel paraffin-based composite phase change materials (PCMs) with a polymethyl methacrylate (PMMA) shell. The composite PCMs were fabricated by using a ZIF-67 crystal-stabilized oil-in-water (O/W) Pickering emulsion as a template. Morphologies and thermal properties of the prepared composite PCMs with different contents of ZIF-67 crystals were determined by SEM, DSC and TGA. Results showed that the ZIF-67 concentration in the emulsion system has a significant effect on the microstructure, phase change behavior and thermal stability of the resultant composite PCMs. When adding 1.5 g of ZIF-67 crystals, the resultant composite PCMs achieved a stable sphere-like structure and had about 106.06 J g−1 of latent heat. The prepared composite PCMs also exhibited a good thermal stability. Compared with pure paraffin, the thermostability of the shape-stabilized paraffin was significantly enhanced at a low content of ZIF-67 crystals.
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