MACROMOLECULES
·
2012
·
IF 5.167
Aiguo Sui,Xincui Shi,Shupeng Wu,Hongkun Tian,Yanhou Geng,Fosong Wang
A new catalyst system, i.e., nickel acetylacetonate/1,3-bis(diphenylphosphino)propane (Ni(acac)2/dppp), was explored to catalyze the Kumada catalyst transfer polycondensation (KCTP) of three fluorene monomers with different substituents at 9-position. The “living” nature of the polymerization was confirmed by polymerization kinetic studies, “monomer addition” experiment and block copolymerizations. As a result, poly(9,9-dioctylfluorene)s (PF8s) with the number-average molecular weights (Mns) in the range 2.8–62.2 kDa and polydispersity indices (PDIs) of ∼1.20 were successfully synthesized in a controlled manner. The syntheses of fluorene-fluorene and fluorene-thiophene diblock copolymers with Mns up to 46 kDa were also demonstrated. A complex, i.e. Ni(dppp)(acac)2, with an octahedral coordination geometry was isolated and confirmed by X-ray crystallographic analysis. The polymerization experiments indicated that the in situ formed Ni(dppp)(acac)2 should be the active catalyst. To the best of our knowledge, this is the first report on the controlled synthesis of polyfluorenes (PFs) via KCTP.
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RSC Advances
·
2014
·Vol. 4
·期 45
·23853-23860
·
IF 3.708
Pranav K. Tripathi,Mingxian Liu,Lihua Gan
Synthesis of carbon materials with enhanced surface areas, and regular and tuned pore diameters is always a great challenge. In this report, ordered mesoporous carbons (OMCs) were synthesized by the one-step assembly of tri-constituents, and the OMCs were applied as an adsorbent for the removal of the highly hazardous water pollutant di(2-ethylhexyl)phthalate (DEHP). Phloroglucinol–formaldehyde based carbon precursor was in situ prepared during the assembly of the tri-constituents, and the surface area and mesopore diameter of the OMCs were tuned by variation of the molar ratio of formaldehyde to phloroglucinol. Small angle X-ray diffraction patterns revealed that the obtained carbons are highly ordered, which is in agreement with the measuring results of transmission electron microscopy at low and high resolution. Scanning electron microscopy images demonstrate that OMC-F2.0 has a hierarchical morphology. Nitrogen adsorption–desorption measurements revealed that the surface area of the OMCs (956–1801 m2 g−1) was dependent on the molar ratio of the carbon precursor constituents (formaldehyde to phloroglucinol). By varying the molar ratio of formaldehyde to phloroglucinol from 1.0 to 4.0, the mesopore diameter of the OMCs was shifted to the higher side, from 2.1 to 3.1 nm. DEHP was efficiently removed from a model water pollutant by the OMCs. OMC-F2.0 achieved the highest adsorption capacity of 364 mg g−1 for the removal of DEHP. The adsorption equilibrium data were treated with the two mathematical models of Langmuir and Freundlich, and the results revealed that decontamination was more favorable with the Langmuir model. This concludes that the removal of DEHP by OMCs depends on the surface area, and the DEHP molecules occupied the porous space of the OMCs in a monolayer manner.
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CARBON
·
2022
·
IF 11.307
Zhe Zou,Mingqiang Ning,Zhenkuang Lei,Xueheng Zhuang,Guoguo Tan,Jianhua Hou,Hui Xu,Qikui Man,Jingbo Li,Run-Wei Li
Ti 3 C 2 T x is considered a candidate for high-efficiency microwave absorption materials due to its adjustable electrical conductivity , low density and high specific surface area in recent years. However, the single absorption mechanism could not meet the practical requirements as the functional microwave absorbers. Herein, 0D/1D/2D architectures of Co@C/MXene with 0D Co nanoparticles , 1D carbon nanotubes (CNTs) and 2D Ti 3 C 2 T x MXene nanosheets were rationally fabricated to enhance the microwave attenuation performance, in which Co@CNTs were in situ grown on Ti 3 C 2 T x MXene nanosheets . By changing the amount of Ti 3 C 2 T x MXene to optimize the impedance matching properties, the Co@C/M − 10 absorber exhibits excellent microwave attenuation performance with a minimum reflection loss of −50.5 dB at 5.9 GHz under a thickness of 4.0 mm. Meanwhile, the maximum effective absorption bandwidth (<−10 dB) of Co@C/M − 10 absorber can reach 5.8 GHz under 2.0 mm. The remarkable absorption performance can be ascribed to the synergistic effects of interface polarizations and magnetic loss. Moreover, the radar cross section (RCS) simulation was also performed via CST. Under the incident angle of 0°, the RCS reduction value of Co@C/M − 10 can reach 33.5 dBm 2 . This work provides a strategy for synthesizing MXene-based composite materials with tunable electromagnetic attenuation and wide absorption bandwidth performance .
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Cell Reports
·
2023
·Vol. 42
·期 11
·113349-113349
·
IF 8.8
Shao Q,Wijaya CS,Wang S,Meng X,Yuan C,Ma C,Xu S
Maintaining cellular viability relies on the integrity of the plasma membrane, which must be repaired upon damage. Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion is a crucial mechanism involved in membrane repair. In C. elegans epidermal cell hyp 7, syntaxin-2 (SYX-2) facilitates large membrane wound repair; however, the underlying molecular mechanism remains unclear. Here, we found that SNAP-25 protein RIC-4 and synaptobrevin protein SEC-22 are required for SYX-2 recruitment at the wound site. They interact to form a SNARE complex to promote membrane repair in vivo and fusion in vitro. Moreover, we found that SEC-22 localized in multiple intracellular compartments, including endosomes and the trans-Golgi network, which recruited to the wounds. Furthermore, inhibition of RAB-5 disrupted SEC-22 localization and prevented its interaction with SYX-2. Our findings suggest that RAB-5 facilitates the formation of the RIC-4/SEC-22/SYX-2 SNARE complex and provides valuable insights into the molecular mechanism of how cells repair large membrane wounds.
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PubMed
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 20
·9723-9732
·
IF 8.867
Jiaguang Zheng,Xuezhang Xiao,Liuting Zhang,Shouquan Li,Hongwei Ge,Lixin Chen
A remarkable improvement in the hydrogen desorption performance of Mg(BH4)2–NaBH4 eutectic composite is achieved by simply ball-milling with fluorographene (FG). It is found that the desorption temperature of Mg(BH4)2–NaBH4 (∼200 °C) is still too high and liquid phase appears during dehydrogenation. Particularly, the novel bowl-like 3D Mg(BH4)2–NaBH4–FG composite can be formed after ball-milling. The novel Mg(BH4)2–NaBH4–FG exhibits a low dehydrogenation temperature of 114.9 °C with 6.9 wt% of pure hydrogen in seconds. In-depth investigations show that such greatly improved hydrogen desorption properties of the Mg(BH4)2–NaBH4–FG composite could be ascribed to both the “novel bowl-like 3D structure” with large specific surface area and the “reactant destabilized modification” owing to the decrease of the reaction enthalpy caused by the formation of NaMgF3. This finding provides a facile preparation of complex borohydride composites with low dehydrogenation temperature and fast rate, which accelerates its practical application in fuel cells.
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RSC Advances
·
2015
·Vol. 5
·期 57
·45693-45702
·
IF 3.84
Anming Li,Dekang Xu,Hao Lin,Shenghong Yang,Yuanzhi Shao,Yueli Zhang,Zhenqiang Chen
Well-crystallized and uniform NaGd(MoO4)2 microcrystals with morphologies of bipyramids, truncated bipyramids, quasi-cubes and tetragonal plates were selectively synthesized via a facile hydrothermal method without any additives under mild conditions. The effects of Na2MoO4/Gd(NO3)3 molar ratios and pH values of precursor solutions on the phase and morphology of the as-synthesized microcrystals were systematically investigated. The molar ratios and pH values played key roles in the selective synthesis of pure phase NaGd(MoO4)2 microcrystals with regular morphology. With increasing Na2MoO4/Gd(NO3)3 molar ratios in the appropriate pH range, the morphology of the products changed from bipyramids, truncated bipyramids, quasi-cubes to tetragonal plates, namely, the morphological truncation degree increased gradually. NaGd(MoO4)2 tetragonal microplates could be synthesized at the molar ratio of 9 : 1. A possible morphological formation mechanism of NaGd(MoO4)2 tetragonal microplates was proposed, i.e. nucleation-Ostwald ripening growth process. Color tunable photoluminescence properties of NaGd(MoO4)2:Eu3+,Tb3+ microcrystals were studied in detail. Among the different morphologies of NaGd(MoO4)2:5% Eu3+ microcrystals, tetragonal microplates had a broadened, red-shifted and enhanced charge transfer band in the excitation spectrum. What's more, the full-width at half-maximum for the charge transfer band of the tetragonal plates was highest (58 nm), which favored efficient excitation and absorption in the ultraviolet region. The introduction of a small amount of Tb3+ into NaGd(MoO4)2 microplates doped with Eu3+ would enhance the 5D0 → 7FJ transition of Eu3+ at 616 nm due to the energy transfer process of cross-relaxation from Tb3+ to Eu3+. Multicolor tunable luminescence from deep red, red, orange, yellow to green under 291 nm ultraviolet excitation and from red, reddish orange to pink under 380 nm near-ultraviolet excitation could be obtained in NaGd(MoO4)2 tetragonal microplates by simply adjusting the doping concentrations of Eu3+ and Tb3+, suggesting NaGd(MoO4)2:Eu3+,Tb3+ microcrystals might have practical application in optoelectronic devices, such as light emitting diodes and color display systems. This facile morphology-controlled hydrothermal synthesis strategy was simple, low-cost and environment-friendly, and might be extended to other inorganic materials.
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Membranes
·
2022
·Vol. 12
·期 8
·728
·
IF 4.562
Yifan Li,Jing Hu,Joan Papavasiliou,Zhiyong Fu,Li Chen,Haibin Li
This work exhibits an effective approach to enhance the performance of membrane-electrode assembly (MEA) with KH5(PO4)2-doped PBI membrane, by adding phosphoric acid (PA) in the catalyst layer (CL). The ohmic resistance and single-cell performance of the MEA, treated with PA, are reduced by ~80% and improved by ~800%, respectively, compared to that of untreated MEA. Based on the MEA pretreated with PA, the influence of humidity and temperature on the resistance and the single-cell performance are investigated. Under humidified gas conditions, the ohmic resistance of MEA is reduced but the charge transfer resistance is slightly increased. Regarding the effect of temperature, the ohmic resistance of MEA becomes lower as the temperature elevates from 140 to 180 °C, but increases at 200 °C. The maximum peak power density presents at 180 °C and 20% RH with 454 mW cm−2. The peak power density is favored with temperature increase from 140 to 180 °C, but decreases with further increase to 200 °C. Moreover, when dry gas conditions are employed, the output performance is unstable, suggesting that humidification is necessary to inhibit degradation for a long-term stability test.
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Inorganic Chemistry Frontiers
·
2022
·Vol. 9
·期 21
·5645-5652
·
IF 7.779
Yuan Lin,Chun-Li Hu,Zhi Fang,Jin Chen,Wei-Jie Xie,Yan Chen,Jian-Pu Wang,Jiang-Gao Mao
Three new potassium rare earth carbonates, namely KRE(CO3)2 (RE = Eu, Gd, Tb), were synthesized successfully. Their structures feature a novel [RE(CO3)2]− 3D framework with 1D channels along the c axis filled with K+ cations. Among them, KEu(CO3)2 and KTb(CO3)2 emit strong red and green photoluminescence, respectively. The birefringence values of KRE(CO3)2 were measured as 0.149, 0.162 and 0.215 at 546 nm, respectively. Remarkably, KTb(CO3)2 has the largest experimental birefringence among carbonates reported.
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JOURNAL OF CHEMICAL PHYSICS
·
2022
·Vol. 156
·期 1
·
IF 4.304
Lei Xueyan,Fu Zhengping,Xiang Bin,Lu Yalin
The low stability and poor activities of transition metal selenides (TMSs) in alkaline electrolyte limit their application in supercapacitors. Metal doping and hybridization of various electroactive materials with different properties are utilized to enhance the electrochemical performance of TMSs by optimizing their electronic structure and providing rich electrochemical active sites. Herein, we report a simple two-step hydrothermal method for the growth of Zn-doped NiSe 2 and Ni(OH) 2 nanocomposites on Ni foam [Zn–NiSe 2 /Ni(OH) 2 ]. The resulting material delivers high specific capacity (1525.8 C g −1 /564.7 mA h g −1 at 6 A g −1 and 1220 C g −1 at 10 A g −1 ) in a three-electrode system. A Zn–NiSe 2 /Ni(OH) 2 //porous carbon (PC) aqueous asymmetric supercapacitor (ASC) was built by utilizing Zn–NiSe 2 /Ni(OH) 2 as the positive electrode and PC as the negative electrode. This Zn–NiSe 2 /Ni(OH) 2 //PC ASC shows an energy density of 75.8 W h kg −1 at a power density of 916.1 W kg −1 and achieves a specific capacity retention of 100% after 25 000 cycles at 10 A g −1 . These results reveal that the Zn doping and the hybridization of NiSe 2 with Ni(OH) 2 can obtain impressive electrochemical properties in ASCs.
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NANOTECHNOLOGY
·
2018
·Vol. 29
·期 6
·065501
·
IF 3.404
Xiang Ran,Zhenzhen Wang,Enguo Ju,Fang Pu,Yanqiu Song,Jinsong Ren,Xiaogang Qu
The logic device demultiplexer can convey a single input signal into one of multiple output channels. The choice of the output channel is controlled by a selector. Several molecules and biomolecules have been used to mimic the function of a demultiplexer. However, the practical application of logic devices still remains a big challenge. Herein, we design and construct an intelligent 1:2 demultiplexer as a theranostic device based on azobenzene (azo)-modified and DNA/Ag cluster-gated nanovehicles. The configuration of azo and the conformation of the DNA ensemble can be regulated by light irradiation and pH, respectively. The demultiplexer which uses light as the input and acid as the selector can emit red fluorescence or a release drug under different conditions. Depending on different cells, the intelligent logic device can select the mode of cellular imaging in healthy cells or tumor therapy in tumor cells. The study incorporates the logic gate with the theranostic device, paving the way for tangible applications of logic gates in the future.
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INTERNATIONAL DAIRY JOURNAL
·
2022
·
IF 3.572
Yaqi Tu,Lei Guan,Fazheng Ren,Hao Zhang
This study sought to research the antigenicity and functional characteristics of Maillard reaction products (MRPs) arising from the human breast milk oligosaccharide , 2′-fucosyllactose (2′-FL), and β-lactoglobulin (β-LG). The MRPs were prepared at 60 °C, 96 h and 79% relative humidity. During the Maillard reaction, the content of ultraviolet-absorbing and fluorescence compounds, and browning products increased. The free amino groups content decreased by 61.5% during the first 48 h then did not change significantly. The results of sodium dodecylsulphate polyacrylamide gel electrophoresis showed that high molecular mass MRPs were generated and the intrinsic fluorescence spectra suggested a masking effect of 2′-FL. The surface hydrophobicity of β-LG-2′-FL increased and the antigenicity of the MRPs reduced significantly compared with the control β-LG, with the inhibition rate reaching 49.09%. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and ferric reducing/antioxidant power assay revealed significant increases in the antioxidant activity of the MRPs.
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JOURNAL OF ORGANIC CHEMISTRY
·
2024
·
IF 3.3
Nan Wang,Yuanyuan Huang,You Zi,Mengke Wang,Weichun Huang
A practical and regioselective direct N-alkylation of 2-pyridones is enabled by use of α-keto esters in the P(NMe2)3-mediated deoxygenation process. The reaction proceeds under mild conditions to produce N-alkylated 2-pyridones with high selectivity and generality, and the protocol is shown to be applicable for the scale-up synthesis, which makes it promising for practical applications.
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