JOURNAL OF POLYMER RESEARCH
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2020
·Vol. 27
·期 6
·1-9
·
IF 2.426
Zhao Xuanchen,Bi Yuanjing,Song Shixin,Liu Chuang,Lv Xue,Sun Shulin
The researches on how to prepare the polymer composites with high dielectric constant (high-k) and low dielectric loss were important for the rapid development of electronic industry. In this paper, by using silane coupling agent, the multi-wall carbon nanotubes (MWCNTs) could graft the thiol groups with high chain transfer constant on the surface, which made the polystyrene (PS) chain coat more efficiently on the surface of MWCNTs to form the core-shell structure. 1 H NMR, TGA and TEM results, showed polystyrene were grafted on the surface of MWCNTs. The grafted PS could reduce the dielectric loss of composite materials and promote the dispersion of the coating MWCNTs in the matrix. In addition, the insulating layer effectively improved the interaction between the MWCNTs and PS matrix, which strengthened the binding force between the filler and matrix, resulting in the increase of the thermal stability of the PS composites. In terms of AC conductivity, the insulating layer could effectively prevent the contact between adjacent MWCNTs from forming a complete conducting network, which inhibited the generation of leakage current. Therefore, compared with untreated multi-wall carbon nanotubes/polystyrene composites, the above composites had excellent dielectric properties with high dielectric constant (214) and low dielectric loss (2.23) at low CNTs mass fraction (4 wt%).
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POLYMER BULLETIN
·
2020
·Vol. 78
·期 5
·2483-2503
·
IF 2.014
Mao Hui,Wang Weiji,Ma Yongle,Huang Yan
An anionic polymer P (ANAN) of acrylamide, N -vinyl-2-pyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid was synthesized through free radical polymerization and initiated by 2,2′-Azobis (2-methylpropionamide) dihydrochloride as an anti-high temperature and anti-calcium and magnesium contamination fluid loss control additive for water-based drilling fluid. The P (ANAN) was characterized by 13 C-NMR and 1 H-NMR, FTIR, elemental analysis and GPC analysis. The fluid loss tests were carried on different WBDFs. The results showed that this polymer can resist 4.5 × 10 5 ppm of Cl −1 , 4 × 10 5 ppm of Ca 2+ contamination at low pH environment caused by acid gas invasion in drilling fluid at 180 °C. The fluid loss control mechanisms of P (ANAN) were investigated by Zeta potential analysis, particle size distribution analysis and mud cake quality analysis. The thermal stability was investigated by TGA analysis. The results illustrate that the P (ANAN) exhibits a stronger interaction with clays and higher-temperature resistance, and it can improve the colloidal dispersion property obviously for drilling fluid under salts, calcium and magnesium contamination and even under circumstances of acid gas invasion conditions. Due to its superior fluid loss control properties, the P (ANAN) can be a promising polymer for water-based drilling fluid in deep and ultra-deep well drilling applications.
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CHEMICAL PAPERS
·
2020
·Vol. 74
·期 11
·4125-4133
·
IF 1.68
Wang Faqiang,Chen Lei,Xu Dong,Li Zhanxiong
Tetrafluoro-λ 6 -sulfanyl (–SF 4 –) was synthesized via oxidative fluorination and used as a bridging group to bond perfluoroalkyl to phenylene. As a result, perfluoroalkylphenyltrichlorosilane was prepared by hydrosilylation using perfluoroalkylstyrene as a raw material under platinum catalytic conditions. And the corresponding monolayers produced a coating on silicon surfaces by spontaneous self-assembly from solution. Due to the introduction of –SF 4 –, it can increase the shielding effect of the fluoroalkyl group and reduce the surface energy of the material on the basis of extending the length of the perfluoroalkyl chain. At the same time, the sulfur–carbon bond formed by the bridge group is more likely to decrease under ultraviolet light. Once the bridge bond is broken, the perfluoroalkyl-terminated carbon chain perfluoroalkyl group is decomposed and detached. Therefore, the fluorine-containing material has good ultraviolet light degradation property, and the obtained fluorine-containing material is environmentally friendly. The self-assembled film containing a perfluoroalkylsilane can effectively reduce the friction properties and adhesion of the substrate, and the substrate modified with the self-assembled film containing a perfluoroalkylsilane has good stability.
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Food and Bioprocess Technology
·
2020
·Vol. 13
·期 7
·1119-1130
·
IF 3.356
Zhou Xin,Tan Zhuo,Zhou Qian,Shi Fei,Yao Miaomiao,Wei Baodong,Cheng Shunchang,Ji Shujuan
Cold storage can effectively delay the ripening of ‘Nanguo’ pears ( Pyrus ussuriensis Maxim.). However, the aroma-related esters of ‘Nanguo’ pears decreased after cold storage. In this study, we aimed to investigate the effect of intermittent warming (IW) treatment on the formation of aroma-related esters and unsaturated fatty acid synthesis from cold stored pears. IW-treated pears were exposed to 20 ± 1 °C for 1 day every 20 days during storage at 0 ± 0.5 °C, every 21 days was a cycle and a total of 90 days. The pears in control group were stored at 0 ± 0.5 °C for 90 days. After this 90-day storage, both groups of pears (control and IW-treated) were transferred to a shelf life of 12 days at room temperature. The results showed that, compared with the pears in control group, the productions of aroma-related esters and the expression levels of PuLOX1 , PuADH3 , and PuAAT1 in IW-treated pears were significantly higher during the shelf life ( P < 0.05). At the same time, IW-treated pears maintained significantly higher contents of linoleic acid and linolenic acid ( P < 0.05), which were precursors of aroma compounds. We also found that the expression of PuFAD2 and PuFAD3 had significant positive correlation with the contents of unsaturated fatty acids ( P < 0.05). The significantly higher expression levels of PuFAD2 and PuFAD3 in IW-treated pears may have played an important role in the improvement of ester contents ( P < 0.05). It could be inferred that IW treatment had an impact on the aroma-related esters of cold-stored ‘Nanguo’ pears through regulation of unsaturated fatty acid synthesis.
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RARE METALS
·
2020
·Vol. 40
·期 2
·374-382
·
IF 2.161
He Si-Ru,Zou Jian-Peng,Chen Li-Bao,Chen Yue-Jiao
Abstract In this work, nickel/T-Nb 2 O 5 nanoparticles encapsulated in mesoporous carbon nanofibers (denoted as Ni/T-Nb 2 O 5 @CNFs) are successfully prepared through a simple electrospinning route and succedent heating treatment. The presence of Ni in carbon nanofibers is beneficial for enhancing the electronic conductivity and the initial Coulombic efficiency. Ni/T-Nb 2 O 5 nanoparticles are homogeneously incorporated in carbon nanofibers to form a nanocomposite system, which provides effective buffering during the lithiation/delithiation process for cycling stability. The Ni/T-Nb 2 O 5 @CNFs show high surface area (26.321 m 2 ·g −1 ) and mesoporous microstructure, resulting in higher capacity and excellent rate performance. The Ni/T-Nb 2 O 5 @CNFs exhibit a remarkable capacity of 437 mAh·g −1 at a current density of 0.5 A·g −1 after 230 cycles and a capacity of 173 mAh·g −1 at a current density up to 10.0 A·g −1 after 1400 cycles. This work indicates that nickel/T-Nb 2 O 5 nanoparticles encapsulated in carbon nanofibers can be a promising candidate for anode material in high-power LIBs. Graphic abstract
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CELLULOSE
·
2020
·Vol. 27
·期 12
·7023-7036
·
IF 4.21
Zhou Man,Chen Jingwen,Jiang Mengting,Zhang Yakang,Liang Qian,Xu Song,Yao Chao,Li Zhongyu
A series of thickness-controlled SrTiO 3 (commonly abbreviated ST) anchored on carbonized bacterial cellulose (CBC) was successfully prepared by a novel route of freeze-drying assisted crystallization/carbonization. For the first time, the cross-linked bacterial cellulose served as a carbon source as well as structure-directing scaffold for the construction of ST/CBC composites. Characterizations exhibited cracks and defects on the surface of CBC which provided ideal anchoring sites for the dispersion and crystallization of ST. Additionally, the relationship between morphology and photocatalytic activity of ST/CBC was carefully investigated by photocatalytic reduction of potassium dichromate (K 2 Cr 2 O 7 ) and degradation of tetracycline in water. This unique biomass-derived carbon fibers provide an ideal platform for further design of perovskite based materials with enhanced catalytic performance.
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Stem Cell Research & Therapy
·
2020
·Vol. 11
·期 1
·1-11
·
IF 5.116
Liao Naishun,Shi Yingjun,Wang Yingchao,Liao Fangyu,Zhao Bixing,Zheng Youshi,Zeng Yongyi,Liu Xiaolong,Liu Jingfeng
Background Although it has been preclinically suggested that adipose tissue-derived mesenchymal stem cell (ADSC)-based therapy could effectively treat chronic liver diseases, the hepatic engraftment of ADSCs is still extremely low, which severely limits their long-term efficacy for chronic liver diseases. This study was designed to investigate the impact of antioxidant preconditioning on hepatic engraftment efficiency and therapeutic outcomes of ADSC transplantation in liver fibrotic mice.Methods Liver fibrosis model was established by using intraperitoneal injection of carbon tetrachloride (CCl4) in the male C57BL/6 mice. Subsequently, the ADSCs with or without antioxidant pretreatment (including melatonin and reduced glutathione (GSH)) were administrated into fibrotic mice via tail vein injection. Afterwards, the ADSC transplantation efficiency was analyzed by ex vivo imaging, and the liver functions were assessed by biochemical analysis and histopathological examination, respectively. Additionally, a typical hydrogen peroxide (H2O2)-induced cell injury model was applied to mimic the cell oxidative injury to further investigate the protective effects of antioxidant preconditioning on cell migration, proliferation, and apoptosis of ADSCs.Results Our data showed that antioxidant preconditioning could enhance the therapeutic effects of ADSCs on liver function recovery by reducing the level of AST, ALT, and TBIL, as well as the content of hepatic hydroxyproline and fibrotic area in liver tissues. Particularly, we also found that antioxidant preconditioning could enhance hepatic engraftment efficiency of ADSCs in liver fibrosis model through inhibiting oxidative injury.Conclusion sAntioxidant preconditioning could effectively improve therapeutic effects of ADSC transplantation for liver fibrosis through enhancing intrahepatic engraftment efficiency by reducing oxidative injuries. These findings might provide a practical strategy for enhancing ADSC transplantation and therapeutic efficiency.
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JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 55
·期 27
·13363-13371
·
IF 3.553
Cao Yutao,Yuan Yue,Shang Yafen,Zverev Vladimir I.,Gimaev Radel R.,Barua R.,Hadimani R. L.,Mei Lan,Guo Gang,Fu Hao
Micro-sized particles of Fe x Rh 100− x ( x = 50, 48, 45, 40, and 35) binary alloys were synthesized by a solid-phase reduction method and their structural properties, magnetic properties and cytotoxicity have been characterized. From X-ray diffraction results, the Fe 50 Rh 50 alloy is in a single chemically ordered α ′ phase while the face-centered cubic disordered γ phase arises and increases with Rh content when x is smaller than 50. The magnetization behavior of the alloys demonstrates that the α ′ phase consists of ferromagnetic and antiferromagnetic components due to the nonuniformity of elements in the particulate alloys. The maximal magnetic entropy change and the relative refrigeration capacity of the Fe 50 Rh 50 particles reach 9.7 J/kg K and 230 J/kg, respectively, with a 0–3 T magnetic field change. Despite its moderate magnetic entropy among the first-order transition materials, Fe 50 Rh 50 microparticles are promising for biomedical applications due to its large relative cooling power and low cytotoxicity.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2020
·Vol. 126
·期 7
·1-7
·
IF 1.81
Li Peipei,Peng Xinsheng
Au–Cu bimetallic nanomaterials have attracted tremendous attention in the field of catalysis, water splitting, biosensor and biotherapy. Au 3 Cu nanocrystals with a definite stoichiometric ratio and ordered arrangement of atoms have shown great potential for efficient catalyts. Herein, we reported a new method for fabrication of Au 3 Cu nanocrystals. Their morphologies can be tuned by the amount of hydrochloric aqueous solution, including nanosquare and frame were achieved, respectively. The as-synthesized Au 3 Cu nanosquares not only demonstrated a comparatively high sensitivity of 324.8 μA mM −1 cm −2 as a non-enzymatic glucose sensor but also performed well in CO catalytic oxidation even at 50 °C with a conversion efficiency of 30 mmol g −1 h −1 .
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POLYMER BULLETIN
·
2020
·Vol. 78
·期 6
·2993-3008
·
IF 2.014
Chen Yuying,Chen Juan,Li Jianping,Jiang Jingzhe,Fang Ziang,Lin Xing,Jiang Yan,Zhang Hongwen,Liu Hongbo
In this study, a macroinitiator of β-CD-ONa was prepared by a substitution reaction of β-cyclodextrin (β-CD) with sodium (Na). The macroinitiator was then used in the ring-opening polymerization of octamethylcyclotetrasiloxane (D 4 ) to obtain a star polymer, in which β-CD is the core and polysiloxane is the arm. FTIR, NMR, TGA, CA, etc., were used to characterize the structure and properties of star polymers. The results indicated that there were four polysiloxane arms attached to each β-CD core, and the star polymer had good thermal stability. With the increase in D 4 monomer dosage, the hydrophobicity of the star polymer slightly improved, but the reaction time had no significant effect on hydrophobicity. When the star polymer was coated onto polyethylene terephthalate membrane, the transmittance increased from 87.6% to 92.8%, and the haze did not change significantly. Furthermore, the surface of star polymer porous membranes was prepared by the static breath-figure method using n -hexane as solvent at 30 °C. The results showed uniform pore distribution and increased hydrophobicity.
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Journal of Oceanology and Limnology
·
2020
·Vol. 38
·期 5
·1517-1531
·
IF 0.617
Tian Jing,Chen Zhuoyuan,Jing Jiangping,Feng Chang,Sun Mengmeng,Li Weibing
The Cu 2 O/TiO 2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition. Field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array, but also on the wall of TiO 2 nanotubes. The Cu 2 O deposition amount could be adjusted by changing the deposition time. The photoelectrochemical cathodic protection (PECCP) performance of the prepared photoelectrodes for 316L stainless steel (SS) was tested under visible light. The constant current deposition time had a significant effect on the PECCP performance of Cu 2 O/TiO 2 -X photoelectrodes and Cu 2 O/TiO 2 -20 had the best PECCP performance for the coupled 316L SS. This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2 , in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.
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Nature Communications
·
2020
·Vol. 11
·期 1
·1-8
·
IF 12.121
Feng Jiaqi,Gao Hongshuai,Zheng Lirong,Chen Zhipeng,Zeng Shaojuan,Jiang Chongyang,Dong Haifeng,Liu Licheng,Zhang Suojiang,Zhang Xiangping
Developing effective catalysts based on earth abundant elements is critical for CO 2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO ( j CO ) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N 3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a j CO of 14.0 mA cm −2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher j CO of 29.7 mA cm −2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N 3 site, which facilitates the formation of the key intermediate COOH * through a lowered free energy barrier.
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